Isolated equipment grounding conductor

[hhsting]

I have restaurant in which isolated equipment grounding conductor is used. However a separate conduit just for the IG conductor is provided to the receptacle. Separate branch circuit with equipment grounding conductor and circuit phase and neutral is provided for the same receptacle.

Would code allow to have IG in separate conduit from the branch circuit or not? Looked at 250.146(D) but got confused

 

[augie47]

Part of the wording in 250.146(D) seems clear: The receptacle grounding terminal shall be connected to an insulated equipment grounding conductor run with the circuit conductors.
Also:300.3(B) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors and bonding conductors shall be contained within the same raceway,

 

[infinity]

I agree with Augie It must be run with the circuit conductors. How are the normal EGC and the IG connected?

 

[LarryFine]

I agree with Augie It must be run with the circuit conductors. How are the normal EGC and the IG connected?

Same here, and hopefully they aren't. Someone misunderstood the meaning of 'isolated'.

 

[brantmacga]

Can’t say I’m surprised. I see a lot of bizarre installed when it comes to IG.

You may want to verify the IG ground bus is bonded. Can’t tell you how many I’ve seen connected to an independent grounding electrode.


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[curt swartz]

I though you were a plan checker? Are you seeing this installation in person or something on a set of plans?

 

[infinity]

Can’t say I’m surprised. I see a lot of bizarre installed when it comes to IG.

You may want to verify the IG ground bus is bonded. Can’t tell you how many I’ve seen connected to an independent grounding electrode.

How's this old one? IG connection for an IG bus in a panel. Safe to say that all of the IG receptacles weren't even grounded.

 

[JoeStillman]

Isolated grounds are just about the least understood thing in our industry. I consider them a solution in search of a problem. The IEEE tried to get people to call it an "Insulated Ground" in the Emerald Book, but it doesn't seem to have caught on.

 

[infinity]

Why is anyone still using IG systems in a restaurant? They are worthless and quite often not even designed or installed in a code compliant manner.

 

[jim dungar]

Why is anyone still using IG systems in a restaurant? They are worthless and quite often not even designed or installed in a code compliant manner.

Cut and place boiler plate specifications probably.
Aren't point of sale devices the same as they were 40 years ago?

 

[brantmacga]

Why is anyone still using IG systems in a restaurant? They are worthless and quite often not even designed or installed in a code compliant manner.

Most of the dozen or so quick serve brands I build use IG circuits. McDonald’s especially makes extensive use of IG circuits. Not sure if they’re still doing this at Chik Fil A because I quit building them, but they were running all their IG POS circuits through an isolation transformer.

Most of the POS vendors will not warranty their equipment unless it’s installed on an IG circuit. We have to sign an affidavit at the end of the job stating everything is to spec.

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[infinity]

Most of the dozen or so quick serve brands I build use IG circuits. McDonald’s especially makes extensive use of IG circuits. Not sure if they’re still doing this at Chik Fil A because I quit building them, but they were running all their IG POS circuits through an isolation transformer.

Most of the POS vendors will not warranty their equipment unless it’s installed on an IG circuit. We have to sign an affidavit at the end of the job stating everything is to spec.

We had a similar spec for POS equipment on a college cafeteria job. Needless to say we didn't install a single IG circuit and they never had a problem. Is there any proof that these IG systems are still actually needed or are the people paying for them getting ripped off?

 

[don_resqcapt19]

We had a similar spec for POS equipment on a college cafeteria job. Needless to say we didn't install a single IG circuit and they never had a problem. Is there any proof that these IG systems are still actually needed or are the people paying for them getting ripped off?

I recall reading that there are 3 outcomes from installing an IG system compared to a code compliant traditional system...things get better, things get worse, or things remain the same....in about equal proportions.

 

[infinity]

The way I've seen these system designed and installed over the years if a true IG system did have some benefit that was always defeated by poor installation and design. In the photo I posted in post #7 the installer ran a separate IG and EGC for every circuit in the panel and then chopped out some concrete and connected to a piece of rebar in the slab to make the isolated ground. I've also seen many installations where they just ran the IG to building steel. These systems could not have had much benefit over a standard wire type EGC.

 

[Dsg319]

https://www.ecmweb.com/content/article/20890911/the-basics-of-isolated-grounding-receptacles

 

[brantmacga]

We had a similar spec for POS equipment on a college cafeteria job. Needless to say we didn't install a single IG circuit and they never had a problem. Is there any proof that these IG systems are still actually needed or are the people paying for them getting ripped off?

I’ll say this…… I’ve remodeled a lot of older stores that have no IG at all, and use the same equipment as new stores with no issues. They still use the same IG4700 receptacle.

My personal opinion is that they’re being ripped off.


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[hillbilly1]

I always have to laugh when they truly “isolate” the ground. Insulated ground bar back at the panel, all the IG grounds ran to it, but no actual ground ran from it back to anywhere!

 

[LarryFine]

Aren't point of sale devices the same as they were 40 years ago?

Not really. Just about everything has an outboard "brick" power supply now.

 

[brantmacga]

To expand upon my earlier statement about being “ripped off”; the larger restaurant brands we work for have their own engineering teams that set the design specifications for the regional EE’s that design each project. The specification for IG’s comes from the POS vendors. I’ve never directly asked the brand engineers their thoughts on it, but without the vendor requirement, I doubt they would design that into the job. The POS vendors require every component in the system be connected to an IG circuit, which is usually 12-15 circuits per store, and about 50 IG receps.


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[curt swartz]

To expand upon my earlier statement about being “ripped off”; the larger restaurant brands we work for have their own engineering teams that set the design specifications for the regional EE’s that design each project. The specification for IG’s comes from the POS vendors. I’ve never directly asked the brand engineers their thoughts on it, but without the vendor requirement, I doubt they would design that into the job. The POS vendors require every component in the system be connected to an IG circuit, which is usually 12-15 circuits per store, and about 50 IG receps.


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Since you are heavily involved with building this type of restaurants I'm curious when the jobs are done and POS equipment is installed how much of it even connects directly to the receptacles?

Most of the equipment I see in other retail businesses gets powered from wall warts/power bricks, USB or PoE. I looked online at some restaurant POS systems and found the same. Much of it is PoE to allow simple installation, data and power with 1 cable.

Basically most of the equipment out there doesn't connect to the EGC.