Are Temporary Protective Grounds ever used on systems under 600V?

[Calrissian45]

My organization works on low voltage systems (up to 600V) that include building electrical systems, PV systems, standby generators, and UPS. Is there any situation where we should consider using temporary protective grounds when working on these systems? My understanding is that they are only used for HV work, but I wanted to be sure that is the case.

 

[petersonra]

My organization works on low voltage systems (up to 600V) that include building electrical systems, PV systems, standby generators, and UPS. Is there any situation where we should consider using temporary protective grounds when working on these systems? My understanding is that they are only used for HV work, but I wanted to be sure that is the case.

I have heard of it being done on bus duct, but never actually seen it.

 

[mayanees]

NFPA 70E defines an electrically safe work condition (ESWC) as follows:
A state in which an electrical conductor or circuit part has been disconnected from energized parts, locked/tagged in accordance with established standards, tested to verify the absence of voltage, and, if necessary, temporarily grounded for personnel protection.
Maybe if the system is subject to inadvertent re-energization, or shift charge with different personnel working on it, then perhaps.
I see it done mostly on higher voltages for dissipation of charge.

 

[Red_Skull]

I believe one reason they are not used on low voltage systems is because the protective grounds would need to be able to handle the fault current if the equipment were energized with the grounds in place. A low voltage system will typically have a higher available fault current and would require much bigger grounds.

 

[Davebones]

We have 5 services into our plant . Transformers are 14.4kv to 480v . 2500kva to 1500kva in size . Any time we go into a main switchgear the utility pulls and grounds their primary stabs and they also then add protective grounds on the secondary feeding into our plant . The vendors working on our switchgear then verify absent of voltage and then add their own grounds at the main switch primary side coming in from the transformer ...

 

[kwired]

I believe one reason they are not used on low voltage systems is because the protective grounds would need to be able to handle the fault current if the equipment were energized with the grounds in place. A low voltage system will typically have a higher available fault current and would require much bigger grounds.

That really is going to depend on the size of system and/or any overcurrent protection that it will need to be able to carry sufficient current for interruption.

Low voltage systems more readily designed for lock attachments on just about any switch you might find on the distribution devices and there isn't much chance of any significant residual charges in most instances either.