In a 6-space panel, "main breakers" are placed in regular breaker positions and backfeed. "6-space guy" got blindsided by needing a "main" breaker as a disconnect switch. You do need a "main breaker" (well, disconnect switch) at EACH subpanel So that means we're calculating your workshop run at 80A. Either calculate it on expected load, or on 80% of breaker trip since that is the max you're allowed to plan to load. Never calculate voltage drop on breaker trip. But let's say you actually need 80A, so you breaker for 100A. Now, if you actually needed 100A, you'd be required to breaker for 125% of that, or 125A obviously. "Nanny breakers" (downbreakering to a 60A to protect yourself from "voltage drop" ooga-booga) are not required in the USA or El NEC countries.įor the 100A run, you can't breaker the 2-2-2-4 at 100A, I'm sorry. Feel free to breaker those at 80A at the main, since that is allowed on 2-2-2-4 of any length (unless the length carries it into Canada, then no). The 2-2-2-4 Al is a perfectly fine wire size for the runs you have "60A". If I were paying for the panels - and I do pay for most of the panels I install - I would use a 12-space main-lug at the remote sites and a 30-space at the shop. A pizza? Skip it and enjoy an installation with expansion room. If it was hundreds of dollars of wire, sure. Everytime you change a panel you risk damaging wire - and then you're really in trouble. So $30 more (net) and a vastly superior panel with plenty of expansion room. I put the person into a 24-space panel with a main breaker and with $20 worth of bonus breakers, for $70. How many times are you going to replace panels? That person is painted into a corner and must now install an 8-space, and will need to go 12-space for the next thing. Can't use double-stuffs because 2020 NEC pretty much outlaws them. They wanted a hot tub, well that takes 2 spaces, and they're out of space. Just for one each 120V and 240V utility sockets, the person now has 1 space left. Boom 2 spaces gone that the person did not expect to lose. #1 guess what, you need a main disconnect. This one person thought the $20 6-space panel was a great bargain. And don't be chintzing out on panels anyway. Nope! That trick never works! But I'll come back to that. Their dream is that this local breaker will trip first, and save them a walk. Some people want the subpanel's local main breaker to be same size as the feed breaker. Is the panel running at redline? No, not nearly, it's well in its safety zone. Because that's decided by the feed breaker. That breaker is nothing but a local disconnect switch. The subpanel has its own "main" breaker of 200A. Your actual main panel has a 60A breaker feeding a 2-2-2-4. The "main breaker" in the subpanel is nothing but a disconnect switch. That's decided by the feed breaker in the main panel. The size of the subpanel does not decide the load. Even if you never plan to pull more than 60A, a 100A panel is better, and a 200A panel is better still. The fact that it's good for 112 mph, you see that as safety margin. Have you ever gone "My truck has never gone faster than 85 mph, therefore I can't use an HR rated tire"? Of course not. You're making the classic novice mistake.Įver bought tires? They come in different speed ratings.
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