Hi all. Today I was helping a Jman with a service upgrade. We set a J-box next to the new panel to splice all the old circuits in. When it came time to make up the connections the Jman said to run only one #12 from the neutral buss to the J-box for every two existing circuits. In other words one short piece of #12 was to be spliced to two neutrals so if there were 10 circuits we would only have 5 neutrals from the J-box to the buss. I asked if we should put the paired circuits on separate phases and he said no it didn't make any difference if they were on the same phase. Now I am confused. If the paired circuits are on the same phase wouldn't it be possible to overload the single wire when it tries to carry the unbalanced load of two 120 (L/N) circuits with a combined load over 20 amps? The J-man said it makes no difference because the neutrals all go to the same place. I'm not sure if he didn't really know what I was talking about or if I really don't know what I am talking about! He said it will pass inspection. Please help! If I am right I will not say it to him but I want to know for my own peace of mind. Also, could it pass inspection? thanks...Brian
As you stated, make sure that the shared neutral supplies circuits which are on two different phases or you will overload it. Since the JBox is so close to the panel, why not run a grounded conductor for each circuit to avoid any confusion?
Re: neutral bottleneck?#11037 06/26/0207:59 AM06/26/0207:59 AM
I agree with Urch. Certainly the cost of extending each grounded conductor into the new panel is negligible. Plus, in the event of a future alteration in the panel, there won't be a potential problem of one conductor trying to serve two circuits originating from the same leg.
Re: neutral bottleneck?#11038 06/26/0208:27 AM06/26/0208:27 AM
Brian, If you want to share a neutral, the ungrounded (hot) conductors must be on opposite phases. Someone needs to get a hold on this so called journeyman that you are working with! The situation that you are discribing is straight out of electric 101. When we did service up grades, we marked every conductor, and returned it to the phase that it belonged on. There were sometimes when we saw that someone else has moved some circuits around to phases that they should not have been on. In those cases, we would do some investigation, and take the steps needed to correct the problem.
Heck, Brian, send the guy to this forum. Maybe he'll learn something. I don't want to sound to harsh on the guy, but we're talking basic electricity and this guy is way out of line on it.
Cooling Down Now, Doc
The Watt Doctor Altura Cogen Channelview, TX
Re: neutral bottleneck?#11039 06/26/0211:24 AM06/26/0211:24 AM
Thanks guys for your input. Yes it's real hard to work under someone whose knowledge and ethics are questionable. Yes I will find a way for someone higher up to find out since I know it's the right thing to do even though I will feel like a snitch. Unfortunatley it seems there is not much pride of workmanship in a lot of trades today. That is why I am a firm believer in the old saying "If you want it done right, do it yourself".