Install Question

Status
Not open for further replies.
A

Alwayslearningelec

Senior Member
Location
NJ
Occupation
Estimator
So related to my temp scenario:

We were not able to procure a outdoor branch panel in time so we are using (3) disconnect switches to feed the disconnects/trailers.

I proposed coming out of the secondary side of the xfrm with the (3) cables to each of the (3) 2 pole disconnects(125A,60A &60A) 25' away.

The foreman said he would rather not come out of the transformer with three cables. I think he's not sure how wire three cables to the secondary side of the xfrmr...... I think it would be phae A-B, B-C and A-C, correct?

He would rather now run one larger cable from the transformer mount a splice box and splice down to the (3) cables for the 125A, 60A and 60A disconnect.
I think he's creating more work by doing it this way. Any thoughts?
 
horsegoer said:
So related to my temp scenario:

We were not able to procure a outdoor branch panel in time so we are using (3) disconnect switches to feed the disconnects/trailers.

I proposed coming out of the secondary side of the xfrm with the (3) cables to each of the (3) 2 pole disconnects(125A,60A &60A) 25' away.

The foreman said he would rather not come out of the transformer with three cables. I think he's not sure how wire three cables to the secondary side of the xfrmr...... I think it would be phae A-B, B-C and A-C, correct?

He would rather now run one larger cable from the transformer mount a splice box and splice down to the (3) cables for the 125A, 60A and 60A disconnect.
I think he's creating more work by doing it this way. Any thoughts?
Click to expand...
I am confused. Are you proposing to basically parallel the three separate cables to the secondary of the transformer and go to the separate disconnects from there?
 
I was proposing to run. (2) 3/c # 4 cable and a 3/c #2/0 from the secondary side of xfmr to the three disconnects. I don’t think the electrician thinks it’s allowed(or wants to) to have three separate cable run out of a xfmr.
 
horsegoer said:
I was proposing to run. (2) 3/c # 4 cable and a 3/c #2/0 from the secondary side of xfmr to the three disconnects. I don’t think the electrician thinks it’s allowed(or wants to) to have three separate cable run out of a xfmr.
Click to expand...
I don't see the difference in the two things mentioned.
 
horsegoer said:
I was proposing to run. (2) 3/c # 4 cable and a 3/c #2/0 from the secondary side of xfmr to the three disconnects. I don’t think the electrician thinks it’s allowed(or wants to) to have three separate cable run out of a xfmr.
Click to expand...
A 3/c conductor cable. Did you mean 4/c conductor cable?
 
augie47 said:
IMO, what he proposes would not be allowable under 240.2(C) tap rules as the 25' secondary conductors are required to terminate at an overcurrent device,
Click to expand...
he could run full size conductors to the tap box. He would need some kind of secondary OCPD though. But he would probably need that anyway unless these are service conductors.
 
Can you run (3) 3/c cables from a xfmr as I describe. It’s sounds very unusual but was told you could do that. Really o my every see one cable/conduit l from a xfrmr.
 
You are allowed more than one set of conductors on a transformer secondary as long as you follow 450,3
(Note 2 limits it to six where secondary protection is required.
 
I think the only issue may be what Angie mentioned, I would review that with your disconnect locations
 
horsegoer said:
Can you run (3) 3/c cables from a xfmr as I describe. It’s sounds very unusual but was told you could do that. Really o my every see one cable/conduit l from a xfrmr.
Click to expand...
In your situation the number of cables is not an issue (it's not over 6), but you would need 4 conductors.. H-H-N-& SSBJ.
 
Ok my foreman says you “can’t tap” a transformer 3 times so per NEC code you can’t go into a transformer and terminate (3) 3/c or 4/c cables. True ?
 
Note 2: Where secondary overcurrent protection is required, the secondary overcurrent device shall be permitted to consist of not more than six circuit breakers or six sets of fuses grouped in one location. Where multiple overcurrent devices are utilized, the total of all the device ratings shall not exceed the allowed value of a single overcurrent device.
 
Last edited:
horsegoer said:
Ok my foreman says you “can’t tap” a transformer 3 times so per NEC code you can’t go into a transformer and terminate (3) 3/c or 4/c cables. True ?
Click to expand...
Nope,
augie47 said:
Note 2: Where secondary overcurrent protection is required, the secondary overcurrent device shall be permitted to consist of not more than six circuit breakers or six sets of fuses grouped in one location. Where multiple overcurrent devices are utilized, the total of all the device ratings shall not exceed the allowed value of a single overcurrent device.
Click to expand...
NOT true.
 
Status
Not open for further replies.
Top