Bonding strap needed?

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fkelly

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I recently inspected a large house with attached guest house. The service panel is on the exterior of the guest house. There are 2 branch panels next to each other in the house.
The guest house is attached to the house via roof and patio / slab.

I called out the ground / neutral bond straps in place in the branch panels and said they should be removed. Here is the response from the electrician:

"As for the removal of the ground neutral jumper bar a determination [was made] by the county inspector and myself during construction to treat the project as two separate structures. The installation is correct per the NEC with the grounds and neutrals tied together as well as a new ufer located at the subpanels and new gas and water bonds."

I still think this is incorrect. Any opinions?
 
fkelly said:
I recently inspected a large house with attached guest house. The service panel is on the exterior of the guest house. There are 2 branch panels next to each other in the house.
The guest house is attached to the house via roof and patio / slab.

I called out the ground / neutral bond straps in place in the branch panels and said they should be removed. Here is the response from the electrician:

"As for the removal of the ground neutral jumper bar a determination [was made] by the county inspector and myself during construction to treat the project as two separate structures. The installation is correct per the NEC with the grounds and neutrals tied together as well as a new ufer located at the subpanels and new gas and water bonds."

I still think this is incorrect. Any opinions?
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What code cycle are you under? If they ran a separate egc then you are correct the strap needs to be removed and the grounds and neutrals separated.

In 2008 NEC all separate structures would be treated as a sub panel in an attached building.

Now if it is a separate structure there needs to be ground rods driven and a main disco or not more than 6 handles to disconnect the structure.
 
Here is a photo, the panels are separately grounded from the service panel and no grounding conductor from the service panel. They use the IRC here so I guess the latest NEC applies.
View attachment 2901
Also, if the answer depends on the code cycle, I am thinking that either way is probably safe, I understand some of how this was changed around in 2008 as far as treating separate buildings, but do you have an opinion on which solution would be safer?
What was the logic in calling these separate buildings when they are on a connected foundation? It seems like there has to be multiple metal pathways.
 
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fkelly said:
Here is a photo, the panels are separately grounded from the service panel and no grounding conductor from the service panel. They use the IRC here so I guess the latest NEC applies.
View attachment 2901
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Hard to tell what you have but if it is the 2005 code then no EGC was necessary unless there is a metallic path between the buildings-- art. 250.32 of the 2005. In this case the neutral and grounds are bonded together along with the GEC.

In the 2008 this requirement has been changed and an egc must be installed. In this case the grounds and neutrals are separate and the GEC gets connected to the ground bar.

I do not see a main disco for this building either. If it is considered detached then that panel needs a main unless there is a disconnect on that building before this panel
 
Dennis Alwon said:
I do not see a main disco for this building either. If it is considered detached then that panel needs a main unless there is a disconnect on that building before this panel
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Excellent point, can't have it both ways.
Also, I would assume some metallic path, rebar in the slab, roof flashing, stucco lath, etc.
 
Can you give a better description of the "main service" on the exterior of the guest house. Where exactly do these subpanel feeders originate from, so sort of mdp?
 
I'm guessing that the main service located on the outside of the guest house has the OCPD's for the two subpanels. The guest house is attached so we have only one structure here. Since the feeders appear to be run in PVC, they should have pulled 4 wires and all the neutral/GEC connections should have been made at the main service on the outside. There is no need for the GEC to be landed in those sub panels nor should there be a neutral/EGC connection. I agree with the OP......
 
The service entrance panel has (2) 200 amp disconnects, one for one branch panel in the house and (1) for the also various breakers for the guest house plus a branch panel in the house.View attachment 2908
 
The equipment grounding conductors and the grounded conductors are tied together at the main mdp only.Once you leave there to go to a sub panel in the same structure they are seperated.Or if you leave there and go to a seperate structure you must bring an egc with the feeders and seperate them at the panel and have grounding electrodes or ufer at the seperate structure.

Is that use coming into that panel indoors?That is a no-no!
 
Yea.....It really makes it nice to be able to bring URD into a dwelling! Check your local supply house to see if they stock it. It is readily available in my area.
 
A/A Fuel GTX said:
Yea.....It really makes it nice to be able to bring URD into a dwelling! Check your local supply house to see if they stock it. It is readily available in my area.
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Is URD legal inside a dwelling. There are even restrictions on USE unless it is dual rated. Perhaps they make dual rated URD..

(B) Underground Service-Entrance Cable. Underground service-entrance cable (USE) shall not be used under the following conditions or in the following locations:
(1) For interior wiring
(2) For aboveground installations except where USE cable emerges from the ground and is terminated in an enclosure at an outdoor location and the cable is protected in accordance with 300.5(D)
 
Dennis Alwon said:
Is URD legal inside a dwelling
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Dennis.....This is directly from Southwire, " With the triple rated RHH/RHW/USE aluminum conductor, the aluminum is the required 8000 series aluminum and the insulation is flame retardant so it can be run in buildings. This product may be used as USE outside the building and as a RHH/RHW conductor inside the building.

This wire complies with NEC 310.14
 
A/A Fuel GTX said:
Dennis.....This is directly from Southwire, " With the triple rated RHH/RHW/USE aluminum conductor, the aluminum is the required 8000 series aluminum and the insulation is flame retardant so it can be run in buildings. This product may be used as USE outside the building and as a RHH/RHW conductor inside the building.

This wire complies with NEC 310.14
Click to expand...

Correct but my point is that not all urd is listed for indoor use. At least at one time that was true maybe they all are now.
 
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