Lever Edge electrical switches & outlets

Everyone knows there can be many sockets on either 15 or 20 amp duplex circuits. Two 10 amp loads can be plugged into a single 15 amp duplex outlet. The circuit breaker sees no difference. The invitation is the same to do so. Then add an extension cord with three plugs on it and get three more invitations. Makes no sense to me, that having a 20 amp outlet on a 15 amp circuit poses any issue. But does make sense to me a 15 outlet on a 20 could.

 

As suggested conventional wisdom, "common sense" or whatever is sometimes wrong. Typical 20 amp appliance or garage loads are not series connected to other outlets. Multiple continuous loads will trip a 15 amp breaker if they reach 19-20 amps. Just not right away.

Making an argument the electrical code and design engineering "does not make sense" is unlikely to hold up in court.

 

You haven’t said why the code says it’s ok to have several 15 amp sockets on one 15 amp circuit. Kitchens usually have two outlets on a 20 amp circuit. Each outlet has two sockets 20 amps each, so four invitations to overload. Every 15 or 20 amp gfci has the bottom connection to go to the next outlet, protecting both, or more than two.

I have an electric kettle and air fryer on one 20 amp outlet and circuit in the kitchen, since there are two plugs inviting me on a duplex outlet. They each draw about 13-14 amps. I only use one at a time, maybe I’ll put em both on and wait to see how long it takes to throw the breaker. The kettle heats water fast maybe no time to BURN THE HOUSE DOWN. So you are always safe as long as breaker and wire is correct, up to a certain wire length. I suspect at 28 amps the wire is going to get pretty hot. It’s close to the panel though. 15 amp duplex outlet is not rated for this.
A very close neighbor had a house fire in the middle of the night recently. I heard all the fire trucks, and wondered what kind of tree fell that gas saws were running full speed so long. I am not sure what wall they made an opening on or why. Eventually everyone will talk about it to get the scoop. I suspect electrical.

 

You can get the National Electrical Code (or find it at your friendly library) in the "Handbook" edition, which also includes explanatory commentary and rationales for why various decisions got made the way they did. The commentary portions are in a different typeface/color to make clear they aren't part of the enforceable Code, but they are interesting reading. If you're after those kinds of "why the code says" questions, that's where to go. The code editors have already done that work so your fellow PriusChatters don't have to.

 

There are also code requirements that limit how many wires/connections can be present in what size of junction or outlet box, and the limits are lower for thicker wires. I think it's both a matter of how much heat might be dissipated and also just, mechanically, being sure a box has enough volume to bend in all the wires without damaging them.

So, the "do I use 14AWG or 12AWG?" question involves more than just the cost of the wire.

 

Thermal trip behavior in circuit breakers always blow people's minds.

I don't have a single 14 gauge Romex in my house and it has metal conduit between the main and sub panels. Perhaps a result of too much past industrial work where codes are enforced and safety is important.

 

An extra $800 for one house, on the assumption that all the others are still being wired with 14AWG.

If all of them got wired with 12AWG there would be quite the spike in copper prices in the short term, and probably something higher than an $800 per house increase even after it settled past the transient demand spike.

There are still plenty of jobs (circuits) that can be safely performed for a lifetime with a 15A rating.

And lastly, a philosophical point- "$800 more" may not sound like much of an increase to current homeowners, but it's terribly tone-deaf at a time when housing costs are a major point of social friction.

 

The last time copper price speculation caused builders to "economize" was in the 70's. Aluminum wiring replaced copper in residential spec homes. It was "affordable" but caused a huge number of house fires when homeowners and handymen connected outlets not rated for aluminum and did not realize screw torque had become an essential requirement.

Today, 20 amp receptacles on a 15 amp circuit are less of a problem. Primarily because houses and apartments burned down and copper in residential returned regardless of its cost.

 

Certainly something to be said for maintaining the stability of a rules-based system.