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New oven wiring: 3 wire or 4 wire

GeenH's picture

I am having an addition done to my house for a new kitchen. The person installing the wiring used a 3 cable wire for the free standing oven. From what I understand the electrical code now requires a 4 wire cable for an oven. For what reason did the code change to a 4 wire?


Thanks

(post #109799, reply #1 of 4)

3 wires are 2 hot legs, one common leg.


4 wires are 2 hot legs, one common leg, one ground leg or connection.


All the recepticals are labeled accordingly and there should be a bare copper wire (not white) that provides the grounding.


220v is something that is potentially fatal so if you aren't familiar you ought to consider calling an electrician. There are different amperage plugs as well so it isn't as simple as I make it here. There are NEMA specs for the plug size & pin configuration based on the amperage. The breaker at the load center should also match your range amperage.


Starting at the range figure out which amp draw is necessary. 30, 40, 50 Amps are all possibilities.


Next check the breaker handle. In the load center there is a pair of breakers tied together at the handle and there will be a Amp rating on it.


If the breaker is smaller than the amp draw at the range you have an issue to deal with. The issue is that the electrician put a breaker in to protect the wire. If he put in a 30 amp breaker then the wire is able to supply that much power. HOWEVER if the range requires 40 or 50 amps, then you can't just change the breaker and put in a new receptical, you need to have the wire replaced to allow for more current to flow to the range.


Simply put the Plug has to match the Range amp draw, the wire has to match or exceed the breaker 's limitation on amperage.


If you are getting lost it's best to call someone to walk you thru it. Don't let luck figure into it.

Jack of all trades and master of none - you got a problem with that?

(post #109799, reply #2 of 4)

Booch had an excellant response. Unfortunately it does not have much to do with your question. <G>

First I will answer this with a generic ranges and dryers.

Those operate on both 240 and 120 volts. Thus they require the 2 hots and a neutral. Pre 1996 code did not require a separate ground connection in most cases. To supply the "ground" they allowed the metal chassis to be connected to the neutral. On the equipment there would be a jumper, or strap of some kind that ties the ground to the neutral and then 3 wires connections to the pannel.

The problem with system is if anything happens with the neutral connection then the case will become hot.

The new code requires 4 wires with a separate ground wire. That keeps the case as ground even if there is failure in the neutral wire.

But you indicated that this was an oven. It is possible that the oven only requires 240 volts. Check the nameplate and the installation instructions. If that is the case then it it does not need a neutral. So a different set of 3 wires can be used. 2 hots and a ground.

. William the Geezer, the sequel to Billy the Kid - Shoe

(post #109799, reply #3 of 4)

Thanks for the information. The range I ordered, but don't have delivered yet, does use standard incandescent bulbs so 120volts is used. The range is a Kenmore. The on-line specs for this model don't stipulate the number of wires needed for the hookup. Since they offer both a 3 and 4 wire cord to plug the thing in, it appears it could go either way.


Sounds like I should have a 4 wire put in.


 


 

(post #109799, reply #4 of 4)

Since they offer both a 3 and 4 wire cord to plug the thing in, it appears it could go either way.


They offer both fopr older houses which have the older wiring.  New model codes generally require 4 in your situation, but your local code authority has the final say as to which applies.


 


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