Hi, I wondered if I can downsize the neutral conductor required for dryers and ranges. I'm running the wiring in RMC (aka thick wall metal conduit) which is acting as my equipment grounding conductor. I understand I have to run a neutral for these circuits because they use both 240V and 120V. This is for a new house.
--zeb
From what to what? Not that I would know the answer, but it certainly seems like an important part of a good question.
Although your own use of the word "required" makes me think you can't. Could it still be described as required if you could use a smaller one instead?
Yes, you can reduce the size of the neutral for a range not over
12kW. See NEC(2000) Section 210.19(A)(3) Exception No.2.The ampacity of the neutral conductor must be no less than 70% of the branch circuit rating. In all cases it can NOT be smaller than #10. A rule of thumb is that you can reduce the neutral one size.
While not required by NEC, if using metal conduit, good wiring practice calls for an equipment grounding conductor. It must be bonded to each metal junction box also.
Before installing ranges and dryers, always remove the terminal access cover in the back of the unit and make sure that the neutral/ equipment ground bond link is _removed_ for 4 wire circuits (new construction). In your case, if you don't pull an equipment ground, the RMC is the 4th wire.
For existing range/dryer circuits, where 3 wire circuits are permited, it is very important that the neutral/equipment bond link is _in_ place.
Most times when purchasing a new range/dryer one is given the option of a 3 wire (existing home) or 4 wire cord (new construction). Unfortunate- ly those cords are sometimes installed incorrectly by unqualified delivery people.
not having my code book home with me i cant readily get the code but i know here they do not allow downsizing of nuetrals anymore,but like most codes it comes down to what your local jurisdiction requires.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.