Transformer UL label

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I am required to prove that I was not negligent when I approved a 150 KVA pad mount transformer that was not UL labeled. The AHJ on his final inspection refused to approve the unit because he maintains that NEC requires all transformers to be UL listed and Labeled. The Manufacturer disagrees and the Contractor wants to be paid to have the transformer NRTL labeled instad. The Owner refuses to pay.
 

iwire

Moderator
Staff member
Location
Massachusetts
Re: Transformer UL label

I doubt any pad mount transformer from any manufacturer has a UL listing.

Did the inspector cite a code section to back his position?
 

iwire

Moderator
Staff member
Location
Massachusetts
Re: Transformer UL label

90.7 Examination of Equipment for Safety.
For specific items of equipment and materials referred to in this Code, examinations for safety made under standard conditions provide a basis for approval where the record is made generally available through promulgation by organizations properly equipped and qualified for experimental testing, inspections of the run of goods at factories, and service-value determination through field inspections. This avoids the necessity for repetition of examinations by different examiners, frequently with inadequate facilities for such work, and the confusion that would result from conflicting reports on the suitability of devices and materials examined for a given purpose.
It is the intent of this Code that factory-installed internal wiring or the construction of equipment need not be inspected at the time of installation of the equipment, except to detect alterations or damage, if the equipment has been listed by a qualified electrical testing laboratory that is recognized as having the facilities described in the preceding paragraph and that requires suitability for installation in accordance with this Code.
Some examples

352.6 Listing Requirements.
RNC, factory elbows, and associated fittings shall be listed.
411.3 Listing Required.
Lighting systems operating at 30 volts or less shall be listed for the purpose.
358.6 Listing Requirements.
EMT, factory elbows, and associated fittings shall be listed.
I am sure there are others.

I can not find anything in the article 450 requiring a transformer to be listed.

90.4 gives the AHJ the responsibility for approving equipment is the inspector you are dealing with also the AHJ or can you appeal the inspectors decision to a higher office?
 

sandsnow

Senior Member
Re: Transformer UL label

I agree with Bob on this that XFMR's are not required to be listed by the Code.
What you have to look at is 110-3(b). It lays out the parameters of judging equipment for suitability. The AHJ is supposed to judge equipment based on this. What happens is that AHJ's don't know how or don't want to make the the call, they want to rely on UL or other NRTL to do it for them hence they want XFMR's and other equip to be listed. We require equipment to be listed here, but we have a Bulletin signed by the Chief Building Official that requires it.
If the padmount is from a reputable manufacturer, the fact it is not listed shouldn't be a problem. Request their test data along the items in 110-3(a). If you get a third party testing agency, one of the small ones that are affordable; that's all they will do besides poke their head in the case and take some measurments. They sure won't test to failure like a XFMR would go through at UL.
Good Luck on this
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
Re: Transformer UL label

You might also look at Appendix A:

This informational annex provides a list of product safety standards used for product listing where that listing is required by this Code . It is recognized that this list is current at the time of publication but that new standards or modifications to existing standards can occur at any time while this edition of the Code is in effect.
While it is not Code in itself, it is a comprehensive table of equipment "... where that listing is required by this Code " . You won't find transformers; they aren't "specifically" required by the NEC. [See the first sentence of Section 90.7]

The intent (not requirement) of "listing" is spelled out in the second paragraph.

There is one other potential issue you may want to review though: FedOSHA's 29CFR1910 Section 399 . See the definitions of "Approved" and "Accepted."

You should also check UL's Online Compliance Directory and do a Category Code search on "XPLH." Check-off the "Guide Information Only Box" to get the scope only. Do the same search with the box unchecked.
 

sandsnow

Senior Member
Re: Transformer UL label

Bob
Thanks for pointing out the UL site. I didn't know that liquid filled XFMR's were listed now. In the past only dry type at over 600V were listed.
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
Re: Transformer UL label

You're welcome Larry, :D

[ August 25, 2004, 01:16 PM: Message edited by: rbalex ]
 
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