Power Question

[Tyler]

00000000000000000000

[ship]

a bit of a hack way of doing the distro & civilian as it were way of defining it, but a maximum of 30A per leg of power. Three sets of outlets per leg at 30A. 60A total if both legs added together.


Realistically I would keep to 80% of that maximum loading and attempt to balance my load between the two phases as best possible.

Use all three receptacles @80% of 10A per receptacle per leg for a total of 6 receptacles at 8A each, or use two receptacles per leg @12A each for a total of four receptacles on both legs of power and don't use the extra receptacles...

[Malabaristo]

To me it sounds like they did it wrong:
I would interpret what they said as two 30 amp circuit breakers (or fuses) with three edison duplex outlets connected to each circuit. Edison outlets are only rated at either 15 or 20 amps depending on whether the blades are parallel, or if one of them is turned sideways. Having 15A or 20A outlets fed by a 30A breaker is not particularly safe or legal. It would be a good idea to have a qualified electrician take a look at this "distro" to make sure it meets code.

[ship]

Agreed sounds sketchy and the details could be for something proper or wrong, but if I remember the NEC correctly you can have a 30A breaker/fuse circuit if a few 20A receptacles fed by it in a way similar to having a 20A breaker feeding a few 15A outlets. I'm sure someone will verify that's the case yes if say wired by 10ga wire or other means ... but not really the proper way to do it as intended either. Thinking more likely some form of company switch that someone tapped for adding a few outlets to. If that's the case I'm unsure on it's code compliance in a general concept of the box should have been replaced and a sub panel with individual breakered outlets should have been installed.

Details of the power distro I'm on the fence about in being something sketchy to be concerned about or possibly ok but probably not due to sufficient circuit protection etc. short of specific details or seeing it. Wasn't going there in general, just stating the distribution concept in general but good point taken up on concern for safety.

[FMEng]

I believe that Ship is correct. The fuse size is to protect the wire feeding the receptacles, not the receptacles themselves (within reason). You can load any duplex plug up to 15 amps, for a total 24 amps (80% of 30 A) per leg.

[TimmyP1955]

I believe that the breaker or fuse must be no larger than the capacity of the lowest rated device on the line. So if 10 gauge wire (which is rated for 30A) feeds 15A duplexes, the circuit would have to be fused at 15 Amps, no matter the number of 15A duplexes.

[mrb]

having anything smaller than a 30a receptacle on a 30 amp circuit is not to code, nor is it safe. Here is an outline of what is allowed:

15a breaker - one or more 15a receptacles
20a breaker - single 20a receptacle
20a breaker - multiple 20a receptacles
20a breaker - multiple 15a receptacles

The circuit breaker is not just there to protect the wiring supplying the receptacle, is is also there to protect the device as well as what is plugged into it to some degree. You cannot supply a duplex 15a receptacle with a 30a breaker.

This is for reference only, consult applicable codes and hire a licensed professional or other qualified individual for all electrical work.

[SteveB]

Duplex receptacles are rated for either 15 amps or 20 amps, and the description you've been provided indicates a code violation.

The overcurrent protection must be of the same rating, or smaller, then any permanent device connected.

Doesn't matter how many devices - which in a residential application can be as many as 7 devices downstream (example I read was 7 receptacles in a living room on a 15 amp breaker). The breaker can not be of a higher rating then either the wire or the device.

SB

[mrb]

Originally Posted by SteveB

The overcurrent protection must be of the same rating, or smaller, then any permanent device connected.

SB

the exception to this is you can put multiple 15a receptacles on a 20a breaker, but not a single 15 on a 20a breaker. I dont remember if that applies to one duplex, or a single receptacle, i think its just a single receptacle.

[FMEng]

I stand corrected. MRB is quite correct.