Double Tap Main Line

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abernat

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Akron, OH
Apologize if this question is too vague or not meant for this type of forum.

I'm not trying to repair anything myself or instruct anyone as to how to fix this. I'm just looking for some advice and expertise and this seemed like the place to find it.

We are in the process of selling our home and the home inspection came back and said that the main line is double-tapped. I understand the general concept of what that means, but in reality have no idea what the "really" means.

That being the only information you have, and the attached picture... what would be the gambit of cost to repair such an issue?

Thanks for any guidance or info.
 

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"Double tap" means that you have two wires connected to the same lug. That may or may not be a problem. It depends on whether the particular panel was designed to accommodate the second connection. Another way to say that is that it depends on whether the panel's manufacturer "listed it" for that purpose (i.e., sent it to a testing lab to prove that it would satisfy all design requirements with the second wire connected). I would have to know the make and model number of the panel, to be able to check to see if it was listed for the double tap.

The reason for designing a panel to allow for a double tap is to allow one power source to feed two panels, without having to duplicate the wiring. You bring one set of wires to the first panel, then bring the second set of wires from the first panel to the second panel. If the two panels are close to each other but some distance from their power source, this can save you a lot of wire.

The photo you did include is not as clear as I could wish. It looks like there is only one black wire attached to the lug on the right, one black wire attached to the lug on the left, and one white wire attached to a lug in the center. As far as I know about such things, that should be all the wires coming into the panel. But I see two black wires connected to a lug to the left of the white wire. I can't tell from the photo what they connect to inside the panel, or where they go once they leave the panel. Do you, in fact, have a second panel somewhere else in the house? Could that second panel be getting power from the first one? If so, your installation might be code-compliant, or it might not. Much depends on the panel ratings, the wire sizes, and the overcurrent device upstream of the first panel.

My advice is to have an electrician look at the situation. You can't rely on a Home Inspector to know all the electrical installation codes. The best-case scenario is that the electrician might tell you the installation is good as-is. If that is not how things turn out, then that electrician would be in a better position to give you repair options and costs.

Please feel free to let us know what the electrician tells you. And let the electrician know that you have been communicating with us. The electrician would also be welcome to come to us for advice.
 
Let me add a plea: please do not put yourself or your family at risk by trying to investigate this situation yourself. There is a risk in the simple process of removing the front cover of a panel; something that might be loose inside the panel could break free from the vibration caused by taking the cover off. The risk of having the cover off for any length of time is even greater, as there are live high voltage components inside. I have heard it said that the 120 volts available in a household power system is too low to harm a human. Please do not believe that lie! The least funny and most poignant thing I have seen in a long time came from a sign that said, "Danger, High Voltage. Not only will this kill you, but it will also hurt all the time that you are dying."

Good luck, stay safe, and keep us posted.
 
Charlie it looks like the lug to the left of the white/neutral conductor is double tapped. Usually that smaller lug is a part of/connected to the neutral lug and the GEC is landed there. Possible two GECs; water pipe and rods would be common in resi.
 
The right side rear neural bar likely has positions that will accept one of those conductors - if they will reach there.

They do make add on lug kit for larger conductors that takes up a couple spaces on the regular neutral bar - can't recall the cat. no. off top of my head.
 
jumper said:
Charlie it looks like the lug to the left of the white/neutral conductor is double tapped. Usually that smaller lug is a part of/connected to the neutral lug and the GEC is landed there. Possible two GECs; water pipe and rods would be common in resi.
Click to expand...
You are probably right, in which case if it's not rated for two then all the electrician has to do it find another spot for one of them. Or they could be other neutrals. Should be marked.
 
GerryB said:
You are probably right, in which case if it's not rated for two then all the electrician has to do it find another spot for one of them. Or they could be other neutrals. Should be marked.
Click to expand...

Agreed. Strange that the installer wrapped the bare noodle in white tape, but did not mark the double tapped ones.

Noodles and EGCs have to be marked, but not GECs. Of course dorks like me will mark insulated GECs with tape.
 
Appears to be a Square D panel and the neutral is connected to the smaller lugs on the left.
Confusing which is one reason why I don't prefer Square D in the first place :cry:, but I suppose bare, white or green could be in there..what's more important is where they connect. If they are #6 or better they can be marked with white tape. I don't see any double taps from the photo.
 
newservice said:
Appears to be a Square D panel and the neutral is connected to the smaller lugs on the left.
Confusing which is one reason why I don't prefer Square D in the first place :cry:, but I suppose bare, white or green could be in there..what's more important is where they connect. If they are #6 or better they can be marked with white tape. I don't see any double taps from the photo.
Click to expand...

What is so confusing about Square D?

The two outer lugs are attached to the main breaker - those get the ungrounded supply conductors just like the lugs attached to the main breaker in any other panel.

The inner lugs are attached to the link between both grounded conductor bars. Many other panels have a link that connects each side grounded conductor bar as well. Many times the smaller lug is used for the grounding electrode conductor, but can be used for any conductor permitted to connect to the grounded conductor bus that is in the proper size range for that lug. If it is not a service panel or first disconnecting means of a separately derived system then all that can go there is grounded conductors, and equipment grounding conductors must go to a separate equipment grounding bar.

#6 must be white/gray or green/green with yellow stripe. You can only field mark grounded/grounding conductors that are #4 or larger.
 
If I lived close to you, I'd do it for $10.00 and Thank You,


JAP>
 
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