Working Space around transformers

[brian john]

Re: Working Space around transformers

gregoryelectricinc:

The neutral XO wasn't grounded, you also had a short to ground on one of the phase conductors, seems to me.

We responded to a emergency call to a Circuit City store, The ground fault protected main switch was tripping on ground fault. During one such trip they loss $10,000.00. Power was out 5 minutes as they reset the main themselves.

 

[don_resqcapt19]

Re: Working Space around transformers

Bennie,
The ventilation openings at the top of the transformer are on the front and back on almost all transformers that I have installed. The installation instructions almost always specify a 6" rear clearance.
Don

 

[gregoryelectricinc]

Re: Working Space around transformers

Brian, There was no phase to ground short. The neutral was "floating" and since the GEC that should have been on XO was actually landed to the frame of transformer where the equipment ground should be, all of the metal parts were trying to "be" XO. Does this make sense?

 

[ron]

Re: Working Space around transformers

It would be hard (not imposible) to make a voltage or current measurement with the cover on. It is judgement, and you might as well consider the clearance required, especially if the Architect tries to reduce the size of the room. You would be hard pressed to answer to the client if you didn't have the clearance, and during construction the AHJ says it's required.
Size of infrastructure spaces are always a strugle with the "space programmers". The "space programmers" are generally Architects and need to get as much "productive" space as possible for the client.

 

[bennie]

Re: Working Space around transformers

Why is it "demanded" that a load or voltage test be made at the transformer?

No one has any business opening a tranformer while it is energized.

Read the OSHA regulations.

[ July 25, 2003, 08:33 PM: Message edited by: bennie ]

 

[websparky]

Re: Working Space around transformers

The original question was;

Does the working space in Article 110.26 apply to transformers? Would a 480V panelboard across the isle from a 480 to 208 transformer require 4' between them?

 

[bennie]

Re: Working Space around transformers

Condition 2, 42 inches.