I have a inspector that wants us to install a fusable disconect on the load side of a transformer. What there is now- a transformer that is fed from switch gear, then it is triple taped for 3 main breaker panels(all withen 6 feet). Is the disconect on the load side required?
Triple tap transformer
- Thread starter chrsb
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ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Re: Triple tap transformer
First determine if secondary protection is required, then what is the total of the three main breaker (add them up) as compared to the maximum size that the single disconnects fuses would be.
See Note 2 to Table 450.3(B)
First determine if secondary protection is required, then what is the total of the three main breaker (add them up) as compared to the maximum size that the single disconnects fuses would be.
See Note 2 to Table 450.3(B)
electricman2
Senior Member
- Location
- North Carolina
- Occupation
- Retired Electrical Contractor
Re: Triple tap transformer
If the primary is fused at 300A as you say then secondary protection is not required. However protection is required for the secondary conductors. See 240.21(C) for these requirements.
If the primary is fused at 300A as you say then secondary protection is not required. However protection is required for the secondary conductors. See 240.21(C) for these requirements.
charlie
Senior Member
- Location
- Indianapolis
Re: Triple tap transformer
There are two things to look at for protection. First, you have to protect the transformer in accordance with Article 450 which is only concerned with the transformer. Secondly, you have to protect the transformer taps in accordance with Article 240 which is only concerned with the conductors (I wonder if an Article can be concerned about anything? HMMM)
BTW, a transformer can have an unlimited number of taps.
There are two things to look at for protection. First, you have to protect the transformer in accordance with Article 450 which is only concerned with the transformer. Secondly, you have to protect the transformer taps in accordance with Article 240 which is only concerned with the conductors (I wonder if an Article can be concerned about anything? HMMM)
BTW, a transformer can have an unlimited number of taps.
- Location
- Massachusetts
Re: Triple tap transformer
[ July 10, 2004, 06:45 PM: Message edited by: iwire ]
Only if it has a sense of responsibility.
[ July 10, 2004, 06:45 PM: Message edited by: iwire ]
Re: Triple tap transformer
So it is already is code compliant, I thought it was but wanted to make sure. I am biding on a job that went BK and was 80% complete. I did the original work and they are keeping the first floor exactly the same. The only bad thing is the inspector is making me move the main 2000 amp switch, after he already approved it on the previous job. He wants the 2 exits to the room. I don't see how he can change his mind like that, there was a 1600 amp switch(which is still over 1200 amps) which he approved. Now we have to shut the mall down, find the pipes, cut the concrete, and have it all done on a Sunday.
So it is already is code compliant, I thought it was but wanted to make sure. I am biding on a job that went BK and was 80% complete. I did the original work and they are keeping the first floor exactly the same. The only bad thing is the inspector is making me move the main 2000 amp switch, after he already approved it on the previous job. He wants the 2 exits to the room. I don't see how he can change his mind like that, there was a 1600 amp switch(which is still over 1200 amps) which he approved. Now we have to shut the mall down, find the pipes, cut the concrete, and have it all done on a Sunday.
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