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Don,
I think what the existing circuit doesn’t have is an equipment grounding conductor. The neutral “served” as the ground and neutral (which is to say, there was really no equipment grounding conductor at all). This was Code-compliant until recently (the ’96 Code as I recall).
I agree with Andrew that you will be a lot safer if you have a separate neutral and equipment grounding conductors. One way is to run new cable. The other is to run a new EGC, which must be tied to the ground bar at the panel. It must follow essentially the same path as the current-carrying conductors, and be protected from physical damage. Also, it’s no longer acceptable to run a ground to the closest water pipe…
Aluminum conductors are just fine for applications like this. Do use the anti-ox paste, and make sure that the terminals are torqued to specifications. If you don’t splice the conductors, then you won’t need the compression splice tooling that Casey “heard of”. (right-on Beckman).
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I'm replacing my old oven, and found that I don't have a neutral wire to the box. I guess it wasn't required in 1988 where I live (?). It's on it's own 50 Amp breaker with #6 wire. Can I get away with wiring the appliance ground and neutral to the supply ground?
Also, it is aluminum wire (though the other wiring in the house is copper). Do I need to take any special precautions other than to make sure I use the anti-oxidant goop?
*"NO." Neutral and ground MUST be kept separate and grounding to the box in inferior to having a separate ground wire home run to the service panel. I would strongly recommend running a new 4-wire copper cable to the breaker box. There was a FH article on this exact topic a few issue back -- check the FH index on their site. Spending a few hundred on this could save your house, and your lives.
*Let me give the disclaimer: I am not an electrician although I have played one around my house. I am, rather, a low voltage kind of guy, networks, telephones, computer wiring, etc.However, here at breaktime some of us never let knowledge or experience stand in the way of a response, so until a real electrician comes along, here is my take on your situation...Your previous oven was probably a straight 220 volt resistive unit that was unemcumbered by clocks, timers, etc, that required 120v. Two wires are all that is required for such straight 220 - the voltage across the two "hot" conductors coming into your house is 220 volts (or maybe 240, depending on the load on it). The neutral is actually a return leg, or grounded conductor, for a 120 v circuit. Since your new oven probably has need for 120 volts for all sorts of bells and whistles, you will need to run a neutral as well as a ground. You will need to read the NEC or get advice from an electrician on what is required for such a neutral, but it is my understanding that it needs to be run along with the "hot" conductors, it certain must be if it is run through conduit or is BX cable. Since you are going to have to run a neutral, I would agree with Andrew that you should just go ahead and run the proper copper wire from the panel.Aluminum still seems to be used for large conductors, particularly for service connections. I would not use it myself, but I have heard that in some areas it is about all that is available above a certain size. The NEC does allow for aluminum conductors but special precautions must be used. The NEC requires that the wire be connected together using special crimp devices, with an anti-oxidant grease properly applied. The tools and materials for the latter reportedly are quite expensive, so it is not practical to do it yourself unless you can borrow or rent the crimping tool.There is a lot of information on aluminum wiring on the Internet. For a brief descriptions of the problems and solutions see:http://homearts.com/pm/diybuzz/02probbe.htm"> Aluminum house wiring A more definitive treatment is given at:Aluminum Wiring in Residential Properties: Hazards & Remedies
*>However, here at breaktime some of us never let knowledge or experience stand in the way of a responseCasey,ROFLMAOThat should be in large type on the opening page right under "Fine Homebuilding"Rich Beckman
*Don, I think what the existing circuit doesn't have is an equipment grounding conductor. The neutral "served" as the ground and neutral (which is to say, there was really no equipment grounding conductor at all). This was Code-compliant until recently (the '96 Code as I recall).I agree with Andrew that you will be a lot safer if you have a separate neutral and equipment grounding conductors. One way is to run new cable. The other is to run a new EGC, which must be tied to the ground bar at the panel. It must follow essentially the same path as the current-carrying conductors, and be protected from physical damage. Also, it's no longer acceptable to run a ground to the closest water pipe...Aluminum conductors are just fine for applications like this. Do use the anti-ox paste, and make sure that the terminals are torqued to specifications. If you don't splice the conductors, then you won't need the compression splice tooling that Casey "heard of". (right-on Beckman).
*I should explain in part that I'm reacting in part to the electric stove service that some homeowner installed years ago in our house. Not good. Aluminum is fine with the larger screw-pressure connectors and paste, true -- doesn't almost everyone have aluminum service cables? -- but I'm wary enough of fire that I would avoid it if reasonably possible. I would also much much prefer a dedicated ground wire (4-wire cable, which he may have).We had scraps of aluminum wire throughout the house, some spliced between two copper runs (hard to find something like that! especially when the splice was stuffed into a wall cavity). The crimp device is made by AMP I think and is supposed to be electrician-installed; I've usually found running new wire to be easier and less expensive (but my labor is cheap).This sort of thing is a long way from wiring the occasional light switch, and even cheapo me might be willing to pry open the crusty checkbook for an electrician if I felt out-of-depth doing it. (We switched to gas instead.)I'll borrow from Taunton's disclaimer:>YOU USE THE SITE AND THE INFORMATION AND MATERIAL ON THE SITE AT YOUR OWN RISK. THE SITE PROVIDER SHALL NOT BE LIABLE FOR ANY DAMAGES ALLEGEDLY SUSTAINED ARISING OUT OF USE OF THE SITE, INCLUDING FOR VIRUSES [?] ALLEGED TO HAVE BEEN OBTAINED FROM THE SITE AND INCLUDING ANY CONSEQUENTIAL, SPECIAL OR SIMILAR DAMAGES, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*Was re-doing the 240 line for my dryer recently, and I noted that the old, original cable was braided. It was also silver colored, but it wasn't aluminum. Scratching it with a blade produced the copper color below the tinned coating. Not all old, silver colored wire is aluminum.
*Thanks-everyone has convinced me that I should just go ahead and run the proper 4 conductor copper wiring to the oven.
*I like the 'change to gas' idea!