Transformers and unit substations. - Electrician Talk - Professional Electrical Contractors Forum

MDShunk · 01-28-2007, 11:52 AM

These pictures show the interiors of customer owned transformers from recent and ongoing work. The larger transformer is about 8 feet tall.

Special thanks to Derek Pasch, Staffing Specialist at Meisner Electric in Delray Beach, FL for the pictures. There might be a small problem with the bottom installation. Do you see what I'm seeing?

DeepOne · 02-06-2007, 04:52 PM

Hmm.. mouse may penetrate a box through upper slot?

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MDShunk · 02-06-2007, 06:13 PM

Quote:

Originally Posted by DeepOne

Hmm.. mouse may penetrate a box through upper slot?

.

That's very true, but that mouse won't last very long. Neither will a snake.

Joe Momma · 02-06-2007, 06:33 PM

I don't see a problem with the bottom install.

I don't see a GEC, but that may be the angle.

We don't use flex for transformers(or much at all), usually hard pipe or gutters. But they did use ground bushings so it all looks okay to me.

What kVA are those big suckers?

Joe Momma · 02-06-2007, 06:35 PM

Oh, your talking about how they used the rigid coupling aren't you?

JohnJ0906 · 02-06-2007, 06:49 PM

Looks like a GEC (at least it looks green) Exiting conduit at the bottom of the panel. I cant see where it goes after the bonding bushing at the transformer, though.

Joe Momma · 02-06-2007, 07:07 PM

Quote:

Originally Posted by JohnJ0906

Looks like a GEC (at least it looks green) Exiting conduit at the bottom of the panel. I cant see where it goes after the bonding bushing at the transformer, though.

That would be commonly known as an EGC, because it's the conductor grounding the equipment.

JohnJ0906 · 02-06-2007, 07:19 PM

Got my abreviations confused on that one!

John · 02-06-2007, 08:35 PM

It looks like it might get a little hot in the there!
NEC 450.9

MDShunk · 02-07-2007, 05:04 PM

Quote:

Originally Posted by Joe Momma

Oh, your talking about how they used the rigid coupling aren't you?

No, I was talking about the apparent lack of working space (width) in front of the panel.

JohnJ0906 · 02-07-2007, 07:39 PM

Quote:

Originally Posted by MDShunk

No, I was talking about the apparent lack of working space (width) in front of the panel.

Kind of hard to tell from the angle the picture was taken. It might be 30", but it does look less.

HCECalaska · 04-15-2007, 11:27 AM

what about only one wire on X0 should be a ground bond there.

buck · 04-15-2007, 12:20 PM

Quote:

Originally Posted by John

It looks like it might get a little hot in the there!
NEC 450.9

Would a room this small need an exhaust fan above the transformer?

brian john · 04-15-2007, 06:37 PM

Joe;

While it is not code, here if one were to use conduit or a gutter, everyone and his brother would have a fit and the inspector would most likely turn it down. Till you prove to him it was legal per the NEC.

Different areas, different practices.

Joe Momma · 04-15-2007, 10:53 PM

Quote:

Originally Posted by brian john

Joe;

While it is not code, here if one were to use conduit or a gutter, everyone and his brother would have a fit and the inspector would most likely turn it down. Till you prove to him it was legal per the NEC.

Different areas, different practices.

You'll have to explain what you're talking about Brian because I haven't the slightest clue from your post.

brian john · 04-16-2007, 02:51 AM

Joe: Sorry for the confusion:

Quote:

You'll have to explain what you're talking about Brian because I haven't the slightest clue from your post.

In Washington DC, every transformer installation utilizes flex, even though this is not a requirement of the NEC. The few jobs where contractors installed EMT straight to the transformer have been ridiculed by other contractors and inspectors I have asked inspectors about this issue and they say (or believe) this is an NEC violation. Why we do this here and everyone has such strong feeling about this issue I DO NOT KNOW. In other parts of the country this practice is not followed.

Joe Momma · 04-16-2007, 08:42 PM

I've seen transformers flexed around here, but have never flexed one.

I can't remember anything in 450 saying Pipe is no permitted.

We always frown on flex around here, it does have its uses(equipment that moves, but mainly for saving time) but looks bad and says the installer is not very good with pipe.

brian john · 04-16-2007, 08:59 PM

Joe:

The issue here is not the installers ability to install pipe, even on jobs where the installers are the best pipe men around Flex is still utilized. My point was I am not sure why it is so instilled in the installation practices in this area. Inspectors and installers.

faber307 · 04-16-2007, 10:12 PM

Everywhere I've worked here in MI, We flex our transformers.
Never questioned it. I guess I thought it was required.

MDShunk · 04-16-2007, 10:13 PM

I've only ever had to change-out but a few transformers, but I appreciated the fact that the final connection was done with flex. Made the swap a lot easier.