Re: smart plugs???

On Sat, 1/18/2025 10:12 AM, Lars Poulsen wrote:

On Fri, 17 Jan 2025 16:48:03 +0000, Mike Scott wrote:

... I'm looking at probably 3kW at 240V to run a heater.
>
The power level is just a bit outside my comfort zone for home
construction ...

 
On 2025-01-18, Lawrence D'Oliveiro <ldo@nz.invalid> wrote:

I should say it is. It’s well beyond the rating for a typical household
outlet. Whatever it is, I imagine you’re going to need professional
electrician help to set it up.

 
If I remember correctly,
 
US home outlets are 120V 15A. So 1800W max.
EU home outlets are 230V 10A, so 2300W max.
UK home outlets are 230V 27A, so 6.2kW max.
 
This is why electric tea kettles work so well in the UK.
And if I remember, there is a fuse in the PLUG, so an appliance can
have a cord with a smaller fuse if it doesn't need the full power.
 
This is why the UK plugs are so massively huge.
 
But even in the US, a 20A outlet is not unusual. It does require a
heavier wire gauge in the walls. And 240V with amperages from 10A
to 50A is common for washing machines, laundry dryers, electric
stoves and EV chargers. Unfortunately, the plugs allowed for them
are a motley collection of incompatible versions. I wish they would
allow the EU Schuko for 10A, and the UK socket for up to 30A.

Tsk. North American homes have two voltages within the house.
It is a center tapped 230V system. If you take the center tap
and one hot, that's 115V. If you measure between the two hot leads,
that is 230V.

         --- hot1     \___ bedroom1       The low power outlets are
         --- neutral  /                   balanced across the two sides
                                          of the center tap. This helps
         --- hot2     \___ bedroom2       balance the loads across the
         --- neutral  /                   pole transformer. Since at least
                                          three homes run off one pole can,
         --- hot1     \___ bedroom3       the balancing continues on neighbour
         --- neutral  /                   homes.

         --- hot2     \___ bedroom5       115V wall outlet
         --- neutral  /

         --- hot1     \
         --- neutral   \___ 230V          NEMA 14-50R wall outlet (behind stove, behind dryer)
         --- hot2      /
         --- SGND                         230V power is hard wired to central AC or BEV chargers (if present)

https://www.amazon.ca/Charging-Receptacle-Designed-specifically-Applications/dp/B0CS8FFC1W

     hot1 neutral hot2   safety-ground

https://www.amazon.ca/Leviton-279-Receptacle-Industrial-Grounding/dp/B00009W3AA

     NEMA 14-50R

Operated at 80% derating, the NEMA likely supports 40A loads (at 230V).

I went downstairs and checked.

I have a 230V 30A quad position breaker for one load (four hole outlet on wall).
I have a 230V 40A quad position breaker for the central air (hard wired) [compressor hard start].

I have a 230V 20A dual position breaker in hand, for a planned electric water heater.
                  (4.6kW rating, for a 3.5kW water heater on an electrical system with too high a voltage)

I'm on the edge of town, with rural quality wiring in an urban setting.

The measured voltage is 244V on the 230V circuit. Which means
for any sort of electric fire (the clothes dryer), the element
runs warmer than it should.

I think we deserve something a little more generous than
a piddly 1800W rating. I checked the nameplate on the clothes dryer,
and it is 230V 24A and the plate recommends a 30A breaker,
and the 230V 30A quad is provided for that purpose. And since
my mains is actually 244VAC, I expect I'm drawing a bit more
than the 24A number. Breaker doesn't trip in any case. The only
breakers I've had trip, are the 15A bedroom ones.

The air conditioner, doesn't draw anywhere near the breaker rating.
It's only a two ton. The original air conditioner took a bit to start.

I would think a 7kW rating would be fair, because I don't have
any copies of code to argue otherwise. With the panel size,
there may be a diversity limit on drawing too many amps for
a single load, and I think the quad position is as wide as
they're allowed to get.

One brother-in-law, has three 100A service panels in the house.
Two panels for the main house, one panel for the granny flat.
I don't know exactly how many smart meters it takes to measure that :-)
The house is "full of kids", so it's not hard to see where the
power goes. It goes everywhere. Another brother-in-law, runs
a large solar panel setup, so there are likely a few amps going
in the reverse direction there (in summer, when it is sunny).
I don't rate very highly, with my single 100A panel.

  Paul