(transformer). Readily accessible disconnecting means within sight of equipment.

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victor.cherkashi

Senior Member
Location
NYC, NY
Readily accessible disconnecting means within sight is required for many equipments, but I can't find in NEC requirement for a transformer. It doesn't make sense for me to see 1000 KVA dry transformer in a room which has primary winding switch 400 feet away (in main electrical room).
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Readily accessible disconnecting means within sight is required for many equipments, but I can't find in NEC requirement for a transformer. It doesn't make sense for me to see 1000 KVA dry transformer in a room which has primary winding switch 400 feet away (in main electrical room).

how often are you going to need to open the switch? once every decade?
 

dkidd

Senior Member
Location
here
Occupation
PE
Look at 450.14

450.14 Disconnecting Means. Transformers, other than Class
2 or Class 3 transformers, shall have a disconnecting means
located either in sight of the transformer or in a remote location.
Where located in a remote location, the disconnecting
means shall be lockable in accordance with 110.25, and its
location shall be field marked on the transformer.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
It seems we take advantage of that as I have not seen us installing disconnects for transformers yet and we are under the 2014.
In reality almost all transformers have disconnects in the form of their primary OCPD. The only real change in the 2014 code is the label requirement if the disconnect is not local to the transformer.
 

JJtechguy

New member
Location
Fairfield, IA
Transformer disconnect

Transformer disconnect

I have noticed people mounting disconnects to the outside of dry type transformers. This appears to be sloppy work in my opinion. Has anyone else seen this done? Is there a code violation? If so please give me a reference.
 

ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
I have noticed people mounting disconnects to the outside of dry type transformers. This appears to be sloppy work in my opinion. Has anyone else seen this done? Is there a code violation? If so please give me a reference.

Where are you seeing this and why would anyone do it? What don said is entirely correct so there is no reason for a disconnect, just a label.
 
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