Re: Wiring under raised floors
Cables under raised floors are currently the subject of a proposal to change the code regarding them as follows: 12-101 -( 645-5(d)(5)): SUBMITTER: Rick Zupan, Lake Oswego, OR RECOMMENDATION: Revise as follows: 645-5(d)(5) Cable, other than those covered in (b) and (2) and those complying with (a), (b) and (c) below, shall be listed as type DP cable having adequate fire-resistant characteristics suitable for use under raised floors of an information technology equipment room. SUBSTANTIATION: The local authority having jurisdiction has decided that barring explicit language allowing it flexible cords cannot be used to plug into underfloor receptacles, this should correct this. The NEC code panel 12 statement in response reads: Requirements for the use of listed DP cable were put into the NEC because of the panel's concerns that cables under the raised floor should pass the vertical flame test. Permitting other than DP cables would not fall within the purpose of the Code as outlined in 90-1. The Code already contains explicit language prohibiting the use of other than DP-type cable. This response is open for comment and will be acted upon in a meeting in December regarding disposition of this and other proposed changes to the NEC. Comments MUST be received by NFPA by 27 Oct 00. To comment, see http://www.nfpa.org/submitterapp2.html For other code information see http://www.nfpa.org/Codes/ My personal views are as follows: The panel statement says that only DP cables but not flexible cords are permitted beneath raised floors. This is historically incorrect. - The allowance of receptacles beneath raised floors, 645-5(d)(2), prior to the development of DP cables has always implied flexible cords would be permitted below raised floors in order to plug into those receptacles. - DP cables have not been intended for use as power cords. They were introduced recently to the code and ITE standards for use as interconnecting cables. - Type DP cables are not present in article 400, are not hard service cord types, and therefore would not be usable for power cords on machines outside computer rooms. Manufacturers would have to either market two machine types or institute cord replacement in the field. Field rewiring is significantly less safe and dependable than that done and tested in manufacturing facilities. - During the introduction of DP cables it was never mentioned that DP cables were required to replace flexible cords. Prohibiting the use of flexible cords for power cords below raised floors, if it is desired by the committee, should be the subject of a new proposal with full consideration of its impact on current installations and providing a timetable for implementation. - No current products or installations use DP cables for power cords since such construction is not allowed by UL 1950. The only power cords presently permitted by UL 1950 for floor mounted equipment are: SJ, SJE, SJO, SJOO, SJT, SJTO, SVTOO, S, SE, SO, SOO, ST, STO, STOO. - The interpretation that only DP cables could be used for power cordage below raised floors would result in placement of receptacles and power cords above the floor, increasing trip hazards and increasing the risk of damage to cords. - Rejecting this proposal with the publication of the current panel statement would have the result of a change to the code and current usage. - Standard power cords run below raised floors constitutes essentially 100% of current usage and has not been shown to be a problem. I recommend accepting 12-101 as a correction to an error in the current code. ted.eck...@apcc.com wrote: Is it permissible to place electrical receptacles under the raised floor of a computer room? Can power cords pass through openings in the raised floor or do all power connections need to be in conduit? I have received two opinions; one stating that receptacles must be accessible above floor level and the other stating that receptacles can be placed below the floor. The United States National Electrical Code is a bit vague on the subject, although Article 645-5 (d) (2) seems to imply that conduit is only required up to the receptacle. I can find no references to raised floor installations in the Canadian Electrical Code or BS 7671, IEE Wiring Regulations. Ted Eckert Regulatory Compliance Engineer American Power Conversion Corporation ted.eck...@apcc.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: Wiring under raised floors
Hi Ted, If I recall correctly, another code concern might be that pluggable items are intended to be accessible so they can be unplugged in the event of fire or shock. If the outlet is under a floor it cannot be seen, and cannot be accessed easily for disconnection. Mike Harris -Original Message- From: Peter Tarver ptar...@nortelnetworks.com To: emc-p...@ieee.org emc-p...@ieee.org Date: Wednesday, September 20, 2000 8:48 AM Subject: RE: Wiring under raised floors Ted - At issue, really, is whether or not the under side of the raised floor is used for environmental air, not simply that it's in a computer room. For the question at hand, though, I'll assume that's the case. My first inclination is to say it's not allowed. If you also look at 300-22 of the NEC, you'll note that devices generally aren't allowed in environmental air spaces. However, if the devices are used in the other spaces loosely described in 300-22(c), there's the option of the device being certified for the application. I can imagine receptacles being made entirely of thermosetting materials that could quite possibly comply with the relevant requirements (say, in UL910) and being allowed under the raised floor. Ultimately, though, it comes down to what the local Authority Having Jurisdiction has to say about an installation. Some may argue against your scenario, while others may not care. Regards, Peter L. Tarver, PE ptar...@nortelnetworks.com -Original Message- From: ted.eck...@apcc.com [mailto:ted.eck...@apcc.com] Sent: Wednesday, September 20, 2000 2:12 PM Is it permissible to place electrical receptacles under the raised floor of a computer room? Can power cords pass through openings in the raised floor or do all power connections need to be in conduit? I have received two opinions; one stating that receptacles must be accessible above floor level and the other stating that receptacles can be placed below the floor. The United States National Electrical Code is a bit vague on the subject, although Article 645-5 (d) (2) seems to imply that conduit is only required up to the receptacle. I can find no references to raised floor installations in the Canadian Electrical Code or BS 7671, IEE Wiring Regulations. Ted Eckert
Re: Wiring under raised floors
ted.eck...@apcc.com wrote: Is it permissible to place electrical receptacles under the raised floor of a computer room? Can power cords pass through openings in the raised floor or do all power connections need to be in conduit? I have received two opinions; one stating that receptacles must be accessible above floor level and the other stating that receptacles can be placed below the floor. The United States National Electrical Code is a bit vague on the subject, although Article 645-5 (d) (2) seems to imply that conduit is only required up to the receptacle. I can find no references to raised floor installations in the Canadian Electrical Code or BS 7671, IEE Wiring Regulations. Ted, In order that your company NEVER have any problems with this issue ever, you will have to follow NEC 645-5 to the letter. Ultimately, it's up to the interpretation of the local inspector. Having been called on the rug about this very issue from just one customer within the past year, my *suggestion* is: Do NOT put ANY power cords under a raised floor no matter if it's a plenum issue or not and no matter how long or short that power cord may be - none. Unless of course you can procure the style power cord required by the standard. And good luck with that. - Regards, Doug McKean --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: Wiring under raised floors
Ted - At issue, really, is whether or not the under side of the raised floor is used for environmental air, not simply that it's in a computer room. For the question at hand, though, I'll assume that's the case. My first inclination is to say it's not allowed. If you also look at 300-22 of the NEC, you'll note that devices generally aren't allowed in environmental air spaces. However, if the devices are used in the other spaces loosely described in 300-22(c), there's the option of the device being certified for the application. I can imagine receptacles being made entirely of thermosetting materials that could quite possibly comply with the relevant requirements (say, in UL910) and being allowed under the raised floor. Ultimately, though, it comes down to what the local Authority Having Jurisdiction has to say about an installation. Some may argue against your scenario, while others may not care. Regards, Peter L. Tarver, PE ptar...@nortelnetworks.com -Original Message- From: ted.eck...@apcc.com [mailto:ted.eck...@apcc.com] Sent: Wednesday, September 20, 2000 2:12 PM Is it permissible to place electrical receptacles under the raised floor of a computer room? Can power cords pass through openings in the raised floor or do all power connections need to be in conduit? I have received two opinions; one stating that receptacles must be accessible above floor level and the other stating that receptacles can be placed below the floor. The United States National Electrical Code is a bit vague on the subject, although Article 645-5 (d) (2) seems to imply that conduit is only required up to the receptacle. I can find no references to raised floor installations in the Canadian Electrical Code or BS 7671, IEE Wiring Regulations. Ted Eckert
RE: Wiring under raised floors
Section 645-5 of the United States National Electrical Code states that the branch-circuit conductors must be in conduit. If these branch circuits feed a receptacle, it is acceptable for the receptacle to be located under the floor so long as the receptacle is accessible (i.e. a floor panel can be easily removed) and that the power cord is type DP (other type designations are listed in the code as well, I leave it to others to describe the differences). I have seen computer rooms in the US with receptacles located below the raised floor and not heard of any issues. I think the bigger issue is that of having power and signal cables in the same proximity causing EMI type problems. -Original Message- From: ted.eck...@apcc.com [mailto:ted.eck...@apcc.com] Sent: Wednesday, September 20, 2000 9:12 AM To: emc-p...@ieee.org Subject: Wiring under raised floors Is it permissible to place electrical receptacles under the raised floor of a computer room? Can power cords pass through openings in the raised floor or do all power connections need to be in conduit? I have received two opinions; one stating that receptacles must be accessible above floor level and the other stating that receptacles can be placed below the floor. The United States National Electrical Code is a bit vague on the subject, although Article 645-5 (d) (2) seems to imply that conduit is only required up to the receptacle. I can find no references to raised floor installations in the Canadian Electrical Code or BS 7671, IEE Wiring Regulations. Ted Eckert Regulatory Compliance Engineer American Power Conversion Corporation ted.eck...@apcc.com The items contained in this e-mail reflect the personal opinions of the writer and are only provided for the assistance of the reader. The writer is not speaking in an official capacity for APC nor representing APC's official position on any matter. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
