Clearances to Tranformer

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tiffytommy

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I have a pad mounted, enclosed transformer 46" away from a masonry wall. I would like to install a window in that masonry wall. I am not having any luck finding clearances for this in the NEC.

Any help would be greatly appreciated.

Thank You.
 
Re: Clearances to Tranformer

Is this transformer in a vault by any chance? If so, you will have to install a fire rated window. If it is not in a vault, I don't know of any restrictions.
 
Re: Clearances to Tranformer

This is a design issue covered by building codes (not the NEC) and insurance company requirements.

Some items to consider are the amount of liquid in the transformer (usually done by KVA rating), the type of liquid (padmounts are usually oil filled) and the ground conditions around the transformer (i.e. fire quenching ability).
 
Re: Clearances to Tranformer

I allow 6" space behind transformer if smaller, if larger (like 1000kVA) then 12" for ventilation purposes. Front of transformer I treat like regular equipment (3, 3.5 or 4')depending of situation.
 
Re: Clearances to Tranformer

There is nothing in the NEC that says you can not install a transformer below a window. Never hurts to call the counter and talk to the local AHJ at the building department though.

However, If I was a Fire Inspector I might have cause to be unhappy due to emergency egress restrictions should I have to go out/in the window during a fire.

Technically, a window is only a window if it opens. Otherwise it is a glass wall. So a screwed shut window may be satisfactory for inspection purposes.
 
Re: Clearances to Tranformer

The clearance requirements are generally dictated by the local utility. They normally try and conform to the National Electrical Safety Code which is published by IEEE. You need to contact your local utility for specifics.
 
Re: Clearances to Tranformer

The clearance requirements are generally dictated by the local utility. They normally try and conform to the National Electrical Safety Code which is published by IEEE. You need to contact your local utility for specifics.
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I agree 100%. In fact, we will bill the customer for moving the transformer if he impinges on our transformer space by installing a window. :D
 
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