This is not how you do isolated ground ....

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brantmacga

brantmacga

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I've seen this at least a dozen times now.

This is a restaurant we're gutting and remodeling. Many years ago this particular brand starting requiring IG for all POS equipment, and they required existing stores to have new panels put in for the IG receps.

This is one such install.

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IG grounding conductor goes straight to a ground rod. We're going to take both the Eaton and Siemens panels out, add a new NQ panelboard for equipment and a QO loadcenter for the IG.


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"Isolated" and "ground" seem oxymoronic to me. There is only one ground.
 
ggunn said:
"Isolated" and "ground" seem oxymoronic to me. There is only one ground.
Click to expand...

This particular brand is hardcore about having the IG on POS equipment. We always have to sign an affidavit at the end of the job to say it's correct and to their specs. We'll end up with about 50 receps total in 4000 sq ft of restaurant.

Most others have moved away from it, as it is really no longer needed with modern equipment. A couple of other restaurant brands we build also require it, but not to the level of the store pictured above.


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brantmacga said:
This particular brand is hardcore about having the IG on POS equipment. We always have to sign an affidavit at the end of the job to say it's correct and to their specs. We'll end up with about 50 receps total in 4000 sq ft of restaurant.

Most others have moved away from it, as it is really no longer needed with modern equipment. A couple of other restaurant brands we build also require it, but not to the level of the store pictured above.


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Click to expand...

wow. failed to grasp the concept, eh?

the reason you want an isolated ground back to
the MAIN ground bus is to prevent ground loops,
that might bias solid state devices and cause madness.

but grounding all the devices to a point completely
different than the service ground virtually guarantees
a ground loop.

you can't fix stupid.
 
Fulthrotl said:
wow. failed to grasp the concept, eh?

the reason you want an isolated ground back to
the MAIN ground bus is to prevent ground loops,
that might bias solid state devices and cause madness.

but grounding all the devices to a point completely
different than the service ground virtually guarantees
a ground loop.

you can't fix stupid.
Click to expand...

Personally, I'd be more concerned about not having a proper ground fault current path and the potential for someone to get shocked, then I would be about ground loops.
 
Cow said:
Personally, I'd be more concerned about not having a proper ground fault current path and the potential for someone to get shocked, then I would be about ground loops.
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I agree, it might be marginally better than this gem that I found in a Post office. Guess that they couldn't get to the earth from the third floor.

Isolated Ground connection.jpg
 
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infinity said:
I agree, it might be marginally better than this gem that I found in a Post office. Guess that they could get to the earth from the third floor.
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Haven't you ever seen an ECEE (Elevated Concrete Encased Electrode) before. It is also referred in the trade as a Whatfer instead of a Ufer.
 
Cow said:
Personally, I'd be more concerned about not having a proper ground fault current path and the potential for someone to get shocked, then I would be about ground loops.
Click to expand...

Yeh, that was my explanation to the owner. At that point, cost didn't matter.


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infinity said:
I only wonder why in 2017 people are still specifying IG systems. :slaphead:
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I'm not kidding when I say this is priority number 1 on the electrical installation for these guys. Along with the affidavit, we have to send pictures of ORANGE IG receps to the POS vendor before they will come out to install.

My supplier ran out of orange receps once, and I used ivory IG receps with the orange IG symbol in the corner. It turned into a crap storm.


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infinity said:
I agree, it might be marginally better than this gem that I found in a Post office. Guess that they couldn't get to the earth from the third floor.

View attachment 18208
Click to expand...

I see the problem; fitting instead of a bushing on the EMT... wait, no, they didnt use a rebar to EMT fitting... clamp not listed for use on rebar (ECEE LOL)... I think I'm close... aha, I have it: they used a red wire for ground! That's it! everyone knows you only use red wires on bombs when there is a 50/50 chance of cutting the wrong one with less than two seconds on the timer!! :D
 
brantmacga said:
I'm not kidding when I say this is priority number 1 on the electrical installation for these guys. Along with the affidavit, we have to send pictures of ORANGE IG receps to the POS vendor before they will come out to install.

My supplier ran out of orange receps once, and I used ivory IG receps with the orange IG symbol in the corner. It turned into a crap storm.
Click to expand...

This demonstrates the sheer stupidity of people. You require an orange IG receptacle but do not even know enough to check and see if it's actually properly grounded. :slaphead:
 
I have seen isolated ground requested tons of times. At lease half the time when questioned further, the "specifier" is only envisioning a dedicated ground wire to the nearest panel. I love it when an Electrical Engineer specifies isolated ground and then doesn't provide any isolated ground busses or an additional wire in any of the conduits. I hate it when I have to bid one, because I understand the requirements and I assume there is usually going to be one idiot who doesn't. There was a thread here yesterday that someone was asking about whether to bid to code or spec. Here is one that I will usually just clearly state in my proposal, "Excludes additional wiring or components are required for isolated ground that are not shown on the plans." I will usually highlight it.
 
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