3-Pole transfer switch without a EGC

[Tyaus]

I have a question I hope someone can answer, I am currently in Iraq working as a electrician and I have run across this situation a couple of times. There will be 2 generators feeding a 3-pole transfer switch with no EGC ran with the cables, just 3 hots and a neutral. The generators are both bonded and the transfer switch frame is then bonded to the neutral at the switch. There is no other metal parts connecting the gens and transfer switch which would create a parallel path. My question is this okay per the NEC.

Thanks,

 

[infinity]

What kind of raceway is being used?

Welcome to the Forum.

 

[bob]

There will be 2 generators feeding a 3-pole transfer switch with no EGC ran with the cables, just 3 hots and a neutral. The generators are both bonded and the transfer switch frame is then bonded to the neutral at the switch. There is no other metal parts connecting the gens and transfer switch which would create a parallel path. My question is this okay per the NEC.

Thanks,

Just to make the situation clear, is this the main service to the building or do you have another main service to the building with the generators being an emergency service?

 

[erickench]

If the raceway is metal you will have objectionable current. NEC 250.118 classifies metal raceway as being an equipment ground. Are the generators bonded to any metal enclosure with a system bonding jumper? Are the raceways fastened to this enclosure?

 

[Smart $]

Need more info for definitive answer... but basically it is ok per NEC.

Not required but I'd install and bond a ground rod at each gennie.

The required grouding electrode system must be bonded to neutral at the xfer switch (assuming it is service entrance rated, and serves as the disconnecting means).

I'd cite reference(s) but there is no section which requires a grounding conductor between gensets and xfer switch.

 

[mcclary's electrical]

Need more info for definitive answer... but basically it is ok per NEC.

Not required but I'd install and bond a ground rod at each gennie.

The required grouding electrode system must be bonded to neutral at the xfer switch (assuming it is service entrance rated, and serves as the disconnecting means).

I'd cite reference(s) but there is no section which requires a grounding conductor between gensets and xfer switch.

Don't forget you're talking about driving a rod in sand here:roll:

 

[Tyaus]

Thanks for all the help, we run into alot of stuff over here that you dont see back home. The cables they use we call 4-core, it is 4 conductors with heavy rubber insulation around them. There is no metal besides the conductors in the cables. There is a ground rod at each gen and also at the transfer switch which then feeds a MDP about 50 meters away. All of this equipment is out in the open, they usually do a gen switch every 3 days so 1 gen doesnt get worn out. There also is a cable that is a 4-core with armour strands around it that serves to protect the conductors and as a ground, but in this case it was the unarmoured cable. Almost all the transfer switches here are just to switch from one generator to another.

Thanks once again.

 

[benaround]

Need more info for definitive answer... but basically it is ok per NEC.

Not required but I'd install and bond a ground rod at each gennie.

The required grouding electrode system must be bonded to neutral at the xfer switch (assuming it is service entrance rated, and serves as the disconnecting means).

I'd cite reference(s) but there is no section which requires a grounding conductor between gensets and xfer switch.

I have to disagree with this, these are not service conductors, they are feeders. Feeders

require an EGC run with the phase and neutral conductors.

 

[Smart $]

I have to disagree with this, these are not service conductors, they are feeders. Feeders

require an EGC run with the phase and neutral conductors.

I'll entertain your disagreement if you can cite reference(s).

I understand what you say is the typical mode of thinking, and the NEC leads one to believe such... but does it really say that. Perhaps I'm blinded, so please enlighten me. To start, I'll agree the non-current carrying metal parts of the generator are required to be bonded... but you'll have to hold my hand and show me where bonding via the grounded conductor is not permitted. Also, remember this is an instance, though not totally confirmed, where OCP of the generator does not serve as the disconnecting means.