Power taps

[bigdog]

I'm designing a conveyor system. On this system I have 11 sub-enclosures and one main enclosure. The power for the systeme is 208VAC, 3 phase, 4 wire, 60 Hz, 60 amps. Also there's 4" X 4" (hoffman) wireway (layin type) that connects all the enclosures together. The question that I have, is it legel to tap (split lug) off the 208VAC, and have that tap in the wireway.

 

[DanDel]

Feeder taps are limited in the NEC by Art. 240.21(B). Check this out for your particular requirements, since you did not include any specifics.

 

[bigdog]

DanDel,

What specifics do you require?

 

[DanDel]

Tap conductor lengths, overcurrent device ratings, circuit types, etc. Check out the NEC.

 

[bigdog]

DanDel,

Main feed conductor is 40 ft. long, the main fuse is a type J 60 Amp fuse, and voltage to be used is 208VAC, 3 Phase, 4 wire.

I hope this is enough information.

 

[DanDel]

bigdog, the information you are providing is not enough for me to make this decision for you. You must either consult the NEC yourself or hire an electrician or engineer to look at the system and/or wire it.

 

[REDDOG]

Tap rule 1/3 ampacity of tapped conductor no longer than 25 feet and end IN A SINGLE SET OF OVERCURRENT DEVICES ie a cb or fuse. Each cabinet must have a disconnect switch.
A # 12 conductor and a 20 amp cb or fused disconnect.

 

[bigdog]

Ok!! now I understand what your asking DanDel.
Each sub-enclosure has it's own disconnect switch and primary fusing. The primary fuse for each sub-enclosure is between 15 to 10 amps.

 

[jbartos]

Suggestion: The mentioned 1/3 amp 25ft rule is to be applied carefully since the tap of 1/3 amp conductor may become hot due to various leaks within 25ft, and this may damage insulation of the main feeder. It appears that the rule is more fitted to busbars which may overheat since they do not have any insulation.
It may be better to provide the normal power distribution with properly protected branches.
Also, to be on the safe side, the 1/3 may be increased, however, then it is better to look into an engineering trade-off, namely, which solution is better.