Return to the Electrical Wiring Forum | Post a Follow-Up

 o
Is this Main Panel Safe?

Posted by flyhop (My Page) on
Sat, Jun 29, 13 at 10:23

First off, I am a lifetime DIYer, but am not formally trained in much except teaching high school math. I can usually figure things out, but I do not mess around with electricity. Saying that, I am trying to avoid having to call a licensed electrician unless I know I have a problem.

We are in the midst of planning a series of renovations to our house, so I'm in the planning and demoliton phase. Funny how you tear into something, and it will lead you to bigger problems.

The one room I am focused on right now (all drywall gone) had 12awg old 2 wire without ground. Pulled all of the old stuff and wired up with NM 14awg (outlets only for the moment). This got me into the main panel so I could complete the run. Found this (see picture).

Bottom of panel is rusty. A number of the neutral/ground bus bar screws are rusty. Upon closer inspection, I found a few of the breaker's hot lugs/screws were also rusty.

Undaunted, I wanted to make sure I was tying into the right breaker. Put tester on breaker's hot post and on the box. Nothing. Moved tester to the neutral bus bar, and I get 125V.

1. Should I be concerned/alarmed that the main breaker box is not grounded? I think so.

2. System is grounded to cold water pipe. I want to ground it to...well...the ground. Reason? Moving to PEX so metal water pipes will be going away. Suggestions please on proper ground rod and bonding technique (awg suggestion also appreciated). Under house? Away from house?

3. Since the box has rust in the bottom (still solid metal under rust) and on some breaker's hot posts and neutral bus bar screws, is this thing safe?

Specs: ITE 200A Main Breaker. UL-Listed, but no date. Model G4040MG1200
Service: 4/0 AL (2 hot/1 neutral) from Meter.
Ground: to a cold water pipe (going to change that).

Would more pictures be helpful?

FWIW, there is a 30amp breaker from Main feeding a subpanel upstairs. PO did this when they turned attic into living space. Aside from a bathroom fan/heater/light, it's mostly all lights and outlets.

There is also a 60 amp breaker from Main feeding a subpanel just next to this Main Breaker. Same PO.

Lastly, there once WAS an above ground pool (same PO) fed by a 100 amp breaker on the main. This breaker is taped OFF, but I would like to move this to the garage for another subpanel, but I'll leave that for another post.


Follow-Up Postings:

 o
RE: Is this Main Panel Safe?

Forgot to mention that the meter has what appears to be #6 copper coming down to a grounding rod just below it.


 o
RE: Is this Main Panel Safe?

The rust is troublesome, but doesn't necessarily itself rise to a problem.

If you replaced 12 G with 14, make sure you are also not using more than a 15A breaker.

If the panel is NOT grounded, you have a massive problem. Are you sure it is really not grounded. If the panel is the main disconnect there isn't typically a seperate neutral and ground (in fact, it is required to be bonded together there if they are). That thing coming in from the meter is most likely also grounded to your ground rods. Are you SURE there is no ground coming into the panel other than the water pipe?

A metal water pipe coming in from underground needs to be connected to the (other) grounds regardless of what the interior piping is made out of.

If the interior piping is metal, it needs to be bonded to ground (this may also be served by the above ground connection).


 o
RE: Is this Main Panel Safe?

I've gone back and double-checked visually. Picture of lug holding copper ground is attached (lug is at the top of bus bar to the left of the main breaker). I used my hand and ran it the length of the ground, from outside the panel to the water pipe. No tie-ins, clamps or splices found.

I tried testing several breakers too. Putting one lead of simple 120V light tester to hot pole to any 15 or 20 amp breaker in this main panel and then touching the tester's other lead to the main panel/box does nothing. Moving the tester's lead from the panel/box to the neutral bar, tester lights up.

Only ground I can find (the one in the picture) goes to a water pipe.

So, am I looking at installing another ground rod (6+ feet away and running copper out to it?


 o
RE: Is this Main Panel Safe?

...but the metal box itself is not part of the grounding system. Isn't that...um...."bad"?


 o
RE: Is this Main Panel Safe?

I'm just spit-balling here, but with the sheer amount of bare copper grounds coming into this box....doesn't it kind of figure that surely ONE of them is touching this main breaker panel?

I'm going down to check out the subpanel next to it and chase down it's ground.

(think I know what I'm working on today....)


 o
RE: Is this Main Panel Safe?

ronnatalie....I've re-read your e-mail and realize we may be talking about two different things.

1. All the wiring in the house that has been replaced over the years has a hot/neutral and a ground. The neutral bar and the ground bar are connected at the base of the panel. Kind of forms a big "U" around the hot post which the 30+ breakers are hooked onto. Think the electrician took some measure of pride in his work as almost all of the neutrals are on one bus bar and all of the grounds are on the others. But, again, they are connected at the bottom (is that bonding?).

2. The large copper wire in the lug pictured in previous posting does go to the water metal pipe, but as the neutrals and grounds are bonded together, there is a neutral lugged from the service to the top of the other bus bar.

3. My initial post was expressing surprise that the metal breaker box itself was not grounded. The tester touching a hot post to the metal box. Shouldn't that complete a circuit?

Just making sure this thing is safe before I move on and ask other questions. Thanks for your input.


 o
RE: Is this Main Panel Safe?

Here's picture of upper 1/2 of panel. Left side: grounds.
Right side: neutrals.

Only ground leaving the box is lugged and terminates at water pipe.

But the box itself does not seem to be grounded as per light tester.


 o
RE: Is this Main Panel Safe?

OK, I misunderstood you. You mean the metal case itself doesn't appear to be grounded. That would be a problem. Typically the ground lugs are connected to the case internally. Are you sure you're touching some part that has the paint removed enough to make a good contact?


 o
RE: Is this Main Panel Safe?

ronnatalie....

I didn't know that paint was such an effective barrier to current. That was the ticket.

2nd lead to edge of panel box and got voltage.

Thanks.


 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!


Return to the Electrical Wiring Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.


Learn more about in-text links on this page here