I am questioning the size of tap conductors used in 3 phase, 208 volt, 500 amp fused disconnects. The disconnects were installed in the late 1950's and fed with 2- 250 mcm cables per phase. During my inspection I noticed on different disconnects #8 and #6 wires inserted in with the 250 mcm cables. These wires then feed smaller disconnects adjacent to this disconnect. From a visual stand point these much smaller wires in the same lug with a 250 mcm look out of place. Does the NEC limit the size of these tap conductors?
Feeder Taps
- Thread starter dime
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- Massachusetts
This is not a yes or no question.
There rules can be found in 240.21(B).
In general the size of the tap conductor is not limited if the length is less than 10' assuming compliance with all of 240.21(B)(1)
If the tap is 10' to 25' in length it will need to have an ampacity of one third of the OCPD for the feeder. (240.21(B)(2)
The obvious violation is of 110.14(A) which requires the terminal to be listed for the conductors installed.
However I don't know when 110.14(A) became effective.
It may have been OK at the time of installation which generally means its OK now.
There rules can be found in 240.21(B).
In general the size of the tap conductor is not limited if the length is less than 10' assuming compliance with all of 240.21(B)(1)
If the tap is 10' to 25' in length it will need to have an ampacity of one third of the OCPD for the feeder. (240.21(B)(2)
The obvious violation is of 110.14(A) which requires the terminal to be listed for the conductors installed.
However I don't know when 110.14(A) became effective.
It may have been OK at the time of installation which generally means its OK now.
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