Re: L6-20P - L6-30R
On 03/19/2014 06:33 PM, Rob Seastrom wrote: It's not the conductor that you're derating; it's the breaker. Per NEC Table 310.16, ampacity of #12 copper THHN/THWN2 (which is almost certainly what you're pulling) with 3 conductors in a conduit is 30 amps. Refer to Table 310.15(B)(2)(a) for derating of more than 3 current-carrying conductors in a conduit. 4-6 is 80%, 7-9 is 70%. Plenty good for 20 amps for any conceivable number of conductors in a datacenter whip. Thermal breakers are typically deployed in an 80% application for continuous loads, per NEC 384-16(c). See the references to 125% of continuous load, which of course is the reciprocal of 80%. Actually, there is no NEC 384.16 any more, at least in the 2011 code. The current relevent, perhaps even replacement, article seems to be the exception listed to article 210.20(A). Now, 210.21(B)(2) indicates that, for each individual receptacle on a multi-receptacle, the total cord and plug connected load cannot be above certain values (which are 80% of the branch circuit rating for 15, 20, and 30A circuits) regardless of overcurrent protection device rating. If you have a 100% rated overcurrent device you could connect a total load on multiple receptacles beyond 80%, it appears. While 210.21(B)(1) requires receptacles on single-receptacle branch circuits to be rated for the full load, any one piece of utilization equipment on a 20A or 30A branch circuit cannot be rated to draw more than 80% of the branch circuit's rating (210.23(A)(1) for 20A, 210.23(B) for 30A). So even if you have a single receptacle on the branch circuit you can't have any single piece of equipment use 100% continuously. The idea is to give the branch circuit some 'headroom;' in the ideal world, we don't load networking links past a certain percentage, depending on link technology, for similar reasons. Tracking code changes fuels an entire industry, and several websites. :-) Not to mention continuing education and license renewals for electricians. and headaches for those who think they understand the code but then get a surprise at inspection time (been there, done that, go the t-shirt and the NEC Handbook so I'll halfway know what I'm talking about when dealing with these things.) A new NEC Handbook is in my budget every three years due to the substantial changes that are made by the committees. The physics of electricity don't change, but our understanding of those physics and our ideas about how to deal safely with electricity do. And what is allowable and available can change in a moment; I'm still a bit puzzled how the L6-30P to L6-20R adapters can actually be on the market in the first place, given that they can easily create an unsafe condition. Well, I'm puzzled from a technical viewpoint, but not from a marketing viewpoint.if it makes money, it is marketable, until pulled or recalled.
Re: L6-20P - L6-30R
Lamar Owen lo...@pari.edu writes: Actually, there is no NEC 384.16 any more, at least in the 2011 code. Guilty. I reflexively reached for my 2008 copy since that's the code of record here where I live. Glad we're not on 2011, wish we were still on 2005; a lot of stupidity has crept in since then. Tamper-resistant receptacles required in the unfinished basement shop? *really*? -r
Re: L6-20P - L6-30R
On Thu, Mar 20, 2014 at 4:00 PM, Rob Seastrom r...@seastrom.com wrote: Lamar Owen lo...@pari.edu writes: Actually, there is no NEC 384.16 any more, at least in the 2011 code. Guilty. I reflexively reached for my 2008 copy since that's the code of record here where I live. Glad we're not on 2011, wish we were still on 2005; a lot of stupidity has crept in since then. Tamper-resistant receptacles required in the unfinished basement shop? *really*? Think of the children! I hear the 2017 edition of NFPA 70 (aka NEC) may require one to turn off the power to the entire household in order to plug in a coffee maker to minimize potential arc flash hazard (just kidding). Gary
Re: L6-20P - L6-30R
Is it too late to demand code be in open Github repos with changes tracked at no cost? On Thu, Mar 20, 2014 at 12:12 PM, Gary Buhrmaster gary.buhrmas...@gmail.com wrote: On Thu, Mar 20, 2014 at 3:05 PM, Lamar Owen lo...@pari.edu wrote: . Tracking code changes fuels an entire industry, and several websites. :-) The redline PDF at least makes it (more easily) possible to notice the changes for your evening reading pleasure.
Re: L6-20P - L6-30R
On 03/20/2014 12:27 PM, Gary Buhrmaster wrote: Think of the children! I hear the 2017 edition of NFPA 70 (aka NEC) may require one to turn off the power to the entire household in order to plug in a coffee maker to minimize potential arc flash hazard (just kidding). Gary ROTFL. No, I'll just don my $700 arc-flash suit (8 cal per sq cm rated) before making coffee in the morning. While I say that somewhat tongue-in-check, arc flash really is serious business, see the youtube video called 'Donnie's Accident' to see how serious; I had to have a suit because I am in charge of the power monitoring for our data centers, and hooking up our Fluke 435 on the input to our Mitsubish 9900B UPS requires full arc flash protection at the 8 cal level. I'm glad it's not on our main switchgear, though, as the 6,000A busses there require 40 cal suits, and those are really expensive. The smaller feeders don't require the full suit, but I have made a habit of wearing it any time I make a measurement with the 435, even on the small 30KVA PDU's, mainly just to make it a habit, since one wrong move can be very painful. All to get our actual PUE to do the adjustments on our receptacle costs for our data centers. (our PUE, depending upon the time of year, runs between 1.1 and 1.4, by the way). But that's drifting even farther off-topic.
Re: L6-20P - L6-30R
On 3/18/14 3:54 PM, George Herbert wrote: This sort of thing is usually an adapter, a little cylinder with a L6-20R on one end and a L6-30P on the other, since the loads are safe. Either that, or a short jumper cable wired the same way. The loads aren't safe. You will have a 30-amp circuit breaker feeding the L6-30R socket. The load and its wiring are only rated for 20 amps so if there's an overload you will exceed the ampacity of the wiring downstream of the L6-20P and the L6-20P itself. Option 1: Change the breaker to 20A and change the receptacle to L6-20R. Option 2: Buy a 30-amp rated PDU equipped with L6-30P plug. -- Jay Hennigan - CCIE #7880 - Network Engineering - j...@impulse.net Impulse Internet Service - http://www.impulse.net/ Your local telephone and internet company - 805 884-6323 - WB6RDV
Re: L6-20P - L6-30R
On Mar 20, 2014, at 4:52 PM, Jay Hennigan j...@west.net wrote: On 3/18/14 3:54 PM, George Herbert wrote: This sort of thing is usually an adapter, a little cylinder with a L6-20R on one end and a L6-30P on the other, since the loads are safe. Either that, or a short jumper cable wired the same way. The loads aren't safe. You will have a 30-amp circuit breaker feeding the L6-30R socket. The load and its wiring are only rated for 20 amps so if there's an overload you will exceed the ampacity of the wiring downstream of the L6-20P and the L6-20P itself. Option 1: Change the breaker to 20A and change the receptacle to L6-20R. Option 2: Buy a 30-amp rated PDU equipped with L6-30P plug. Option 3: Put a 20A breaker or fuses inline in the Adapter. Owen
Re: L6-20P - L6-30R
Alex Rubenstein a...@corp.nac.net writes: Go look at any standard household lamp. It has a 5-15P on the end of it, which could be plugged into an outlet rated for 20 amps (5-20R), with 16 gauge lamp cord rated for 10 amps or less. Mine all seem to be NEMA 1-15P, some (most?) with 18 AWG wire. Have I been shortchanged? :) -r
RE: L6-20P - L6-30R
Go look at any standard household lamp. It has a 5-15P on the end of it, which could be plugged into an outlet rated for 20 amps (5-20R), with 16 gauge lamp cord rated for 10 amps or less. Mine all seem to be NEMA 1-15P, some (most?) with 18 AWG wire. Have I been shortchanged? :) I wrote that too fast, you are absolutely right. But my point remains. Appliance/load wire size is often, and many times smaller than the ampacity of the circuit. Heck, how many times have you plugged in a 14 gauge extension cord to a 5-20R?
Re: L6-20P - L6-30R
On 03/18/2014 09:39 PM, William Herrin wrote: Meh. It depends. Plug that 30 amp power strip into a 20 amp circuit. Try to use more than 20 amps and the main breaker trips. No problem. Plug that 20 amp power strip into a 30 amp circuit. Try to use more than 20 amps and the strip's breaker trips. No problem. Get a short before the strip breaker and the main breaker trips before the wires can heat. There just aren't a whole lot of failure modes here that result in fire short of one or the other breaker failing. And that results in fire regardless of the amperage mismatch. The amount of misinformation in this thread is astonishing. This, by the way, is why you're allowed to plug that 22 gauge Christmas light wire into a 15 amp receptacle even though it can't handle 15 amps: the 3 amp fuse will blow if there's a short. Just don't plug in anything with lower-rated wire that doesn't have its own breaker or fuse. Regards, Bill Herrin Note that in those cases the fuse is in the plug; anywhere else wouldn't be ok. As small as 18AWG may be used for fixture wire on a 20A circuit, per 240.5(B)(2)(1). 2011 NEC article 210.23(A) permits 15A receptacles on 20A branch circuits; 30A branch circuits must use 30A receptacles. If the OP's 30A branch circuit has an L6-20R on it then this would be a violation; see NEC Table 210.24 for a summary of the code. 406.8 is the article requiring that cord caps (plugs) are not supposed to be interchangeable. Now, article 240.5 is the relevant article in the NEC. This can get a bit tricky to apply; if the PDU in question is *listed* for connection to a 30A circuit then that's OK (240.5(B)(1)); the individual fixture wires within the PDU for a 30A PDU can be as small as 14AWG as long as they're protected (240.5(B)(2)(4)), but field assembled extension cord sets for a 30A circuit would need 10AWG conductors, as they aren't covered by the exception in 240.5(B)(4) and thus fall under 240.5(A). It's definitely allowed to connect a 30A PDU with 10AWG conductors to a 30A branch circuit; anything else could be OK, depending upon the local authority having jurisdiction and its interpretation of the 240.5 exceptions, which aren't the clearest section of the NEC, IMO. And article 645, dealing with ITE rooms, only requires that cords be listed for use with IT equipment and be less than 4.5m in length. IMO, and my degree is in EE, it is possible to have a fault condition in a 12AWG cord that won't trip a 30A breaker but could cause a fire and be prior to the input breaker in the PDU. The OP appears to be doing the right thing and getting a 30A PDU.
Re: L6-20P - L6-30R
Alex Rubenstein a...@corp.nac.net writes: But my point remains. Appliance/load wire size is often, and many times smaller than the ampacity of the circuit. Heck, how many times have you plugged in a 14 gauge extension cord to a 5-20R? I do this all the time. In (all our) defense, lamp cord is the closest thing to conductors in free air that most people will ever run into, and although the insulation isn't high temperature stuff, the heat buildup isn't the same as a few dozen THHN conductors in EMT. If you want something that will make your head explode a little (until you think it through and realize that ampacity is just another way of expressing i^2r losses plus dissipation rate), read NEC table 630.11(A), and then 630.12(A) and noodle on just how skinny a wire you can use for hooking up a (home, low duty cycle) welder that's breakered at 50 amps. 12 AWG anyone? -r
Re: L6-20P - L6-30R
On Tue, Mar 18, 2014 at 07:09:49PM -0400, David Hubbard wrote: I've had to do that before; provider gave me a 208v/30a circuit and I already had a power strip I wanted to re-use that had a corded L6-20P connector on it. I purchased a L6-30P plug / L6-20R receptacle adapter from http://www.stayonline.com/nema-locking-6-30-amp-adapters.aspx They're only $25 and they ship overnight if needed. They have one foot cabled versions of the same thing too if you have tight working space and there's not enough room for both connectors back to back; works as a strain relief too so maybe that option is better regardless. This is not really a safe thing to do unless the adapter has a 20A circuit breaker as part of it, or if you change out the upstream circuit breaker from 30A to 20A (and hopefully clearly mark the outlet as such). If you're trying to go the other direction, plugging an L6-30P into an L6-20R 20 amp circuit, that I'd recommend against because it never fails that someone says hey, 30 amp power strip, let me plug some more stuff into it not realizing it's on a 20 amp breakered circuit, then all your stuff goes down while you try to find the facility staff to reset the breaker. Going this way is safe, but as you say, you can only draw 20A (actually, you can usually only draw a derated 80% of that, so 16A).
Re: L6-20P - L6-30R
On Wed, Mar 19, 2014 at 9:07 AM, Lamar Owen lo...@pari.edu wrote: 2011 NEC article 210.23(A) permits 15A receptacles on 20A branch circuits; 30A branch circuits must use 30A receptacles. If the OP's 30A branch circuit has an L6-20R on it then this would be a violation; see NEC Table 210.24 for a summary of the code. Hi Lamar, Nobody is talking about putting an L6-20R on a 30 amp circuit. OP was talking about putting an L6-30P on a 20 amp appliance: a PDU that has its own 20 amp breaker. Big difference. Regards, Bill Herrin -- William D. Herrin her...@dirtside.com b...@herrin.us 3005 Crane Dr. .. Web: http://bill.herrin.us/ Falls Church, VA 22042-3004
Re: L6-20P - L6-30R
On 03/19/2014 09:51 AM, William Herrin wrote: Nobody is talking about putting an L6-20R on a 30 amp circuit. OP was talking about putting an L6-30P on a 20 amp appliance: a PDU that has its own 20 amp breaker. Big difference. If the PDU isn't listed for 30A then it's the essentially the same thing, safety-wise. Unless there is overcurrent protection at the source of the feed to the conductors of the flexible cord (240.21) that meets the ampacity of the conductors of said flexible cord, unless one of the exceptions of 240.5 apply, then it's a potentially unsafe condition (NEC doesn't directly apply to supply cords of appliances themselves; that's what the 'listing' is for from UL or similar; see http://ecmweb.com/code-basics/nec-rules-overcurrent-protection-equipment-and-conductors for more info, and see UL's FAQ entry for modifications to listed equipment at www.ul.com/global/eng/pages/offerings/perspectives/regulator/faq/). Just replacing an L6-20P with an L6-30P on a 20A-listed PDU would be unsafe and (IMO) unwise, since the breaker in the input of the PDU does not protect the flexible cord's conductors from internal overcurrent faults. A 20A listed PDU should have 20A overcurrent protection to the connected receptacle, in addition to any overcurrent protection internal to the PDU. A cord with a 20A ampacity may overheat significantly if it faults internally in such a way as to cause more than 20A, but less than 30A (or whatever overcurrent protection is in the branch circuit), to flow; there are numerous ways cords can fault in this manner. You could easily get a situation where the cord is partially faulted internally but the PDU's breaker doesn't detect it because the fault shunts current ahead of that breaker; again, not a dead short but still an overcurrent fault. I've seen this type of fault before, where the cord itself was shunting a few amps prior to the PDU input breaker (in this particular case the cord was damaged by lightning, even though the equipment to which it was connected still had power). But the other condition, where a 20A breaker is feeding a 30A PDU, could result in dropping power to the PDU but is not unsafe. I know that I wouldn't approve (in the NEC-speak sense of that word) of the use of any of these adapters or similar kludges in my data centers, as the insurance liability issues are potentially much more costly than just buying the right PDU or running a branch circuit with the correct overcurrent protection in the first place. It also depends a bit on exactly how the PDU is listed. You can look up the listing's details in the UL White Book (download link: http://www.ul.com/global/documents/offerings/perspectives/regulators/2013_WB_LINKED_FINAL.pdf ). But the final say rests with the authority having jurisdiction, AHJ in NEC-speak.
Re: L6-20P - L6-30R
On Wed, Mar 19, 2014 at 11:22 AM, Lamar Owen lo...@pari.edu wrote: Just replacing an L6-20P with an L6-30P on a 20A-listed PDU would be unsafe and (IMO) unwise, since the breaker in the input of the PDU does not protect the flexible cord's conductors from internal overcurrent faults. Yet an 18 awg PC power cable is perfectly safe when plugged in to a 5-20R on a circuit with a 20 amp breaker. Get real man. You got two things right: The NEC (and related fire codes) don't apply to supply cords of appliances in circumstances such as OP's PDU. The modification cancels the UL certification. If you have an external requirement to use only UL certified components then you can't make any modifications no matter how obviously safe they are. By the way, you either don't have that requirement or you're breaking it. Your custom network cables are not UL certified. Regards, Bill Herrin -- William D. Herrin her...@dirtside.com b...@herrin.us 3005 Crane Dr. .. Web: http://bill.herrin.us/ Falls Church, VA 22042-3004
Re: L6-20P - L6-30R
On Wed, Mar 19, 2014 at 12:24:38PM -0400, William Herrin wrote: On Wed, Mar 19, 2014 at 11:22 AM, Lamar Owen lo...@pari.edu wrote: Just replacing an L6-20P with an L6-30P on a 20A-listed PDU would be unsafe and (IMO) unwise, since the breaker in the input of the PDU does not protect the flexible cord's conductors from internal overcurrent faults. Yet an 18 awg PC power cable is perfectly safe when plugged in to a 5-20R on a circuit with a 20 amp breaker. Get real man. Not really, that is just a compromise in safety standards for convenience. It was deemed to be safe enough given the comparatively low current 20A circuit and the open-to-air power cord. For higher current circuits 30A and up, the safety standards are more stringent. The NEC (and related fire codes) don't apply to supply cords of appliances in circumstances such as OP's PDU. The modification cancels the UL certification. If you have an external requirement to use only UL certified components then you can't make any modifications no matter how obviously safe they are. By the way, you either don't have that requirement or you're breaking it. Your custom network cables are not UL certified. There is more to safety than just being certified. Acting in ways that /actually/ improves safety (if you are allowed to) is important. This isn't just black and white. Safety, like security, isn't absolute. Both benefit from defense-in-depth, and both require compromise to balance safety vs. convenience.
RE: L6-20P - L6-30R
I recently bought a UPS with a 30R plug on it, and sat and tried for about 20 minutes to plug it into what I thought was a 30 socket. It was, in fact, a 20. They're similar enough that if you're looking at the ends you might be convinced that someone has bent a one of the ends of the plug funny, but no amount of trying will make them fit. Malcolm -Original Message- From: Jay Ashworth [mailto:j...@baylink.com] Sent: Tuesday, March 18, 2014 4:12 PM To: NANOG Subject: Re: L6-20P - L6-30R - Original Message - From: Randy a...@djlab.com I have a situation where a 208v/20A PDU (L6-20P) is supposedly hooked to a 208v/30A circuit (L6-30R). Before I order the correct PDU's and whip cords...sanity check...are connectors 'similar' enough that this is possible (with force) or am I going to find we've actually got L6-20R's on the provider side? As it happens, the chart at http://www.stayonline.com/reference-nema-locking.aspx suggests that the L6-20 and L6-30 are less different than you'd expect. I *think* those are on different diameters, and a datacenter employee ought to friggin' know better... but I don't think it's 100% impossible that this has happened. If it did, you're gonna replace the plug anyway... As long as there's a 20A breaker on the PDU, you're safe, if not within code. Cheers, -- jra -- Jay R. Ashworth Baylink j...@baylink.com Designer The Things I Think RFC 2100 Ashworth Associates http://www.bcp38.info 2000 Land Rover DII St Petersburg FL USA BCP38: Ask For It By Name! +1 727 647 1274
Re: L6-20P - L6-30R
Original Message - From: William Herrin b...@herrin.us On Wed, Mar 19, 2014 at 11:22 AM, Lamar Owen lo...@pari.edu wrote: Just replacing an L6-20P with an L6-30P on a 20A-listed PDU would be unsafe and (IMO) unwise, since the breaker in the input of the PDU does not protect the flexible cord's conductors from internal overcurrent faults. Yet an 18 awg PC power cable is perfectly safe when plugged in to a 5-20R on a circuit with a 20 amp breaker. Get real man. A PC isn't a power distribution device. You got two things right: The NEC (and related fire codes) don't apply to supply cords of appliances in circumstances such as OP's PDU. A PDU is *not* an appliance. The modification cancels the UL certification. If you have an external requirement to use only UL certified components then you can't make any modifications no matter how obviously safe they are. UL doesn't certify items. It lists them. It does so *specifically on behalf of* fire insurors. By the way, you either don't have that requirement or you're breaking it. Your custom network cables are not UL certified. Network cables don't carry power. Generally, Bill, you're one of the Smart People here. But what Lamar says accords with my (limited) formal electrical training, and what you say does not. Cheers, -- jra -- Jay R. Ashworth Baylink j...@baylink.com Designer The Things I Think RFC 2100 Ashworth Associates http://www.bcp38.info 2000 Land Rover DII St Petersburg FL USA BCP38: Ask For It By Name! +1 727 647 1274
Re: L6-20P - L6-30R
You probably should ask your facility operator or electrician what the requirements are (who, unlike most network engineers, is qualified to decide what to do), but it sounds like replacing the PDU is simple and easy, and unquestionably not a bad thing to do. Alternatively, you can replace the 30A circuit with a 20A one. I'm not an electrician, but I'll bet it's not much more complex or expensive than replacing a breaker and a receptacle, and I'd be shocked if it took more than an hour of a qualified person's time, and I suspect it would cost about the same for parts as building some sort of adaptor cord (and less if you the electrician has spare parts - he gets a 30A breaker and 30A socket in exchange for a 20A breaker and 20A socket). The added benefit of 20A, assuming your equipment power usage is low enough to use 20A, is that it's usually cheaper (sometimes significantly) if you're paying someone else for the power circuit each month.
Re: L6-20P - L6-30R
On Wed, Mar 19, 2014 at 1:06 PM, Chuck Anderson c...@wpi.edu wrote: Yet an 18 awg PC power cable is perfectly safe when plugged in to a 5-20R on a circuit with a 20 amp breaker. Get real man. Not really, that is just a compromise in safety standards for convenience. It was deemed to be safe enough Safe. Enough. There is more to safety than just being certified. Acting in ways that /actually/ improves safety (if you are allowed to) is important. This isn't just black and white. Safety, like security, isn't absolute. Both benefit from defense-in-depth, and both require compromise to balance safety vs. convenience. Good advice. Regards, Bill Herrin -- William D. Herrin her...@dirtside.com b...@herrin.us 3005 Crane Dr. .. Web: http://bill.herrin.us/ Falls Church, VA 22042-3004
Re: L6-20P - L6-30R
- Original Message - From: Joel Maslak jmas...@antelope.net Alternatively, you can replace the 30A circuit with a 20A one. I'm not an electrician, but I'll bet it's not much more complex or expensive than replacing a breaker and a receptacle, It is exactly that: no one says you *can't* wire a 20A branch circuit with #10. It is even *possible*, though unlikely, that if you did so, you wouldn't have to derate it to 80%. I would have to reread the Code to be sure. Cheers, -- jra -- Jay R. Ashworth Baylink j...@baylink.com Designer The Things I Think RFC 2100 Ashworth Associates http://www.bcp38.info 2000 Land Rover DII St Petersburg FL USA BCP38: Ask For It By Name! +1 727 647 1274
Re: L6-20P - L6-30R
On Wed, Mar 19, 2014 at 1:18 PM, Jay Ashworth j...@baylink.com wrote: From: William Herrin b...@herrin.us Yet an 18 awg PC power cable is perfectly safe when plugged in to a 5-20R on a circuit with a 20 amp breaker. Get real man. A PC isn't a power distribution device. There are no power cords coming from the power supply that the PC power cable plugs in to? The modification cancels the UL certification. If you have an external requirement to use only UL certified components then you can't make any modifications no matter how obviously safe they are. UL doesn't certify items. It lists them. http://www.ul.com/global/eng/pages/solutions/services/certification/ By the way, you either don't have that requirement or you're breaking it. Your custom network cables are not UL certified. Network cables don't carry power. The 802.3af voip phone on my desk must be powered by magic. Regards, Bill Herrin -- William D. Herrin her...@dirtside.com b...@herrin.us 3005 Crane Dr. .. Web: http://bill.herrin.us/ Falls Church, VA 22042-3004
RE: L6-20P - L6-30R
Just because you say the debate should be ended doesn't mean it's true, or that you are even correct. To end the debate, my staff master electrician says just replace the breaker. Your staff electrician missed half the answer, which would be to replace the breaker AND the receptacle. But you make sound as if the OP has that option readily available to him, and it's doesn't answer is original question. You can leave the outlet if you want or replace it too. Really, a mismatched outlet on a breaker size not intended for it? That seems like a good idea. Doesn't matter. The 30A circuit should be 10 gauge which is fine for 20amp. That part is correct. And to Jay: Network cables most certainly do carry power. No, they carry signal, which is considerably different - unless of course it is 802.1af.
Re: L6-20P - L6-30R
To end the debate, my staff master electrician says just replace the breaker. You can leave the outlet if you want or replace it too. Doesn't matter. The 30A circuit should be 10 gauge which is fine for 20amp. And to Jay: Network cables most certainly do carry power. On 3/19/2014 12:18 PM, Jay Ashworth wrote: Network cables don't carry power.
Re: L6-20P - L6-30R
Fair point. PoE is 48V and current limited, though, precisely to keep it what the Code calls Low Voltage. On March 19, 2014 1:26:54 PM EDT, William Herrin b...@herrin.us wrote: On Wed, Mar 19, 2014 at 1:18 PM, Jay Ashworth j...@baylink.com wrote: From: William Herrin b...@herrin.us Yet an 18 awg PC power cable is perfectly safe when plugged in to a 5-20R on a circuit with a 20 amp breaker. Get real man. A PC isn't a power distribution device. There are no power cords coming from the power supply that the PC power cable plugs in to? The modification cancels the UL certification. If you have an external requirement to use only UL certified components then you can't make any modifications no matter how obviously safe they are. UL doesn't certify items. It lists them. http://www.ul.com/global/eng/pages/solutions/services/certification/ By the way, you either don't have that requirement or you're breaking it. Your custom network cables are not UL certified. Network cables don't carry power. The 802.3af voip phone on my desk must be powered by magic. Regards, Bill Herrin -- William D. Herrin her...@dirtside.com b...@herrin.us 3005 Crane Dr. .. Web: http://bill.herrin.us/ Falls Church, VA 22042-3004 -- Sent from my Android phone with K-9 Mail. Please excuse my brevity.
Re: L6-20P - L6-30R
On Wed, Mar 19, 2014 at 1:55 PM, Jay Ashworth j...@baylink.com wrote: PoE is 48V and current limited, though, precisely to keep it what the Code calls Low Voltage. Hi Jay, 50 watts DC. It won't electrocute you (that's AC) but it's the same power that makes a 40 watt bulb burning hot. Regards, Bill Herrin -- William D. Herrin her...@dirtside.com b...@herrin.us 3005 Crane Dr. .. Web: http://bill.herrin.us/ Falls Church, VA 22042-3004
Re: L6-20P - L6-30R
[Whee. This discussion is good for me, as I need to refresh my memory on the relevant code sections for some new data center clients.thanks, Bill, you're a great help!] On 03/19/2014 12:24 PM, William Herrin wrote: Yet an 18 awg PC power cable is perfectly safe when plugged in to a 5-20R on a circuit with a 20 amp breaker. Get real man. The NFPA thinks so. They also allow interoperability between a 20A T-slot receptacle and a 15A plug (so that a 2-15P can work in a T-slot 2-20R, or a 5-15P can work in a 5-20R, etc). Things are different above 20A, at least in the NFPA's view. NFPA 75 is interesting reading, especially in those sections where its committee and the NFPA 70 committee seem to see things differently. However, my SOP is to use no smaller than 16AWG for a 5-15P or 6-15P (with a 14AWG preference), and no smaller than 12AWG for 20A use, etc, unless protected by suitable overcurrent devices (for 18AWG, that's 7A, and for 16AWG that's 10A, so a power strip with a 10A breaker or a PDU with a individual 10A breakers is fine for use with 16AWG power cords). I do have an EE background and degree, and so I do tend to be very conservative in those things. I have seen the results of pinched 18AWG zipcord in a 5-15R, and it's not pretty. The 22AWG Christmas lights get away with it by having overcurrent protection in the plugs. You got two things right: The NEC (and related fire codes) don't apply to supply cords of appliances in circumstances such as OP's PDU. The modification cancels the UL certification. If you have an external requirement to use only UL certified components then you can't make any modifications no matter how obviously safe they are.By the way, you either don't have that requirement or you're breaking it. Your custom network cables are not UL certified. Here's the bottom line, at least in my data centers: if it could be considered questionable by the insurers (that's where UL got its start) then it's not likely to happen. Modifying a piece of utilization equipment with a UL QPQY listing is likely to be considered questionable. Now, network cable installation is covered by the NEC in article 800, which got some revisions in 2011, and the class 2 and class 3 cables used are also covered, in articles 725 (fiber is covered by article 770, and ITE rooms by article 645). The major theme there is reduction in spread of products of combustion, and the UL DUZX listing reflects that purpose. Yes, listed cables are required by code when part of the premises wiring, but putting a listed connector on listed cable is within the listing. Further, 802.3af and even 802.3at are considered Class 2 power limited sources under article 725 of the NEC (that is, there's not enough available power to initiate combustion). So, sure, I can still use custom network cabling and stay within using only listed items.
Re: L6-20P - L6-30R
On Wed, Mar 19, 2014 at 02:05:42PM -0400, William Herrin wrote: On Wed, Mar 19, 2014 at 1:55 PM, Jay Ashworth j...@baylink.com wrote: PoE is 48V and current limited, though, precisely to keep it what the Code calls Low Voltage. Hi Jay, 50 watts DC. It won't electrocute you (that's AC) but it's the same power that makes a 40 watt bulb burning hot. I don't know where you are getting your facts, but 802.3af maxes out at 15.4W and 802.3at at 34.2W, and DC can electrocute you just as well as AC. http://en.wikipedia.org/wiki/Power_over_Ethernet#Standard_implementation
Re: L6-20P - L6-30R
On 03/19/2014 02:05 PM, William Herrin wrote: 50 watts DC. It won't electrocute you (that's AC) but it's the same power that makes a 40 watt bulb burning hot. 802.3af is limited to 15.4W, and 802.3at to 25.5W. The limits for Class 2 and 3 circuits are found in Chapter 9, Table 11 (A and B), of the NEC (Table 11(B) for DC circuits, and for a power source of 30 to 60 volts a Class 2 circuit can have, for a 44VDC supply power, up to 3.4A available (a max nameplate rating of 100VA). For AC, Table 11(A) tells me that a 120VAC circuit, to meet Class 2, must be current-limited to 5mA. BICSI has a good set of slides on the NEC at http://www.bicsi.org/uploadedfiles/Conference_Websites/Winter_Conference/2012/presentations/Interpreting%20the%20National%20Electrical%20Code.pdf
Re: L6-20P - L6-30R
On Wed, Mar 19, 2014 at 2:19 PM, Chuck Anderson c...@wpi.edu wrote: On Wed, Mar 19, 2014 at 02:05:42PM -0400, William Herrin wrote: 50 watts DC. It won't electrocute you (that's AC) but it's the same power that makes a 40 watt bulb burning hot. I don't know where you are getting your facts, but 802.3af maxes out at 15.4W and 802.3at at 34.2W, and DC can electrocute you just as well as AC. http://en.wikipedia.org/wiki/Power_over_Ethernet#Standard_implementation Hi Chuck, Same article where you got your facts: Up to a theoretical 51 watts is available for a device. Though technically it's newer PoE standards than AF which hit 51 watts. Electrocution is a heart attack induced when alternating current disrupts the heart's normal sinus rhythm. DC can burn you but it won't disrupt your heart rhythm, hence it won't electrocute you. That was the basis Edison's theater with the electric chair when he argued against the safety of Tesla's AC current. Regards, Bill Herrin -- William D. Herrin her...@dirtside.com b...@herrin.us 3005 Crane Dr. .. Web: http://bill.herrin.us/ Falls Church, VA 22042-3004
Re: L6-20P - L6-30R
On 3/19/14, 10:21, Jay Ashworth wrote: It is exactly that: no one says you*can't* wire a 20A branch circuit with #10. It is even*possible*, though unlikely, that if you did so, you wouldn't have to derate it to 80%. I would have to reread the Code to be sure. Well, I'd say it's pretty likely. However highly unlikely to be code-worthy of slapping on a 30A breaker in place of a 20. 10-20 CCCs in a raceway or cable is a 50% derating, so if those conductors were for 20A branch circuits it would have to be 10AWG, not 12 since with 10AWG you're derating from 40A. But the max protective device on 10AWG is 30A unless permitted by 240.4. Even 7-9 CCCs in a raceway or cable derates 10AWG to 28A (70%), so while still suitable for a 20A breaker it's not for 30A. Max would be 6 CCCs to stay at 80% derating (4-6 CCCs). ~Seth
Re: L6-20P - L6-30R
Jay Ashworth j...@baylink.com writes: It is exactly that: no one says you *can't* wire a 20A branch circuit with #10. It is even *possible*, though unlikely, that if you did so, you wouldn't have to derate it to 80%. I would have to reread the Code to be sure. It's not the conductor that you're derating; it's the breaker. Per NEC Table 310.16, ampacity of #12 copper THHN/THWN2 (which is almost certainly what you're pulling) with 3 conductors in a conduit is 30 amps. Refer to Table 310.15(B)(2)(a) for derating of more than 3 current-carrying conductors in a conduit. 4-6 is 80%, 7-9 is 70%. Plenty good for 20 amps for any conceivable number of conductors in a datacenter whip. Thermal breakers are typically deployed in an 80% application for continuous loads, per NEC 384-16(c). See the references to 125% of continuous load, which of course is the reciprocal of 80%. http://cliffordpower.com/wp/wp-content/uploads/2010/08/CPS_info_sheet_37_CB_80_versus_100.pdf -r
Re: L6-20P - L6-30R
On 3/19/2014 7:00 AM, Alex Rubenstein wrote: Go look at any standard household lamp. It has a 5-15P on the end of it, which could be plugged into an outlet rated for 20 amps (5-20R), with 16 gauge lamp cord rated for 10 amps or less. Mine all seem to be NEMA 1-15P, some (most?) with 18 AWG wire. Have I been shortchanged? :) I wrote that too fast, you are absolutely right. But my point remains. Appliance/load wire size is often, and many times smaller than the ampacity of the circuit. Heck, how many times have you plugged in a 14 gauge extension cord to a 5-20R? I believe the thinking behind the standards is that the breaker is sized to protect the wiring to the receptacle or fixture. After that you are on your own. It is always safe to demand less current than the circuit is designed to provide. It is never save to deform connectors. Changing a receptacle to one of a lower capacity is safe, if confusing to those who follow you. If I operated a facility I would offer short adapters cords rather that changing the receptacle. -- Requiescas in pace o email Two identifying characteristics of System Administrators: Ex turpi causa non oritur actio Infallibility, and the ability to learn from their mistakes. (Adapted from Stephen Pinker)
Re: L6-20P - L6-30R
- Original Message - From: Alex Rubenstein a...@corp.nac.net And to Jay: Network cables most certainly do carry power. No, they carry signal, which is considerably different - unless of course it is 802.1af. That's what he meant, yes, and a couple other people made the point as well. 1af is 48VDC *precisely* to make it remain Low Voltage, which takes it outside the realm of NEC[1], and hence, UL. Cheers, -- jra [1] Yes, yes, except section 800. -- Jay R. Ashworth Baylink j...@baylink.com Designer The Things I Think RFC 2100 Ashworth Associates http://www.bcp38.info 2000 Land Rover DII St Petersburg FL USA BCP38: Ask For It By Name! +1 727 647 1274
Re: L6-20P - L6-30R
- Original Message - From: Seth Mattinen se...@rollernet.us On 3/19/14, 10:21, Jay Ashworth wrote: It is exactly that: no one says you*can't* wire a 20A branch circuit with #10. It is even*possible*, though unlikely, that if you did so, you wouldn't have to derate it to 80%. I would have to reread the Code to be sure. Well, I'd say it's pretty likely. However highly unlikely to be code-worthy of slapping on a 30A breaker in place of a 20. Well, the situation were were discussing was replacing 30A CB -- 10 AWG -- L6-30 with 20A CB -- 10 AWG -- L6-20 and as I was reminded, you'd still have to derate that unless the CB was magnetic. And you can't leave the breaker at 30, cause then the attached 20A single device isn't protected properly by it. So I was worng on the derating. Cheers, -- jra -- Jay R. Ashworth Baylink j...@baylink.com Designer The Things I Think RFC 2100 Ashworth Associates http://www.bcp38.info 2000 Land Rover DII St Petersburg FL USA BCP38: Ask For It By Name! +1 727 647 1274
Re: L6-20P - L6-30R
They're different. You can't force them. On Tue, Mar 18, 2014 at 12:24 PM, Randy a...@djlab.com wrote: I have a situation where a 208v/20A PDU (L6-20P) is supposedly hooked to a 208v/30A circuit (L6-30R). Before I order the correct PDU's and whip cords...sanity check...are connectors 'similar' enough that this is possible (with force) or am I going to find we've actually got L6-20R's on the provider side? -- ~Randy -- 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
Re: L6-20P - L6-30R
The whole point behind the locking connectors (like the IEC connectors) is to prevent you from plugging the wrong connectors together. Not only are the different dimensions, but the prongs are keyed differently as well. If you put a L6-20P device into a L6-30R, then it was done by physically replacing the plug on the PDU, not by making it work. I have had to do this at times but it is not strictly allowed by codes and not at all recommended. -Wayne On Tue, Mar 18, 2014 at 03:46:26PM -0700, Mike Hale wrote: They're different. You can't force them. On Tue, Mar 18, 2014 at 12:24 PM, Randy a...@djlab.com wrote: I have a situation where a 208v/20A PDU (L6-20P) is supposedly hooked to a 208v/30A circuit (L6-30R). Before I order the correct PDU's and whip cords...sanity check...are connectors 'similar' enough that this is possible (with force) or am I going to find we've actually got L6-20R's on the provider side? -- ~Randy -- 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0 --- Wayne Bouchard w...@typo.org Network Dude http://www.typo.org/~web/
Re: L6-20P - L6-30R
* w...@typo.org (Wayne E Bouchard) [Tue 18 Mar 2014, 23:53 CET]: I have had to do this at times but it is not strictly allowed by codes and not at all recommended. It's an active fire hazard. The cables aren't rated (= built) for the power draw. -- Niels.
Re: L6-20P - L6-30R
The connectors are definitely distinct and incompatible, you won't be able to force a 20 into a 30 or vice versa. So yes, one of the ends has been changed. M. Original Message From: Randy Sent: Tuesday, March 18, 2014 18:42 To: nanog@nanog.org Reply To: a...@djlab.com Subject: L6-20P - L6-30R I have a situation where a 208v/20A PDU (L6-20P) is supposedly hooked to a 208v/30A circuit (L6-30R). Before I order the correct PDU's and whip cords...sanity check...are connectors 'similar' enough that this is possible (with force) or am I going to find we've actually got L6-20R's on the provider side? -- ~Randy
Re: L6-20P - L6-30R
https://www.21cii.com/ITStudio/Content/Resources/Images/Appendix/Plug%20%20Power/SB%202P-3W_505x447.png I think the 250 v 15 amp plugs fit in the 20 amp sockets, but the 20s don't fit in the 30 sockets. This sort of thing is usually an adapter, a little cylinder with a L6-20R on one end and a L6-30P on the other, since the loads are safe. Either that, or a short jumper cable wired the same way. On Tue, Mar 18, 2014 at 3:46 PM, Mike Hale eyeronic.des...@gmail.comwrote: They're different. You can't force them. On Tue, Mar 18, 2014 at 12:24 PM, Randy a...@djlab.com wrote: I have a situation where a 208v/20A PDU (L6-20P) is supposedly hooked to a 208v/30A circuit (L6-30R). Before I order the correct PDU's and whip cords...sanity check...are connectors 'similar' enough that this is possible (with force) or am I going to find we've actually got L6-20R's on the provider side? -- ~Randy -- 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0 -- -george william herbert george.herb...@gmail.com
Re: L6-20P - L6-30R
Randy a...@djlab.com wrote: I have a situation where a 208v/20A PDU (L6-20P) is supposedly hooked to a 208v/30A circuit (L6-30R). Before I order the correct PDU's and whip cords...sanity check...are connectors 'similar' enough that this is possible (with force) or am I going to find we've actually got L6-20R's on the provider side? They are slightly different. http://www.stayonline.com/detail.aspx?id=6772 http://www.stayonline.com/detail.aspx?id=6775 -- andrei
Re: L6-20P - L6-30R
Crap, was looking at the non-locking ones. Ignore that. On Tue, Mar 18, 2014 at 3:54 PM, George Herbert george.herb...@gmail.comwrote: https://www.21cii.com/ITStudio/Content/Resources/Images/Appendix/Plug%20%20Power/SB%202P-3W_505x447.png I think the 250 v 15 amp plugs fit in the 20 amp sockets, but the 20s don't fit in the 30 sockets. This sort of thing is usually an adapter, a little cylinder with a L6-20R on one end and a L6-30P on the other, since the loads are safe. Either that, or a short jumper cable wired the same way. On Tue, Mar 18, 2014 at 3:46 PM, Mike Hale eyeronic.des...@gmail.comwrote: They're different. You can't force them. On Tue, Mar 18, 2014 at 12:24 PM, Randy a...@djlab.com wrote: I have a situation where a 208v/20A PDU (L6-20P) is supposedly hooked to a 208v/30A circuit (L6-30R). Before I order the correct PDU's and whip cords...sanity check...are connectors 'similar' enough that this is possible (with force) or am I going to find we've actually got L6-20R's on the provider side? -- ~Randy -- 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0 -- -george william herbert george.herb...@gmail.com -- -george william herbert george.herb...@gmail.com
RE: L6-20P - L6-30R
I've had to do that before; provider gave me a 208v/30a circuit and I already had a power strip I wanted to re-use that had a corded L6-20P connector on it. I purchased a L6-30P plug / L6-20R receptacle adapter from http://www.stayonline.com/nema-locking-6-30-amp-adapters.aspx They're only $25 and they ship overnight if needed. They have one foot cabled versions of the same thing too if you have tight working space and there's not enough room for both connectors back to back; works as a strain relief too so maybe that option is better regardless. If you're trying to go the other direction, plugging an L6-30P into an L6-20R 20 amp circuit, that I'd recommend against because it never fails that someone says hey, 30 amp power strip, let me plug some more stuff into it not realizing it's on a 20 amp breakered circuit, then all your stuff goes down while you try to find the facility staff to reset the breaker. David -Original Message- From: Randy [mailto:a...@djlab.com] Sent: Tuesday, March 18, 2014 3:25 PM To: nanog@nanog.org Subject: L6-20P - L6-30R I have a situation where a 208v/20A PDU (L6-20P) is supposedly hooked to a 208v/30A circuit (L6-30R). Before I order the correct PDU's and whip cords...sanity check...are connectors 'similar' enough that this is possible (with force) or am I going to find we've actually got L6-20R's on the provider side? -- ~Randy
Re: L6-20P - L6-30R
On Tue, 18 Mar 2014, Randy wrote: I have a situation where a 208v/20A PDU (L6-20P) is supposedly hooked to a 208v/30A circuit (L6-30R). Before I order the correct PDU's and whip cords...sanity check...are connectors 'similar' enough that this is possible (with force) or am I going to find we've actually got L6-20R's on the provider side? Generally, all common electrical plugs and receptacles (straight-blade, twist-lock, IEC, and CEE) are physically sized and keyed differently, so that they can't be connected together, to keep people from connecting loads that require a specific voltage/current to supplies that aren't intended to provide it. While it's not uncommon for someone to replace a plug with the right kind, this can (in order of badness): 1. start a fire 2. short out and (hopefully) trip a breaker - that's what breakers are for! 3. violate building/electrical codes 4. void your device's warranty As others have mentioned, just making it work, rather than making it work correctly, can be bad news. People often fancy themselves unlicensed/uncertified electricians. I've seen some of the handiwork from such people, and while their creativity is impressive, having to rip their stuff out and re-do it is not fun. jms
Re: L6-20P - L6-30R
- Original Message - From: Randy a...@djlab.com I have a situation where a 208v/20A PDU (L6-20P) is supposedly hooked to a 208v/30A circuit (L6-30R). Before I order the correct PDU's and whip cords...sanity check...are connectors 'similar' enough that this is possible (with force) or am I going to find we've actually got L6-20R's on the provider side? As it happens, the chart at http://www.stayonline.com/reference-nema-locking.aspx suggests that the L6-20 and L6-30 are less different than you'd expect. I *think* those are on different diameters, and a datacenter employee ought to friggin' know better... but I don't think it's 100% impossible that this has happened. If it did, you're gonna replace the plug anyway... As long as there's a 20A breaker on the PDU, you're safe, if not within code. Cheers, -- jra -- Jay R. Ashworth Baylink j...@baylink.com Designer The Things I Think RFC 2100 Ashworth Associates http://www.bcp38.info 2000 Land Rover DII St Petersburg FL USA BCP38: Ask For It By Name! +1 727 647 1274
Re: L6-20P - L6-30R
On 18-Mar-14 17:54, Niels Bakker wrote: * w...@typo.org (Wayne E Bouchard) [Tue 18 Mar 2014, 23:53 CET]: I have had to do this at times but it is not strictly allowed by codes and not at all recommended. It's an active fire hazard. The cables aren't rated (= built) for the power draw. That's a problem in the other direction, but plugging a 20A device into a 30A feed shouldn't be a hazard at all. S -- Stephen Sprunk God does not play dice. --Albert Einstein CCIE #3723 God is an inveterate gambler, and He throws the K5SSSdice at every possible opportunity. --Stephen Hawking smime.p7s Description: S/MIME Cryptographic Signature
RE: L6-20P - L6-30R
Strictly speaking, no, you cannot do this. The diameter of the pattern of the pins are different 20 to 30 amps. If no electrical inspectors are looking, yes, you can bend the pins and make it work. I've done it, others have done it, but you shouldn't do it and it is a clear electrical code violation. Go to Lowes or Home Depot, but the right end, and stick it on there. You do still have the issue where the wire size is wrong, but if you have a brain and don't overload it, you will be OK. But, this too is still a clear electrical code violation. I have a situation where a 208v/20A PDU (L6-20P) is supposedly hooked to a 208v/30A circuit (L6-30R). Before I order the correct PDU's and whip cords...sanity check...are connectors 'similar' enough that this is possible (with force) or am I going to find we've actually got L6-20R's on the provider side? -- ~Randy
RE: L6-20P - L6-30R
Go look at any standard household lamp. It has a 5-15P on the end of it, which could be plugged into an outlet rated for 20 amps (5-20R), with 16 gauge lamp cord rated for 10 amps or less. It all depends on the connected load. * w...@typo.org (Wayne E Bouchard) [Tue 18 Mar 2014, 23:53 CET]: I have had to do this at times but it is not strictly allowed by codes and not at all recommended. It's an active fire hazard. The cables aren't rated (= built) for the power draw. -- Niels.
Re: L6-20P - L6-30R
On 03/18/2014 7:11 pm, Jay Ashworth wrote: As it happens, the chart at http://www.stayonline.com/reference-nema-locking.aspx suggests that the L6-20 and L6-30 are less different than you'd expect. I *think* those are on different diameters, and a datacenter employee ought to friggin' know better... but I don't think it's 100% impossible that this has happened. If it did, you're gonna replace the plug anyway... I plan on installing the correct PDU/cords shortly so no adapter should be needed, assuming it's really a L6-30R on the provider end. Disclaimer -- I never intended to break any codes, it was an oversight by me sending the wrong PDU, and onsite staff should have know better before hooking it up. -- ~Randy
Re: L6-20P - L6-30R
- Original Message - On 18-Mar-14 17:54, Niels Bakker wrote: * w...@typo.org (Wayne E Bouchard) [Tue 18 Mar 2014, 23:53 CET]: I have had to do this at times but it is not strictly allowed by codes and not at all recommended. It's an active fire hazard. The cables aren't rated (= built) for the power draw. That's a problem in the other direction, but plugging a 20A device into a 30A feed shouldn't be a hazard at all. Unless the device you are plugging in does not have its own breaker. If it doesn't, then your 20A cord could catch on fire before the 30A breaker trips. Not incredibly likely, but possible. -Randy
Re: L6-20P - L6-30R
- Original Message - From: Stephen Sprunk step...@sprunk.org On 18-Mar-14 17:54, Niels Bakker wrote: * w...@typo.org (Wayne E Bouchard) [Tue 18 Mar 2014, 23:53 CET]: I have had to do this at times but it is not strictly allowed by codes and not at all recommended. It's an active fire hazard. The cables aren't rated (= built) for the power draw. That's a problem in the other direction, but plugging a 20A device into a 30A feed shouldn't be a hazard at all. Plugging a 20A *PDU* into a 30A receptacle can be dangerous if a) there is more than 20A of load plugged into it b) it has no breaker, and c) the cordset is only 12A, which is what you would expect on a 20A PDU. Cheers, -- jr 'up the voltage' a -- Jay R. Ashworth Baylink j...@baylink.com Designer The Things I Think RFC 2100 Ashworth Associates http://www.bcp38.info 2000 Land Rover DII St Petersburg FL USA BCP38: Ask For It By Name! +1 727 647 1274
Re: L6-20P - L6-30R
It's temporary unless it works. -Laszlo On Mar 18, 2014, at 11:30 PM, Jay Ashworth j...@baylink.com wrote: - Original Message - From: Stephen Sprunk step...@sprunk.org On 18-Mar-14 17:54, Niels Bakker wrote: * w...@typo.org (Wayne E Bouchard) [Tue 18 Mar 2014, 23:53 CET]: I have had to do this at times but it is not strictly allowed by codes and not at all recommended. It's an active fire hazard. The cables aren't rated (= built) for the power draw. That's a problem in the other direction, but plugging a 20A device into a 30A feed shouldn't be a hazard at all. Plugging a 20A *PDU* into a 30A receptacle can be dangerous if a) there is more than 20A of load plugged into it b) it has no breaker, and c) the cordset is only 12A, which is what you would expect on a 20A PDU. Cheers, -- jr 'up the voltage' a -- Jay R. Ashworth Baylink j...@baylink.com Designer The Things I Think RFC 2100 Ashworth Associates http://www.bcp38.info 2000 Land Rover DII St Petersburg FL USA BCP38: Ask For It By Name! +1 727 647 1274
Re: L6-20P - L6-30R
On Tue, Mar 18, 2014 at 6:54 PM, Niels Bakker niels=na...@bakker.net wrote: * w...@typo.org (Wayne E Bouchard) [Tue 18 Mar 2014, 23:53 CET]: I have had to do this at times but it is not strictly allowed by codes and not at all recommended. It's an active fire hazard. The cables aren't rated (= built) for the power draw. Meh. It depends. Plug that 30 amp power strip into a 20 amp circuit. Try to use more than 20 amps and the main breaker trips. No problem. Plug that 20 amp power strip into a 30 amp circuit. Try to use more than 20 amps and the strip's breaker trips. No problem. Get a short before the strip breaker and the main breaker trips before the wires can heat. There just aren't a whole lot of failure modes here that result in fire short of one or the other breaker failing. And that results in fire regardless of the amperage mismatch. This, by the way, is why you're allowed to plug that 22 gauge Christmas light wire into a 15 amp receptacle even though it can't handle 15 amps: the 3 amp fuse will blow if there's a short. Just don't plug in anything with lower-rated wire that doesn't have its own breaker or fuse. Regards, Bill Herrin -- William D. Herrin her...@dirtside.com b...@herrin.us 3005 Crane Dr. .. Web: http://bill.herrin.us/ Falls Church, VA 22042-3004
Re: L6-20P - L6-30R
On 3/18/2014 2:24 PM, Randy wrote: I have a situation where a 208v/20A PDU (L6-20P) is supposedly hooked to a 208v/30A circuit (L6-30R). Before I order the correct PDU's and whip cords...sanity check...are connectors 'similar' enough that this is possible (with force) or am I going to find we've actually got L6-20R's on the provider side? http://www.amazon.com/L6-20P-L6-30R-Locking-Power-Adapter/dp/B004W359W0 -- Requiescas in pace o email Two identifying characteristics of System Administrators: Ex turpi causa non oritur actio Infallibility, and the ability to learn from their mistakes. (Adapted from Stephen Pinker)
Re: L6-20P - L6-30R
On Tue, Mar 18, 2014 at 09:39:46PM -0400, William Herrin wrote: There just aren't a whole lot of failure modes here that result in fire short of one or the other breaker failing. And that results in fire regardless of the amperage mismatch. This, by the way, is why you're allowed to plug that 22 gauge Christmas light wire into a 15 amp receptacle even though it can't handle 15 amps: the 3 amp fuse will blow if there's a short. Just don't plug in anything with lower-rated wire that doesn't have its own breaker or fuse. Regards, Bill Herrin And that is the result of the way things have been set down. The electrical code (as well as just general common sense) requires that there are multiple levels of protection specifically to try to avoid weird failure modes. So what we end up with is wire that is overrated for the current it is supposed to carry, multiple fusable links inbetween point A and point B and a grounding system that is supposed to safely direct voltage away from people in the event that everything else fails. So back to what I said before, I don't like doing stuff like that and don't advocate it if for no other reason that it makes good sense not to put yourself into a potentially problematic situation. -Wayne --- Wayne Bouchard w...@typo.org Network Dude http://www.typo.org/~web/
Re: L6-20P - L6-30R
On 3/18/2014 6:11 PM, Jay Ashworth wrote: From: Randy a...@djlab.com I have a situation where a 208v/20A PDU (L6-20P) is supposedly hooked to a 208v/30A circuit (L6-30R). Before I order the correct PDU's and whip cords...sanity check...are connectors 'similar' enough that this is possible (with force) or am I going to find we've actually got L6-20R's on the provider side? As it happens, the chart at http://www.stayonline.com/reference-nema-locking.aspx suggests that the L6-20 and L6-30 are less different than you'd expect. I *think* those are on different diameters, and a datacenter employee ought to friggin' know better... but I don't think it's 100% impossible that this has happened. If it did, you're gonna replace the plug anyway... As long as there's a 20A breaker on the PDU, you're safe, if not within code. From experience with some electricians who couldn't follow simple written instructions, it is physically possible to put an L6-20 plug into an L6-30 receptacle. But it won't lock into place. Beyond all the other reasons it's not recommended, the slightest bump of the cable will likely knock it loose causing whatever is on there to drop. (Cue electricans knocking the production 6506E's offline 3 times in 20 minutes while they were replacing the breakers and the supposedly redundant power cords...) If you can unplug it to look, every one I've ever seen has had the voltage and amperage clearly molded into the face of it. Jeremy TheBrez Bresley b...@brezworks.com
