DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (http://www.diychatroom.com/)
-   Electrical (http://www.diychatroom.com/f18/)
-   -   neutral size question (http://www.diychatroom.com/f18/neutral-size-question-35791/)

tommy potatoes 01-13-2009 07:59 AM

neutral size question
 
I'm replacing my oven, which had 30 amp service, with a slightly larger one that requires 40 amp service (all 240 vac).

My original service was 240 vac single phase, using 2 10 awg stranded with a 12 awg neutral, in 1/2 inch emt conduit.

According to a NEC table I looked at, I can pull up to 3 8 awg thhn wires in 1/2, which looks like a full plate to me. Can I use the same rule of thumb as the original installer, and use two 8 awg conducters with a 10 awg neutral, as I already have an all metal conduit ground path?

InPhase277 01-13-2009 09:00 AM

Quote:

Originally Posted by tommy potatoes (Post 211885)
I'm replacing my oven, which had 30 amp service, with a slightly larger one that requires 40 amp service (all 240 vac).

My original service was 240 vac single phase, using 2 10 awg stranded with a 12 awg neutral, in 1/2 inch emt conduit.

According to a NEC table I looked at, I can pull up to 3 8 awg thhn wires in 1/2, which looks like a full plate to me. Can I use the same rule of thumb as the original installer, and use two 8 awg conducters with a 10 awg neutral, as I already have an all metal conduit ground path?

If its 240, why do you need a neutral?

AllanJ 01-13-2009 09:51 AM

Quote:

Originally Posted by InPhase277 (Post 211902)
If its 240, why do you need a neutral?

A 240 volt only branch circuit does not need a neutral. If 120 volt usage is also intended then you need a neutral; the ground does not suffice. A 240 volt (stove) receptacle that has a neutral contact must be fed with a 120/240 volt circuit (with neutral). Most electric stoves also require 120 volts including for clocks, timers, etc.

jerryh3 01-13-2009 10:15 AM

Quote:

Originally Posted by AllanJ (Post 211916)
A 240 volt only branch circuit does not need a neutral. If 120 volt usage is also intended then you need a neutral; the ground does not suffice. A 240 volt (stove) receptacle that has a neutral contact must be fed with a 120/240 volt circuit (with neutral). Most electric stoves also require 120 volts including for clocks, timers, etc.

I think he knows that. He's asking the OP why he needs a neutral if he states the oven is 240V load.

tommy potatoes 01-13-2009 10:25 AM

My old oven had the neutral hooked up, and the installation instructions for the new one call for it, too.. And yes, everything with electronic displays most likely utilizes the neutral to provide 120vac service to the LVPS.. I understand that much.. So, since the neutral is not called in to play for more than 120V mains for a LVPS, I guess 10 awg is plenty, eh?


All times are GMT -5. The time now is 06:02 AM.