On 3/12/2010 5:44 PM, Steven Trovato wrote:
> Peter,
> I don't think that is correct. My house has two outlet circuits wired
> with a single run of 14-3 Romex and a 220 breaker. Some outlets use
> one side of the 220, some use the other. But they all use the common
> neutral. This was reasonably common practice to save wire, and met
> the code, at least 25 years ago when my house was built. Besides,
> I don't think the loads add the way you say. In fact, because they
> are out of phase, they cancel out. This is why you try to balance the
> load between the two sides of the 220 at the panel. DISCLAIMER: I am
> not an electrician. I can speak with authority on how my house was
> wired, but I'm not an authority on the National Electric Code, or
> whatever codes apply to where you live.
I had a conversion on 220 and phase difference with a licensed
electrician some while ago and the topic of shared neutral came up. He
denounced the practice sharing a neutral. I understand the phase
difference cancelling and even asked him about it. He insisted it was a
bad practice, and IIRC said he had seen failures. Just thought I would
share the warning he gave me.
>
> -Steve Trovato
> strovato@optonline.net
>
> At 05:16 PM 3/12/2010, Peter J. Thomas wrote:
>> Do not use a common neutral. Each outlet needs is own common return.
>> If you use a 20A duplex break and 12 gauge 3 wire (4th wire bare
>> ground) romex (rated 20A IIRC) and install 20A outlets, the two hot
>> leads will be protected to 20A but a common return could be carrying
>> 40A if you plug in 2 20A loads, twice the rating for 12 gauge.
>>
>> Peter Thomas
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