At 06:10 AM 8/23/2004 +0000, you wrote: >--- In biofuel@yahoogroups.com, "josephputzer" <[EMAIL PROTECTED]> >wrote: >Hello all, > >I've just begun to build a processor out of two 55 gallon drums. I >am having a 1" bushing welded to the drum so that I can put a screw- >in heating element into the processor. I wanted the bushing so that >I can take out the element for cleaning and whatnot. My trouble is >that I'm not much for electrical components. I have a 4.5 kw 240 v >element. How do I safely attach a power cord with the given wattage >and voltage? Is 4.5 kw to high? Should I find a 1.5 or 2.0 kw element >instead? > >Any help would be great! >--- End forwarded message ---
I think I described this at www.veggieavenger.com/media in the 'appleseed processor- open source plans' thread. Without going into all the details of how normal wiring is done (please go buy a $10 book on wiring, it'll help a lot with the basics of wire stripping and how to make connections) here are a few pointers on water heater heating elements: 4.5 KW is fine, assuming that the wiring you use is adequate and that the circuit is designed for it. 4.5 KW is 4500 watts, and divided by 240 volts you will be drawing 18.75 amps. That amperage isn't too bad- so use 12 gauge wire/cable or heavier (like 10 gauge) (i use something that we generically call 'spa cable' - black waterproof flexible cable sold at Home Depot, but I'm not sure what it's technical name actually is!). You can also use 12 gauge extension cord wiring- make sure it's actually 12 gauge, not just some kind of so-called 'heavy-duty' extension cord (this is a form of wire sold by the foot at hardware stores, you don't have to cut up an existing extension cord which you might not know the gauge of) Don't draw any other loads on that wiring if it's only 12 gauge (which is designed for 20 amps maximum, assuming it's under 100 feet in length). 10 gauge is designed for up to 30 amps. Presuming that you have 240 service at the site where you will be installing the processor, yOu will need to wire the cord to a plug that matches your 240V outlet (there many types of plug configurations for 240v), or wire the cord into a disconnect box (grey subpanel looking thing which has a sort of big on-off Frankenstein switch on the side) and then wire that disconnect into a plug or somehow into your 240V service (ie see the wiring book you should buy if you want to go fancy like this). modern 240V plugs come with either a four-wire or a three-wire configuration. YOu only need three wires, but if your existing outlet is a four-wire (ie like from a dryer or range), go buy that same type of plug and don't wire anything to it's fourth 'neutral' terminal (the box directions should explain which is what). four-wire 240 plugs are meant for appliances that have both a 240V heater and a 120V timer or clock, so missing the neutral in this case won't do any harm. The actual heating element end gets wired like this: black and white wires are wired to the two terminals of the heating element. Here's the confusing part: in 240V service, what you're supposed to be using for the element is a black and a red, but we're using a black and a white because that's all our hardware store cord gives us. In our case, if you just bought some spa cable or extension cord type cable, you don't have a black and a red. SO you use the black and the white, and pretend that the white is a red (electricians are supposed to paint red the ends of the white if doing something similar to this so that future electricians dont' get confused). You will also have a green wire in the cord, and that must get grounded to the drum. If you're welding anyway, add yourself a little tab to the drum, near the heating element, then use a sheet metal screw to make a ground terminal for the green wire to land on. If you're done with your welding and it's too late, then make yourself a c-clamp with a little threaded hole in it, and use a screw to make a terminal for the green wire. Then clamp it securely to the bottom lip of the drum or some other secure location. The plug end: your plug terminals are labeled either on the box or on the plug itself. You should wire the black and the white (supposed to be red actually) to the 'load' terminals (they might be brass colored), and the green to the 'ground' terminal (might be green colored). If you have a fourth terminal for 'neutral', ignore it. Normally the neutral is where the white wire goes in a four-wire cord (three plus a ground), but that's not what you're using it for in a three-wire (two plus ground) cord. It's OK to leave it blank. The other thing you could do, is to run that heating element at 120V- just wire a normal 120V plug onto it (which some hardware store clerks can tell you how to do). At 120V, the element will run at 1`/4 the wattage, which will make it a 1000 watt approximately, which will be a little low-power for a 55 gallon drum, but you can either buy a 120V, 1500 watt element, or something like that if you're worried about wiring 240 or dont' have 240 service handy. Wiring a 120V heating element (or using a 240V one at 120V) works like this: heavy duty grounded ordinary 120V plug has a brass and a silver screw, and a green screw. In our case, wire the white and the black wires to the two terminals of the heating element side, then take the black wire and attach it to the brass screw on the 120V plug, and take the white wire and attach it to the silver terminal on the plug. The green wire goes between the ground on the reactor and the green terminal on the plug. Hope that wasn't too confusing, mark ********* www.LocalB100.com www.veggieavenger.com/media - open-design homebrew biodiesel equipment plans www.groups.yahoo.com/group/local-b100-biz -biodiesel co-ops and biodiesel small business discussion forum www.groups.yahoo.com/group/biodieselbasics -the alternative Yahoo biodiesel list ------------------------ Yahoo! Groups Sponsor --------------------~--> $9.95 domain names from Yahoo!. Register anything. http://us.click.yahoo.com/J8kdrA/y20IAA/yQLSAA/FGYolB/TM --------------------------------------------------------------------~-> Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://infoarchive.net/sgroup/biofuel/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Yahoo! 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