I had a question about sizing a non-fused service disconnect for a VRV which has a nameplate of MCA:58.3 MOP:70, and RLA:42.6. From what I have read and understand is that I can size the non fused service disconnect off the MCA for a 60 amp rated disconnect where if it were fused I would have to go with a 100amp rated disconnect and 70 amp fuses. Any help would be appreciated
Sizing Disconnect for VRV
- Thread starter pins2621
- Start date
440.12(A)(1) exception gives you guidance....
(1) Ampere Rating. The ampere rating shall be at least 115 percent of the nameplate rated-load current or branchcircuit selection current, whichever is greater. E
Exception: A listed unfused motor circuit switch, without fuseholders, having a horsepower rating not less than the equivalent horsepower determined in accordance with 440.12(A)(2) shall be permitted to have an ampere rating less than 115 percent of the specied current.
It appears the 60 amp NF switch might be allowed but you need the check the HP rating and apply the above criteria
(1) Ampere Rating. The ampere rating shall be at least 115 percent of the nameplate rated-load current or branchcircuit selection current, whichever is greater. E
Exception: A listed unfused motor circuit switch, without fuseholders, having a horsepower rating not less than the equivalent horsepower determined in accordance with 440.12(A)(2) shall be permitted to have an ampere rating less than 115 percent of the specied current.
It appears the 60 amp NF switch might be allowed but you need the check the HP rating and apply the above criteria