Prefab building grounding

[massfd]

We had a metal prefab building built (4000 sq ft) that is powered from a pole mounted service that already feeds a trailer pedistal and site lighting. The service has 2 driven rods and so does the pedistal.

The new building feeders (208v 3 phase Y 3 hots 1 neutral 1 ground) where run to the service pole and are protected by a 200A breaker. The entire job was just inspected and passed, the inspector was on site less than 5 minutes.

I feel that the building should have 2 ground rods (should have had a UFER but it's to late now), a bond to building steel and the water service bonded. Before I go to the engineer and look like a fool am I correct? The project documents just say "Grounding as per NEC".

The job looks perfect, all conduit run in a very workman like install with ECG for all circuits.

If I am correct can someone give me code sections to have the engineer review.

Please note this is not DIY, I am the maintenance supervisor. We do not do installs only service what is already installed. I just want to make sure my employer gets what is required

I do not know if anyone remembers my post a few years back about stray voltage on this site but we finaly got LIPA to repair their problems, some as far as 1/4 miles away and got the voltages under control. Used to be able to light a 12v lamp between the ECG on a site lighting pole and the chain link fence on the Rail Road property. Just do not want a repeat of the problem in this new building due to bad grounding.

 

[iwire]

250.32 requires this building to have a grounding electrode system.

 

[augie47]

Bob,
I don't disagree with you, but to play devil's advocate here, what makes this different from a mobile home that is fed the same way.
On most mobile homes we place a service pole, seemingly similar to what the OP has, up to 30 ft away and run a 4 wire feeder to the M.H.

With the Code definition of a structure, 250.32 can support your thoughts, but there seems to be some inconsistency.

 

[iwire]

I would expect a mobile home to have a GES as per 250.32. Is there an exception that for mobile homes that relives the 250.32 requirements?

 

[K8MHZ]

I would expect a mobile home to have a GES as per 250.32. Is there an exception that for mobile homes that relives the 250.32 requirements?

550.16 allows grounding through the cord. Some may feel that eliminates the need of an additional electrode system. I think the key word in there is 'adjacent'. How far away is adjacent?

How much difference would an additional pair of rods 30 feet from the rods at the pole mounted service make?

Ground rods are way overrated, anyway. Proper bonding is much more important. Our area is sand based and single rods only take the bond to earth connection down to around 1300 ohms. Fat chance of a second rod getting that anywhere near 25 ohms or so.

 

[petersonra]

I think it might need a bond to the steel frame. As a practical matter the conduit runs probably already bond it far better than you could do with another piece of wire.

If you have metal piping coming in it should be bonded too.

 

[iwire]

550.16 allows grounding through the cord. Some may feel that eliminates the need of an additional electrode system.

No argument from me, I have never done a mobile home.

I think the key word in there is 'adjacent'. How far away is adjacent?

How close is grouped? :grin:

How much difference would an additional pair of rods 30 feet from the rods at the pole mounted service make?

IMO not much.

Ground rods are way overrated, anyway.

Again no argument from me.

Proper bonding is much more important.

Without a doubt.


My personal feelings aside, 250.32(A) is pretty clear.

 

[massfd]

I agree with the comments

A ground rod or 2 does nothing to enhance grounding but can help with lightning.

The steel is most likely grounded by all the conduit and box atatchments but is a wire bond required.

The water service should be bonded and the meter jumpered.

Am I missing anything, just do not want to look stupid when I bring this up

 

[mcclary's electrical]

I agree with the comments

A ground rod or 2 does nothing to enhance grounding but can help with lightning.

The steel is most likely grounded by all the conduit and box atatchments but is a wire bond required.

The water service should be bonded and the meter jumpered.

Am I missing anything, just do not want to look stupid when I bring this up

Yes, it is required

 

[massfd]

Well they came back last week and did the following

installed 1 driven rod
ran a bond from the MDP to building steel
jumpered the water meter and bonded it to building steel

All jumpers look to be #6 or 8 bare copper run in PVC

I still think they need a wire run from the MDP to the water service, right now that connection is made thru the building steel.

What do you guys think

 

[RETRAINDAILY]

you can bond the water to building steel...?