Transformer - minimum side clearance

Status
Not open for further replies.
C

cppoly

Senior Member
Location
New York
What's a good estimation for the minimum clearances you would need for a transformer for the primary and secondary conductors entering / leaving the sides, 12"?
 
You would need the radius of the raceway elbow, or the width of an LL or LR fitting.
I don't think I have never seen a transformer with sidewall clearance restrictions.
 
If you look at the spec sheet for said transformer, it will give you minimum clearance.
The spec sheet for a siemens dry type 150 KVA, 480 to 208/120V, 4.8% impedance that I am staring at right now states:
"Spacings between any ventilated enclosure panel and any adjacent wall shall be a minimum of 5 inches except when wall mounted using approved wall mounting kit"
Since the transformer typically sits on the ground and the panel feeding it and receiving it typically sit much higher, conduit or flexible conduit clearance distances usually aren't an issue.
So please ask for the spec sheet on your transformer. If you absolutely have to guess, I believe 6" would be a safe bet if your transformer is 150 KVA or below.
The NEC code book may have some additional comments, but I will let you or someone else chase after that.
 
Last edited:
powerpete69 said:
If you look at the spec sheet for said transformer, it will give you minimum clearance.
The spec sheet for a siemens dry type 150 KVA, 480 to 208/120V, 4.8% impedance that I am staring at right now states:
"Spacings between any ventilated enclosure panel and any adjacent wall shall be a minimum of 5 inches except when wall mounted using approved wall mounting kit"
Since the transformer typically sits on the ground and the panel feeding it and receiving it typically sit much higher, conduit or flexible conduit clearance distances usually aren't an issue.
So please ask for the spec sheet on your transformer. If you absolutely have to guess, I believe 6" would be a safe bet if your transformer is 150 KVA or below.
Click to expand...
The spacing you mentioned is for free air around the transformer for cooling, OP is asking about clearance to allow conductors to enter from a side wall.

Answer really depends on wiring method and size involved. Minimum air space needed around the unit may be greater than what is needed for some wiring methods.
 
See attached picture. In this setup you would just consider vertical clearances per conduit allowable bends.
 

Attachments

  • 2 panels and xformer.pdf
    107.6 KB · Views: 37
powerpete69 said:
"Spacings between any ventilated enclosure panel and any adjacent wall shall be a minimum of 5 inches except when wall mounted using approved wall mounting kit"
Click to expand...

Where in that spec does it mention clearance for non-ventilated enclosure panels?
 
cppoly said:
What's a good estimation for the minimum clearances you would need for a transformer for the primary and secondary conductors entering / leaving the sides, 12"?
Click to expand...

12" would work for just about any FMC 90° connector.
 
Status
Not open for further replies.
Top