If you run a 20 amp circuit (12/2) with shared lights AND receptacles, can you use a 15amp switches? Its my understanding that the switch is rated for the load its carrying (lights), but what about the load of the whole circuit? Lets say you have a room on one 20 amp circuit supplying outlets(15amp rec) and lights(15amp switch)you plug in a vacuum cleaner, have mini fridge running, and a fan plus lights, you pull more than 15 amps on the circuit. The breaker won't flip, but will the light switches rated for 15amp be ok?
Electrical – 15amp switch load clarification
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Related Solutions
There's no problem with anything you've suggested. You can use a 15 ampere breaker to protect 14 AWG copper conductors, without a problem. If you feel that 15 amperes is not enough for the receptacles, there is no problem installing 12 AWG wire with a 20 ampere breaker. It's completely up to you what you think is best. If the cost difference is not prohibitive, it may be worth installing #12 on a 20A breaker. Especially if you think you might plug in multiple higher load items at the same time (George Foreman and electric mower for example), or may consider adding additional receptacles in the future.
There is also no problem using a junction box to provide power to different devices. As long as the box is properly installed, accessible, sized appropriately, and adequately sealed.
Nothing in electrical code says that lights and receptacles cannot be on the same circuit. It's more of a guideline than a rule. The general idea is that if the vacuum trips the breaker, you don't want to be left standing in the dark.
The only problem I see, is with the GFCI receptacles in your drawing. You will not need two GFCI receptacles. You'll simply feed the second receptacle, from the load side of the GFCI receptacle. When wired this way, the GFCI receptacle provides protection to the downstream receptacle.
To answer your questions in turn:
Yes, this is A-OK. The subpanel amp rating is simply a maximum rating, and it's better to have the extra slots and robustness of say a 125A panel vs a 50A one. (Very small panels tend to be awkwardly laid out, too -- yours, fortunately, doesn't suffer from that infelicity, but that's only one reason to get a 12, 16, or 20 slot one instead of the 4 slot one you have.)
As long as the load on the feeder does not exceed 30A, you're golden. Use the 3VA/square foot residential Code rule when determining how much actual power is drawn by the general lighting circuits, while I'd borrow the 1500VA/circuit rule from kitchen small appliance circuits for determining how much power the shop circuit uses for load calculation purposes.
The feeder breaker in the upstream subpanel is the disconnecting means for the downstream subpanel in the case of an indoor subpanel like yours. If you were using a main-breaker panel, you could retain the existing main breaker as an extra disconnecting means, but in a main-lug panel like yours, there's no need to add a disconnecting means that isn't required by the NEC.
Yes, since this is a subpanel, the neutral bar needs to be isolated. You can remove the bonding strap and screw and chuck them in the trash. Also, don't forget to get a ground bar kit so that you have a place to hook up grounding wires!
No, it doesn't -- leg balance in split-phase systems is generally taken care of by the way the panelboard's arranged. You have to install breakers in a pathological fashion (who the heck would skip every other slot in a panel fed with 240V split-phase?!) in order to get a severe unbalance, as the busbars are arranged so adjacent tabs are on opposite legs in most panels. In the case of your panel -- what you propose (i.e. putting two breakers in one section and the other two in the other) is alright as the inner two tabs are on one leg and the outer two are on the other.
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Best Answer
Using 15A light switches to switch <15A on a 20A branch circuit is OK, unless you're switching receptacles!
As it turns out, NEC 404.14(A) permits the use of a snap switch (general light switch) to control any hardwired, non-motor load up to its rating, or motor loads under specific conditions (informational notes omitted):
Note, though, this doesn't hold true when you're switching receptacles, as someone could plug say, a space heater into the receptacle(s) and exceed the rating of the switch as a result (informational note omitted again):
The reason why is in your hypothetical case, the wall switches are not in the path of the current the vacuum draws, basically. (Keep in mind that current flows in loops and that loads connected are in parallel.)