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Old 10-25-2017, 08:40 PM   #46
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Re: $13 Ground Headache


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Originally Posted by Fishbulb28 View Post
At that time it was perfectly acceptable to run a 3 wire feeder (no equipment grounding conductor) to a remote building or structure. The feeder is then treated almost exactly like a service. The structure's grounding electrode conductor connects to the feeder neutral, a bonding jumper connects the feeder neutral to the structure's equipment grounding conductors.
Thank you! This is certainly good news as the cost will come down significantly for a repair.



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Originally Posted by Fishbulb28 View Post
Right idea, wrong location. The bonding jumper needs to be in the same enclosure as the building's disconnect. In your case, the home's electrical panel.
So in this case the bonding would occur in the subpanel? Is this still safe or would I be better running an entire new single cable for a ground from the subpanel to the main panel?

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Originally Posted by Fishbulb28 View Post
Normally this would be done with a bonding screw but it's unlikely you'll ever find the approved Bryant screw. A wire jumper is fine, but the size of the feeder conductors is needed to determine the size of this jumper. I can't read anything on them in the photos.
I can't find anything talking about a bonding screw on the panel. I'll do some more looking though.

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Originally Posted by Fishbulb28 View Post
This is actually your only expensive problem. Flexible cord can't be used here. It needs to be replaced with an appropriate cable or conduit and individual conductors but you were thinking of doing this anyway.

The three conductor feeder was code compliant up until recently, 2005 or 2008. That part of your installation is still grandfathered in even under current rules. The flexible cord was never compliant.
I found it was ITT 6/4 SO cord so that needs to be replaced with something more like the service al cable? I can find mobile home feeder wire in 2-2-2-4.

Reading about grounding and bonding though wouldn't having the jumper in the subpanel create a fairly unsafe flow if a problem occurs?

At least I know now what the problem is and don't have to pay for a "it don't work right, fix it" type of problem.

I'll see what everyone thinks about the mystery box now and see if I need a pro or just a trench with a ground wire to the main panel.
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Old 10-25-2017, 08:42 PM   #47
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Re: $13 Ground Headache


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Originally Posted by joed View Post
TADA open ground. I will leave it to USA experts to say what the proper solution might be.
Yeah, I guess I win for guessing the cable wouldn't be connected to anything. Is that winning??? Gotta give my little tester some props though for finding it. Thanks for all your help!
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Old 11-10-2017, 02:39 AM   #48
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Re: $13 Ground Headache


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So in this case the bonding would occur in the subpanel? Is this still safe or would I be better running an entire new single cable for a ground from the subpanel to the main panel?
Correct, the bond between the feeder's grounded conductor and the home's equipment grounding conductors will be at the home's panel.

This is safe as long as there are no grounded connections between the garage and the home. No metal water pipes, cable TV, intercom, nothing that would create a path between the ground systems of the home and garage. Having any of those paths, or planning to install something which creates one, would be the only reason to need the fourth conductor on the home's feeder.

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I can't find anything talking about a bonding screw on the panel. I'll do some more looking though.
A length of #8 copper conductor between the two bus bars will work just as well.

If you locate and use a bonding screw you must also move the grounding electrode conductor over to the neutral bus. If you use the wire jumper you may leave it where it is.

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I found it was ITT 6/4 SO cord so that needs to be replaced with something more like the service al cable? I can find mobile home feeder wire in 2-2-2-4.
Flexible cord can't be used in this situation and what you have is dreadfully undersized. What size is your service? If it's greater than 100A then you will need #1 aluminum. If it's 100A then #2 is fine.

MHF will need to be placed in conduit between the junction box and the cable entrance to the home. Usually there is already metallic conduit leading from the panel to underneath the home. Is that what you have? The equipment grounding conductor in the MHF cable isn't needed so it's just wasted money, but MHF is so cheap and this is such a short run you won't notice. You can also use something like SER cable if it's easier for you.

Can't say for sure, but it looks like the splice is done with split bolts. Are you familiar with making connections using them?

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Reading about grounding and bonding though wouldn't having the jumper in the subpanel create a fairly unsafe flow if a problem occurs?
No. You're re-creating the same type of main bonding jumper that is in the service panel. What you have now is dangerous. A ground fault cannot trip any overcurrent device and will leave every conductive grounded object in the home electrified.
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Old 11-10-2017, 02:59 AM   #49
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Re: $13 Ground Headache


I just looked at the home's panel photos again and wanted to ask one more thing. What size is the conduit to the panel for the feeder/service entrance conductors? It looks a little small to use aluminum so you may need to use copper when replacing the section of flex cord.
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Old 11-13-2017, 05:09 PM   #50
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Re: $13 Ground Headache


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Originally Posted by Fishbulb28 View Post
I just looked at the home's panel photos again and wanted to ask one more thing. What size is the conduit to the panel for the feeder/service entrance conductors? It looks a little small to use aluminum so you may need to use copper when replacing the section of flex cord.
Thanks Fishbulb, the small feeder piece going to the home panel is 1 1/2" od. For that piece I'm hoping to find a copper piece anyway.
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