Stranberg
New member
- Location
- Kent, Washington
I have an electric coil fan powered (VAV) box that is rated at 208v, 3 phase, 12kw. The nameplate shows a minimum circuit ampacity of 56.3 amps and a maximum overcorrect protection of 60 amps. The heater amps is 33.3 amps which is consistent with the wattage rating of the unit. The motor is 3/4hp, 11.8 FLA at 115v, which is tapped off of the ?a? phase at the terminal block inside the unit which is consistent with the minimum circuit ampacity of both combined loads x 125%. I have an existing 1? EMT conduit which is feeding (2) of these units. Table C.1 shows that I can get (7) #6 conductors in a 1? EMT conduit, but I would need (8) #6, (4) each if the grounded conductor is rated at 100% of the circuit.
What I would like to do is to downsize the grounded conductor to #10, the same size as the EGC, and sufficient for the unbalanced load of 11.8 amps. Looking in 210, 220, and 424, I can not find anything that tells me this is acceptable. There are similar conditions like household cooking appliances where this is allowed, as stated in 210.19(a)3.
Does anyone have any experience or insight as to where this would be considered acceptable or not.
Thank you in advance for your help!
What I would like to do is to downsize the grounded conductor to #10, the same size as the EGC, and sufficient for the unbalanced load of 11.8 amps. Looking in 210, 220, and 424, I can not find anything that tells me this is acceptable. There are similar conditions like household cooking appliances where this is allowed, as stated in 210.19(a)3.
Does anyone have any experience or insight as to where this would be considered acceptable or not.
Thank you in advance for your help!