DIYbanter - View Single Post - neutral downsizing for dryer and range --where in the NEC?

volts500

wrote:
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.

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.