Install a NEMA 6-50 plug off the new 50 amp breaker in the subpanel.Install a 50 amp breaker in the new Subpanel.Hang the ClipperCreek or Porsche Wall Charger off the new 60 amp breaker - configure as appropriate.Install a 60 amp breaker in the new subpanel.run appropriate wire gauge from the new breaker to a new sub-panel in the garage.Install a 125 amp breaker in the main panel.purchase a dedicated wall mounted charger (ClipperCreek 60/80/100 or Porsche Wall Charger).In the US you can breaker it as high as 90A, it's up to you. In Canada you must nanny-breaker that for 50A. because that's considered "not a gongshow" even in Canada! Since 40A is 80% of our 50A breaker trip.
Wire size for 50 amp breaker crack#
Crack a Molson and have some Tim Hortons donuts, eh. Now this calculates straight to 2.93% at 40 amps. Since that is a subpanel, you can breaker the XHHW #4AL feeder to 70A. However, if you're doing an RV stand, I suggest using an "RV stand subpanel" which gives you a 14-50 for large RVs, a TT30 for small RVs, and a 120V/20A GFCI for incidental loads. Now if you're going to a 50A receptacle, you must stay at 50A because the receptacle amps must match the breaker amps. We can use a 65A breaker because our country doesn't require "nanny breakers" lol! (since 65A breakers aren't made, you round up to 70A).
Most cables: 6 AWG copper (55A 60C) or 4 AWG aluminum (55A).(literally they let you go 90C, but, the terminations at both ends are only rated 75C, so you are capped at 75C. Noting that most cable puts you in the 60C column, and wires-in-conduit (because of their THHN or XHHW insulation) let you use the 75C column. You don't need to multiply that by 125%.Īrmed with that number, you find the minimum cable size that exceeds it in Table 310.15(B)(16). you follow the provisioning rules - for instance an RV stand of 20/30/50A requires 50A provisioned.start with your actual load and multiply by 125%, so for instance if you have a 39A hot tub, you must multiply by 125% to get 48.75A, which rounds up to 50A.The two calculations you must doįirst, you must determine the absolute minimum wire size, even if the cable were only 1 foot long. It's "legal" to put cable in conduit, but the conduit must be larger for the same current, for a couple reasons: First, most cables are only rated for 60C temperature, so you need larger cable and second, the cable sheath adds a great deal of bulk - the conduit inside diameter must be 138% of the widest part of the cable. Not least, this makes it much easier to pull the wires through, since the individual wires are quite flexible. Otherwise if you're going to use conduit, do that.īut in conduit, you use individual wires - not a cable. If you're going to direct-bury cable, do that. Definitely get a huge panel with lots of spaces, and if that means the "main breaker" or busing is much larger than your feed, that doesn't matter. Calculating 3% on breaker trip is just throwing away money.Īnd by the way, there's a pattern where people who a) do that and b) also use copper wire without even thinking about aluminum, also c) buy too small a subpanel, and run out of spaces later. Indeed in Canada, where they require "nanny breakers" to keep your voltage drop below 3%, they only require that based on a) actual load or if not known, b) 80%. Heck no! If your breaker is 50A, the maximum current you're even allowed to plan for is 80% of that, or 40A. They make it sound like if your breaker is 50A, you need to calculate for 50A voltage drop. But it's probably unnecessary.Įven then, the calcs lie. If you want to keep the load a secret, by all means, we'll cheerfully "spend your money" lol. What NEC admonishes is try to avoid more than 8% cumulatively on all segments from the meter to the final load, but even that is situational to what the load actually is. And NEC even says so it's an informational note that advises 3% is an ideal to design toward if money is no object. Notice they also default to copper :)ģ% isn't that important. That's just the wire size calculators trying to upsell you on wire.
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