I've got a question that I'd like to get a few opinions on.
Say I've got a (outside) self contained Heat Pump/AC unit for a Mobile Home. It also has 15KW auxiliary heat strips.
This is a replacement unit for the original split unit....electric heat inside, A/C compressor outside.
This is for a friend....trying to save money....etc....you know...
There is a existing #10cu NM feeder, existing 6/2cu SE feeder, and I plan on adding a additional #8cu NM feeder (and re-routing the others) to supply the new unit (3 circuits total).
I plan on setting (3) seperate disconnects on the outside of the house, hitting them with the (3) seperate feeder circuits, connecting all (3) disconnects together with PVC conduit, and then running (1) LFNMC (containing all 3 circuits) from the center disconnect to the unit and powering the circuits in the unit individually...I hope that's clear.
Wire fill and de-rating in the LFNMC is not a problem.
All of the feeders contain a #10cu Grounding conductor, and the largest circuit will be 50 amps (240V).
My question.
Do I have to bring all 3 of the feeder grounding conductors to and bond each disconnect?
I'm pretty sure that I do.
I plan on jumpering between (bonding together) each disconnect with a #10cu, and then running (1) #10 grounding conductor from one of the disconnects to the A/C unit.
Although the disconnects (and circuits) are seperate, I believe that 250.134(B) prevents me from using the grounding conductor run with each feeder to (only) bond the (associated) disconnect enclosure and then running (1) equipment ground from any of the disconnects to the unit.
More clearly.....If I've got 3 seperate circuits with 3 seperate grounding conductors, and they will ultimately terminate at a single point, I have to use all of the (feeder) grounding conductors and bond them together at their termination.
I think that I've answered my own question.:smile:
Any response?
thanks
steve
Say I've got a (outside) self contained Heat Pump/AC unit for a Mobile Home. It also has 15KW auxiliary heat strips.
This is a replacement unit for the original split unit....electric heat inside, A/C compressor outside.
This is for a friend....trying to save money....etc....you know...
There is a existing #10cu NM feeder, existing 6/2cu SE feeder, and I plan on adding a additional #8cu NM feeder (and re-routing the others) to supply the new unit (3 circuits total).
I plan on setting (3) seperate disconnects on the outside of the house, hitting them with the (3) seperate feeder circuits, connecting all (3) disconnects together with PVC conduit, and then running (1) LFNMC (containing all 3 circuits) from the center disconnect to the unit and powering the circuits in the unit individually...I hope that's clear.
Wire fill and de-rating in the LFNMC is not a problem.
All of the feeders contain a #10cu Grounding conductor, and the largest circuit will be 50 amps (240V).
My question.
Do I have to bring all 3 of the feeder grounding conductors to and bond each disconnect?
I'm pretty sure that I do.
I plan on jumpering between (bonding together) each disconnect with a #10cu, and then running (1) #10 grounding conductor from one of the disconnects to the A/C unit.
Although the disconnects (and circuits) are seperate, I believe that 250.134(B) prevents me from using the grounding conductor run with each feeder to (only) bond the (associated) disconnect enclosure and then running (1) equipment ground from any of the disconnects to the unit.
More clearly.....If I've got 3 seperate circuits with 3 seperate grounding conductors, and they will ultimately terminate at a single point, I have to use all of the (feeder) grounding conductors and bond them together at their termination.
I think that I've answered my own question.:smile:
Any response?
thanks
steve
