I just inspected a 9 year old home. It was set up with Two 200 amp panels. The right panel is used as the main and the left panel as a aux/sub panel. They used a 100 amp breaker to feed the sub panel ,but they double tapped the neutral to the main incoming lug. The sub panel also retains the 200 amp breaker as it is a true (Main panel) I was told by an electrician that they should have used a pigtail/adapter on the main lug to make the connection instead of double tapping. What would be the correct way to wire these panels? ( The double tapped wire is the one with the white tape on it)See attached photos. Thanks, Ken
There usually a label with torque values inside the panel, it can have capacity ratings for lugs too.
These photos are small, and I have way too many questions for you to answer. Such as, clear tap on wires, bundling of jacketed cables, what is bonding the two panels, is the second panel box bonded, etc, etc, etc…
For those that think doubled up or ganged neutrals don’t matter. Found this yesterday on o 21 year old house. It was vacant so there was not any real load on the system. Notice the scorched and melted insulation on the neutrals. All the neutrals that were wired singularly these was not any scorching or melting. Looks like a poor connection to boot.
I just have to make a couple of comments.
Please do not take this as a defense of the improper practice of multiple neutrals.
A) I have seen dozens of melted and burned neutral connections like that. MOST, if not all, have been individual terminations.
The problem in that pic is NOT due to the “double taps” alone. It is due to a poor connection. Is that poor connection due to the double taps? I personally doubt it.
B) That bar is NOT discolored from heat. That is simply how they look after a while. It is absolutely normal.
Okay, I can buy that but then why are only those that were doubled or ganged discolored and melted while all the single connections pristene. I did go so far as to check it with a IR thermometer and it was room temp. I think some of the problems HI have with electricians is there is at minimum two camps regarding this kind of item. One camp says there is nothing wrong while the other camp says just the opposite. Meanwhile the NEC says do not do put more than one neutral under a lug. I too have seen ganged neutrals that were charred so I guess I am confused. What the hell is the right answer?
I can not tell you why some are pristine but those that are discolored is due to heat.
There will be no heat unless they are under load.
Those who say that there is no need to get all excited about doubled grounded conductor in panels installed prior to the adoption of the 2002 code are correct and well informed. Those who say that it has always been in the codes that doubled grounded conductors were not allowed are not informed.
I contacted UL and here is the response that I received, “UL 67 is a Certification Standard, not an installation standard.”
To be informed all one has to do is contact UL and ask.
Another way to be informed is to check the Report on Proposals for the code section that was changed to see what was used to substantiate the requested code change.
In the proposal that was made to mandate one neutral there was no mention of heated or damaged terminations. The ONLY thing that was mentioned was the unwanted affect of opening (turning off) of the other circuit.
For every charred conductor that you can show me where the conductors were doubled I can show you a charred conductor where only one conductor was under one screw.
The charring of the conductor comes from heat. This heat is produced by either being overloaded or a lose connection allowing arching. This charring does not magically come from two conductors under one screw.
Take a moment and step outside the reams of dwelling unit panels and step for a few minutes into the world of industrial machinery. Open up a control panel of an industrial machine or even some air conditioners, heat pumps, air handlers, cooking appliances and other such equipment in a dwelling unit and see the numerous conductors that are gained together in these appliances. I now ask what makes these gained terminations immune to the effects of the doubled grounded conductor.
Please understand that I am not saying to not call out the doubled neutrals for evaluation be a qualified electrician but I will openly make the statement if I am the electrician called I will check to ensure that the screw is tight, hand them a bill and go home if the house was wired prior to the adoption of the 2002 code cycle.
Do you have to regard the date that the house was constructed? What about the date the panel was installed? How about if the latest work inside the 10 year old panel included double neutrals? The age of the house is only a part of the data that I think of when inspecting an electrical panel.
I’ve come to understand that when a contractor renovates a kitchen, he/she has to bring everything with the electrical up to modern standards. Is that true for a qualified person doing work inside an electrical panel regardless of the panel age?