Our house has a 200 A main panel. It's a General Electric panel that was installed in 1989, when the house was built.

I am in the process of installing a 120/240 V, 50 A receptacle in the basement. Today I ran the 6/3 wire to the main panel shown below.



I then noticed a problem... the neutral/ground bus bar inside the panel is full.





There are some small, unused slots in the neutral/ground bus bar I can use for my ground wire. But no unused lugs for my big 6 AWG neutral wire. (The existing neutral/ground bus bar only has two large lugs, and both are used.)

What should I do? Can I install a second neutral/ground bus bar in the panel? If so, how – exactly – do I do this to code? What AWG wire is required between the existing neutral/ground bus bar and the second neutral/ground bus bar? Can the second neutral/ground bus bar be screwed directly to the panel (to the right of the main circuit breaker)? Or must it be electrically isolated from the panel?

 

To anyone that reply's to this post please notice what looks like a burned ground at the main, and what looks like a burned neutral on the buss.

 

I think the discoloration is from a grease. I see it in a lot of older panels.

A ground bar can be added to the enclosure and grounding conductors can be moved to make room for neutrals on the existing bar. A #4 should fit in those holes so a #6 should have no issues.

That panel looks like it has more neutrals than circuits. It might be worth a look to see if they are all in use. Is the bottom bar empty closest to the main breaker?

 

The panel wiring to the sub should have been identified with white on both ends. There may be more issues also.

 

Thanks for the feedback.

Yea, that's grease on the aluminum neutral conductor coming from the meter.

I never thought that a #6 would be able to fit into one of the small lugs in the existing neutral/ground bus bar. I'll check it out.

Oh, and I'm the one who installed the sub panel. I wasn't aware that there's supposed to be white tape on the neutral. I will correct this. Thanks.

 

Am I'm not sure why there are so many neutrals. Will look into this, too.

While I'm at it... what's the rule on "doubling up"? Am I allowed to have two ground wires in the same slot? Am I allowed to have two neutral wires in the same slot? Can I have a neutral wire and ground wire in the same slot?

 

Neutrals are one per hole. Grounds can typically be doubled in certain size combinations. Check the panel label.

In the old panel the larger white and green should not be sharing the lug.

 

Looked at it a little more. Some of the holes in the existing neutral/ground bus bar are small, and some are large. The panel says the large holes can accommodate #6 stranded.

The existing neutral/ground bus bar is a bit of a mess... I can see a couple instances where there's a single #12 ground wire in some of the large holes.

So this afternoon - while the wife and kids are out shopping - I'm going to shut off the main breaker, remove all the neutrals and grounds from the existing neutral/ground bus bar, and re-do it.

And if I understand correctly...

1) One slot can accommodate multiple grounds.

2) Each neutral has to be in its own slot (i.e. it is against code for two neutrals to share the same slot, and against code for a neutral and ground to share the same slot).

Is that correct?

 

One neutral only per hole, correct.

 

Almost always two grounds of the same size are allowed and sometimes three may be allowed, check the panel label.