Transformer Secondary Protection?

Bigjabe

Member
Location
Vancouver BC
Hello,

I have a situation where it's 13.8kV pole-mount transformers protected at 125% by fuse cutouts, then conductors down to a panelboard mounted to the pole. The inspector is saying we need a main breaker on the panel. The transformers are 3 x 100kVA (289A FLA) protected by 15A fuses (which is 345A secondary current) and the panelboard is 400A.

Do I really need a main breaker on the panel?
 

Bigjabe

Member
Location
Vancouver BC
Under the NEC you sure do for a number of reasons. I'm sure the CEC is similar. Is this a service? That adds other issues.
No, it's just a tap off a private 13.8kV line at an industrial site. Other than simple convenience of disconnecting without operating the fuse cutouts, what are the reasons/code clauses?

Edit: sorry I didn't mention that the secondary voltage is 600V
 

bwat

EE
Location
Western PA
Occupation
EE
My question is (probably incorrectly) assuming similarities between NEC and CEC, but how many breakers are in the panelboard and what are their ratings? In NEC I believe there could be some ways where you don't need a main breaker. (supervised and industrial locations..)
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
My question is (probably incorrectly) assuming similarities between NEC and CEC, but how many breakers are in the panelboard and what are their ratings? In NEC I believe there could be some ways where you don't need a main breaker. (supervised and industrial locations..)
There are no "supervises and industrial locations" exception to the rule in 408.36 that requires a panelboard to be protected by a single main.
 

bwat

EE
Location
Western PA
Occupation
EE
There are no "supervises and industrial locations" exception to the rule in 408.36 that requires a panelboard to be protected by a single main.
Valid point. The transformer protection and secondary conductor protection may have some exceptions like this that allow the lack of a main on the panelboard, but harder to get there when considering the protection of the panelboard requirement. 408.36 lists 240.21(C)(1) as a possibility for protection via the primary, but I don’t think that applies here. So it might actually be a panelboard protection requirement that drives the actual need here. Could all be moot anyway (NEC vs CEC).
 
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