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Anon

Electrical question - 20A circuits

If a circuit has a 20A breaker, does every component (switch, receptacle, wires, etc) need to be 20A rated?

For example, I have a dedicated food disposal thingy on a dedicated 20A circuit. The wire, as far as I can tell, is 12 gauge. The outlet is a 20A outlet. But the switch is a 15A switch (marked 15A). Is this OK?

Another example, I have a dedicated 20A circuit for the garage door opener. Not sure what the wiring is; but the outlet is rated 15A. Is this OK?

UHF
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Not sure about the switch. The 15A outlet on a 20A circuit is fine.
tantivy4
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If the circuit is dedicated (has a single outlet), then the switch/outlet on that circuit should be rated for the capacity of the circuit (in this case 20 amps).

If the circuit is shared, then 15 amp devices are fine.

In all cases, the circuit breaker/fuse should be the proper rating for the minimum current rating of any circuit conductor.

In other words, if you have any 14awg wire in the circuit, then your circuit breaker can be no larger than 15 amps.

whizkid3
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said by help me spock :

If a circuit has a 20A breaker, does every component (switch, receptacle, wires, etc) need to be 20A rated?

But the switch is a 15A switch (marked 15A). Is this OK?
Yes & no.

15A duplex receptacles are rated for 20Amps. 15A single receptacles are 'pass-through' rated for 20 amps. They are called 15A receptacles, because their face only accepts 15 amp plugs. The rule is that you can not have only a single 15A receptacle on a 20A circuit. If this is your case, then you must replace the breaker with a 15A breaker.

Regarding switches, as long as their load does not exceed 15A you are fine. This will be the case with both the garbage disposal and the garage door opener, because they both have only 15A plugs.

Both of these situations generally require a single 15A receptacle. The garbage disposal, because it violates the NEC to have an 'accessable' receptacle below the kitchen counters, unless it is for a dedicated appliance. So if the disposal is plugged into a duplex receptacle, one of the receptacles is unused and accessable, violating the NEC. If it is a dedicated circuit, and you switch it out for a single 15A receptacle, then you can only have a 15A breaker. You can't switch it for a single 20A receptacle, without replacing the switch with a 20A switch.

Likewise, receptacles in the garage must be GFCI protected; unless they are for a dedicated appliance, like a garage door opener. Again, in this case, if it is not GFCI (not recommended), then you must have a single receptacle (unless you have two garage door openers plugged into a duplex outlet). If it is a single 15A receptacle, or you switch it out for one, and its on a dedicated circuit, then again, you can only use a 15A breaker. Depending where you live, the inspectors sometimes view this differently. Many will make you have a GFCI, regardless.

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Anon

Thanks for the replies so far...
said by whizkid3:

Both of these situations generally require a single 15A receptacle.

If it is a dedicated circuit, and you switch it out for a single 15A receptacle, then you can only have a 15A breaker. You can't switch it for a single 20A receptacle, without replacing the switch with a 20A switch.
A little clarification please...

Under the sink/kitchen counter, there is a 20A duplex receptacle; one for the food disposal thingy and the other for my dishwasher. Each of these are dedicated 20A circuits (They're controlled by a double pole 20A breaker). The wiring appears to be 12 gauge for both. But the wall switch for the food disposal thingy is 15A. So does this mean that the 15A switch should be replaced with a 20A switch?

Regarding my garage door opener... It's on a 20A dedicated circuit; but the receptacle is a 15A duplex one. The other receptacles in the garage are on a different 15A (GFCI) circuit that's shared with the bathroom and outdoor receptacles. So is this acceptable or does the receptacle for the garage door opener need to be 20A receptacle?

BTW, home was built in mid-80s.

Ken
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said by whizkid3:

The rule is that you can not have only a single 15A receptacle on a 20A circuit.
Do you know what the reasoning is behind that? I have often wondered why, since I don't see how it would pose any harm.

whizkid3
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said by Ken:

said by whizkid3:

The rule is that you can not have only a single 15A receptacle on a 20A circuit.
Do you know what the reasoning is behind that? I have often wondered why, since I don't see how it would pose any harm.
Honestly, I don't know what the reasoning would be to put a single 15A receptacle on a 20A circuit. The reasoning behind this rule, is probably that there is no reason to oversize the breaker, when a 15A breaker would interupt an overload faster, and hence be safer.
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either a single 15A outlet or a 15A outlet as part of a chain pose the same risk, so it does not make much sense to me either.
20A being drawn through a 15A outlet due to a fault, is still 20A no matter where it is.

whizkid3
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said by help me spock :

Under the sink/kitchen counter, there is a 20A duplex receptacle; one for the food disposal thingy and the other for my dishwasher. Each of these are dedicated 20A circuits (They're controlled by a double pole 20A breaker). But the wall switch for the food disposal thingy is 15A. So does this mean that the 15A switch should be replaced with a 20A switch?
I assume that what your saying is that you have a 'multi-wire' circuit, feeding a split-duplex receptacle. This qualifies as two dedicated circuits, each with a single outlet. You should make sure the duplex receptacle has 20 amp plug-faces with the 'T'-shaped slot(as shown in the picture above). Otherwise, you need to replace the breaker with a two-pole, 15A breaker. If the plug-faces are indeed as shown above, then yes, you must replace the switch with a 20A switch.
Regarding my garage door opener... It's on a 20A dedicated circuit; but the receptacle is a 15A duplex one.
Its OK to have a 15 duplex receptacle on a 20A circuit. However - and this is an issue that really would depend on an inspector and locale - if both receptacles are accessable, then both must be for dedicated fixed-in-place appliances, like a garage door opener. Otherwise, the receptacle must have GFCI protection, as it is in a garage. (Whether or not receptacles on the ceiling are accessable, also depends on the inspector.)
The other receptacles in the garage are on a different 15A (GFCI) circuit that's shared with the bathroom and outdoor receptacles.
Well, now bathrooms require GFCI protected receptacle(s) on a dedicated 20A circuit. This circuit can serve only the receptacles in multiple bathrooms, or it can serve everything in a single bathroom only. It can't be connected to other receptacles around the house.

I sounds like some of these issues (except the first one)may have been fine when the house was built; but would not be up to code today. It up to you whether you want your home 100% up to code, or not.
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said by vapochilled:

either a single 15A outlet or a 15A outlet as part of a chain pose the same risk.
No, not really. 15A receptacles are rated to handle 20 amps; they simply plug-faces that only accept 15 amp plugs. Having a 20 amp circuit to multiple 15 amp outlets reduces the chance you will overload the circuit when you have multiple appliances plugged in(vs. a 15 amp circuit). So it is indeed safer. When you have only a single receptacle, having a 20 amp breaker doesn't help you any. But, a 15 amp breaker will trip sooner on an overload. You really don't want to have a 15 amp appliance plugged in; it is drawing 19 amps (for example), and the breaker doesn't trip.

Obviously, yes, that can happen too if you have only a single appliance plugged in on a 20 amp circuit with multiple 15 amp receptacles. But this is much less likely to happen, than overloading the circuit when you have multiple appliances operating.

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Thanks whizkid3 for the detailed explanations... Your assumption/interpretation of my description was right on! I appreciate your time and patience in providing specific answers to my questions.

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NEC (electrical underwriter code/national) requires kitchen circuits rated for 20 amps. a 20 amp circuit means 20 amp disconnect (ground fault), #12 wire, appropriate sized device boxes and 20 amp devices (switches and receptacles). NEC code is typical for most areas (didn't notice your location) for insurance companies fire underwriting. if your contractor obtained necessary permits, an electrical rough and final inspection was completed. if job passed inspection, you should be OK.

whizkid3
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said by builderbob :

NEC (electrical underwriter code/national) requires kitchen circuits rated for 20 amps.
Yeah it does. But this is only for the two required small appliance circuits that cover the counter-top. The OP is talking about dedicated fixed-in-place appliance circuits. These are to be sized for the appliance. And to have a fixed-in-place appliance (except the fridge) on either of the two required small appliance circuits, would violate code. So...

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said by help me spock :

Thanks for the replies so far...
said by whizkid3:

Both of these situations generally require a single 15A receptacle.

If it is a dedicated circuit, and you switch it out for a single 15A receptacle, then you can only have a 15A breaker. You can't switch it for a single 20A receptacle, without replacing the switch with a 20A switch.
A little clarification please...

Under the sink/kitchen counter, there is a 20A duplex receptacle; one for the food disposal thingy and the other for my dishwasher. Each of these are dedicated 20A circuits (They're controlled by a double pole 20A breaker). The wiring appears to be 12 gauge for both. But the wall switch for the food disposal thingy is 15A. So does this mean that the 15A switch should be replaced with a 20A switch?

Regarding my garage door opener... It's on a 20A dedicated circuit; but the receptacle is a 15A duplex one. The other receptacles in the garage are on a different 15A (GFCI) circuit that's shared with the bathroom and outdoor receptacles. So is this acceptable or does the receptacle for the garage door opener need to be 20A receptacle?

BTW, home was built in mid-80s.
Technically yes you need a 20A switch but its a moot point because its going to be impossible for you to ever draw more than 15A through the outlet (at least there should be no device that draws more than 15A that fits in that receptacle)

Alot of NEC stuff can be taken more as "design advice" especially when trying to update old buildings. I'm not sure if it was NEC or local building code almost sure it was NEC but they specify how many outlets you should have on a certain wall, in a certain distance, etc. Yea you need that stuff to pass an inspection on a new building but how does that relate to safety (Yes I know avoiding the use of "dangerous" extension cords)? You aren't going to start adding outlets every 3ft on every wall on your house just be be NEC compliant.

whizkid3
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said by joako:

Technically yes you need a 20A switch but its a moot point because its going to be impossible for you to ever draw more than 15A through the outlet (at least there should be no device that draws more than 15A that fits in that receptacle)
Don't take this the wrong way, but you really don't get it. The 15A switch is fine, according to the NEC, for a single 15A outlet. Its the single 15A outlet, that is unnacceptable on a 20A circuit, according to the NEC.
Alot of NEC stuff can be taken more as "design advice" especially when trying to update old buildings.
I'm not sure what your opinion is based on. The NEC covers more than just design. It is a fire and building code, and is the law in all 50 states. It is not a just design handbook. None of the requirements we're discussing have changed in the code, for at least as long as I can remember, and that's a long time.
I'm not sure if it was NEC or local building code almost sure it was NEC but they specify how many outlets you should have on a certain wall, in a certain distance, etc. Yea you need that stuff to pass an inspection on a new building but how does that relate to safety (Yes I know avoiding the use of "dangerous" extension cords)? You aren't going to start adding outlets every 3ft on every wall on your house just be be NEC compliant.
Yeah, I wouldn't think so. In a residence, the NEC requires a receptacle only every 16 feet; 8 feet from doors. That really isn't extreme, if you ask me. How does it relate to safety? C'mon.