Cheers, Wayne2011 NEC wrote:334.80 Ampacity. The ampacity of Types NM, NMC, and NMS cable shall be determined in accordance with 310.15. The allowable ampacity shall not exceed that of a 60°C (140°F) rated conductor. The 90°C (194°F) rating shall be permitted to be used for ampacity adjustment and correction calculations, provided the final derated ampacity does not exceed that of a 60°C (140°F) rated conductor.
One more question, this is feeding a small (four space) sub panel, is the "calculation" the sum of the amps of the breakers in the sub panel? As a practical matter none of these loads is continuous, eg a boat lift. Basically we have 6/3 romex feeding a string of LED Christmas lights on the dockwwhitney wrote:...provided that the calculated load is 55A or less.
No, the calculation is done per Article 220 of the NEC. As a practical matter, the sum of the breakers will be an overestimate of the load, often a very large overestimate. On the other hand, if the run is long, you will need to upsize the conductors to account for voltage drop.LTLFTcomposite wrote: One more question, this is feeding a small (four space) sub panel, is the "calculation" the sum of the amps of the breakers in the sub panel?
This 6/3 Romex is only for the indoor portion of the run? Because NM cable is only for use in dry locations, and any outdoor location (even inside conduit) is considered a wet location.LTLFTcomposite wrote: As a practical matter none of these loads is continuous, eg a boat lift. Basically we have 6/3 romex feeding a string of LED Christmas lights on the dock
That's a Canadian term, right? I think the Canadian Electrical Code is a bit more enlightened in this regard and doesn't restrict NM cable to the 60C ampacity, although I don't know the details.camasleaf wrote:I stand corrected. I was thinking about NMD90.