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#38273 - 05/19/04 06:56 PM Dry Transformer Primary & Secondary Conduits
master66 Offline
Member

Registered: 04/18/02
Posts: 260
Loc: Masontown, PA, USA
Tell me if there is any problem with the following methods of running conduit to a dry type transformer.

Transformer is sitting on a concrete floor. The primary and secondary conduits are brought directly up into the bottom of the transformer using the proper box connector.

Same situation but stubbing PVC in to the bottom of the transformer with no connector.

Transformer is sitting on floor or hung. A small section of trough or a properly sized pull box is mounted to the side of the transformer where the conductors enter the transformer via chase nipples. The primary and secondary conduits are directly connected to the trough or pull box with no flex. (I know flex is not required)

We were discussing these methods at work today and I'm not sure if there is anything wrong with any of the above methods or not.

They all seem OK although I'm not crazy about stubbing the PVC into the transformer without a connector.

I've always fed the transformer via flex. Just seemed like the easiest way but it can get expensive.

What do you guys think?

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#38274 - 05/19/04 06:59 PM Re: Dry Transformer Primary & Secondary Conduits
Ryan_J Offline
Moderator

Registered: 08/19/03
Posts: 1355
Loc: West Jordan, Utah, USA
PVC with no connector would violate 300.4(F), if the conductors are 4 AWG or larger.
_________________________
Ryan Jackson,
Salt Lake City

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#38275 - 05/19/04 07:13 PM Re: Dry Transformer Primary & Secondary Conduits
elektrikguy Offline
Member

Registered: 05/25/02
Posts: 133
Loc: woodstock,ga,usa
You could stub up with pvc and put a coupling so that the top is flush with the bottom of the transformer. Then you could use an adapter like the one pictured on page 15. You would not have to lift over threads and risk damaging them. Just shimmy the unit to line up the knock-out that you had made and slide the adapter on. Low profile and allows immediate bending if conductors.
http://www.beckmfg.com/pricesheets/pvc082.pdf

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#38276 - 05/19/04 07:49 PM Re: Dry Transformer Primary & Secondary Conduits
master66 Offline
Member

Registered: 04/18/02
Posts: 260
Loc: Masontown, PA, USA
Ryan,

I was always under the impression that bushings were not required with PVC conduit.

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#38277 - 05/19/04 07:51 PM Re: Dry Transformer Primary & Secondary Conduits
fla sparkey Offline
Member

Registered: 08/03/02
Posts: 46
Loc: Winter Haven, Florida USA
Trust me, they are #4 and larger.

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#38278 - 05/19/04 07:52 PM Re: Dry Transformer Primary & Secondary Conduits
Ryan_J Offline
Moderator

Registered: 08/19/03
Posts: 1355
Loc: West Jordan, Utah, USA
I was too. In fact, I couldn't tell you how many times I've installed like this into the bottom of an MDP or MCC.

I hate to say it, but there is no exception for RNC to that rule.
_________________________
Ryan Jackson,
Salt Lake City

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#38279 - 05/19/04 08:17 PM Re: Dry Transformer Primary & Secondary Conduits
Ryan_J Offline
Moderator

Registered: 08/19/03
Posts: 1355
Loc: West Jordan, Utah, USA
.

[This message has been edited by Ryan_J (edited 05-20-2004).]
_________________________
Ryan Jackson,
Salt Lake City

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#38280 - 05/20/04 09:11 AM Re: Dry Transformer Primary & Secondary Conduits
resqcapt19 Offline
Member

Registered: 11/10/00
Posts: 2209
Loc: IL
 Quote:
352.46 Bushings.
Where a conduit enters a box, fitting, or other enclosure, a bushing or adapter shall be provided to protect the wire from abrasion unless the box, fitting, or enclosure design provides equivalent protection.
_________________________
Don(resqcapt19)

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#38281 - 05/20/04 02:56 PM Re: Dry Transformer Primary & Secondary Conduits
master66 Offline
Member

Registered: 04/18/02
Posts: 260
Loc: Masontown, PA, USA
OK, I understand the bushing issue but what about the methods that I described?

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#38282 - 05/20/04 03:03 PM Re: Dry Transformer Primary & Secondary Conduits
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
As long as you get some bushings on the PVC method all of the ways you describe are fine.

I have come up in the bottom, used flex, trough, EMT, etc.

As long as you come in where the instructions allow, usually below the terminals.
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts

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