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ekstra   ara
 Post subject: Label Transformers?
PostPosted: Wed Jul 17, 2013 4:00 pm 

Joined: Mon Jul 15, 2013 9:47 am
Posts: 3
The facility I am working at has several transformers below 150 kVA that step down from 480 V to 208/120V. Does this require a label if these transformers are rarely examined or checked for voltage? Not as a maintenance procedure but in other situations.


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PostPosted: Mon Jul 22, 2013 5:12 am 

Joined: Thu Mar 28, 2013 1:15 pm
Posts: 2
My company typically includes a bus for the secondary of transformer for information purposes (edit: I mean we include a bus in our analysis software), and we include the label for the transformer in our deliverables if requested, but strictly speaking, if the transformer is not going to be "examined, adjusted, serviced or maintained..." (NEC 110.16) then it will not need a label.

Transformer secondaries are invariably the most dangerous portion of any delivery and they should not be worked on live (of course, nothing should, but these especially).


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PostPosted: Mon Jul 22, 2013 6:20 am 
Sparks Level

Joined: Fri Apr 15, 2011 7:43 am
Posts: 177
Location: Colorado
I agree with Don. XFMR's are generally the most dangerous piece of equipment and any downstream bus. I tell my engineers to make a label if may be entered easily by turning a screw or two or for trouble shooting.


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PostPosted: Mon Jul 22, 2013 7:59 am 

Joined: Mon Nov 19, 2007 5:25 am
Posts: 32
Location: Titusville, Fl.
Agree transformer secondaries are very dangerous, but sometimes critters find there way in them evident by undervoltages that may require cleaning/repairs...Also, what if you have to remove or replace (R&R) such unit? Will it require PPE to verify off following a LOTO activity, at the secondary? My receommendation for these cases is to field verify and/or check drawing for the solid connection of downstream panels to such secondary. Then at such panel verify off via load side of the main breaker, or smallest breaker (less arc energy, but verify main is closed or could be a load panel w/o main), then proceed to R&R/cleaning of the transformer.


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