XO 10' rule

[dana1028]

I frequently inspect tenant spaces where the landlord installs a 75kVA XO with a 225A, 208Y/120 distribution panel [with main] on the secondary; primary is 100A @ 480 - all conductors are sized correctly [usually #2's on the primary & 4/0 on the secondary]

Sometimes the electrician's really struggle to get the panel within the 10' rule [limited space, other structural problems, etc.]

Given the above type of installation, I see no reason these panels should not be allowed to be up to 25' from the XO [240.21(C)(6)].

Am I corrrect?

Note - this is commercial retail space and I never see upsized primary or secondary OCP.

 

[chris kennedy]

Never mind.

 

[augie47]

I'd say you are correct

 

[mcclary's electrical]

Never mind.

Now that's funny.
How about bright as a burnt out light bulb or
sharp as a bowling ball or
dumb as a door nail or
.........:grin:

 

[brian john]

I frequently inspect tenant spaces where the landlord installs a 75kVA XO with a 225A, 208Y/120 distribution panel [with main] on the secondary; primary is 100A @ 480 - all conductors are sized correctly [usually #2's on the primary & 4/0 on the secondary]

Sometimes the electrician's really struggle to get the panel within the 10' rule [limited space, other structural problems, etc.]

Given the above type of installation, I see no reason these panels should not be allowed to be up to 25' from the XO [240.21(C)(6)].

Am I corrrect?

Note - this is commercial retail space and I never see upsized primary or secondary OCP.

XO? The secondary neutral/grounded conductor?

 

[infinity]

I see no reason why you cannot use the 25' rule providing all of the parameters of 240.21(C)(6).

240.21(C)(6) Secondary Conductors Not over 7.5 m (25 ft) Long. Where the length of secondary conductor does not exceed 7.5 m (25 ft) and complies with all of the following:
(1) The secondary conductors shall have an ampacity that is not less than the value of the primary-to-secondary voltage ratio multiplied by one-third of the rating of the overcurrent device protecting the primary of the transformer.
(2) The secondary conductors terminate in a single circuit breaker or set of fuses that limit the load current to not more than the conductor ampacity that is permitted by 310.15.
(3) The secondary conductors are protected from physical damage by being enclosed in an approved raceway or by other approved means.

 

[dana1028]

XO? The secondary neutral/grounded conductor?

sorry - use that as a short version of xfrmr

thanx for the replies.