Ihave a 200 amp electrical panel. I am thinking about upgrading my hot
tub/spa, by replacing the old guts of it with a new control center and
new heater, pump, etc etc. The only thing that will remain is shell
My current equipment is 110v based and I want to put in 220v
equipment. Obviously it will run higher amps due to the much more
My question is, how do I know if my panel is adequate and that I do not
exceed the amp limitations? What is the relevant part of the NEC that
Ain;t the max for residential 200A? For what it's worth, I've been running
100A with a spa as well without problems.
Anyway, there's some limit as to how much you can potentially overload (ie,
if you ran around and turned every circuit on at peak capacity), but I do
not know it. Maybe someone else does. I would not worry about it.
The only two other high current appliances that I have at home is
electric kitchen range/stove, and A/C. It is also 220v based. The rest
is usual bullshit, lighting, furnace, various TVs etc.
I guess I could add up the amp rating of the stove circuit breaker,
the A/C circuit breaker, the proposed hot tub, and then add 30 amps of
fudge factor. Would that be a very invalid approach?
Hot Tub 50A
======= ===Total 160A
Since this 160A total is comfortably below 200A, I can safely add a 50A
hot tub, right?
If you use 50 amps at 110V and the new system is 50% higher demand (75
amps at 110V) and you switch to 220V that 75 amps drops to 37.5 amps.
37.5 amps at 220v = 8250 watts
75.0 amps at 110v = 8250 watts.
The way hot tub heaters work is that they are resistors with a given
resistance. So, if they produce X amps at 110 volts, they would
produce 2X amps at 220 volts, due to Ohm's law.
A typical 220v hot tub heater is about 10 kilowatts. Or about 45 amps.
Actually, 220v equipment is typically lower amperage. Power level (watts)
is volts * amps, so at a given level if you double the volts, you halve the
amps. One advantage of 220v equipment is that you can use smaller wires, or
get less voltage drop on the same size wires as used in 110 circuits.
Also, in your other post you listed the current loads of some of your
appliances. Those are going to be peak loads and not constant, and probably
have a safety margin built in. The "fudge" (fridge?) is only going to hit
it's max for a second or two at startup, and probably isn't going to pull
30A even then. Your stove's not going to be using 30A, unless you're
running all the burners and oven on high at the same time..
There's web sites around that have info on calculating your load, but 200A
is probably enough unless you have a bunch of high power stuff (welder,
Just my $1.23 (2 cents adjusted for inflation...)
From the equipment you've listed, I think you have plenty of power. A 200A
service can meet just
about anyone's needs unless they have a mansion or electric heat. If your hot
tub is 50A now (at
120V), I don't believe it will be much more later. I've never seen a hot tub
that required anything
larger than a 60A double pole (240V) breaker, although I'm sure they exist.
You can go here to learn how to do a full up load calculation, but it is rather
posted the easier method, but even it confuses people.
Not really. 50A 220V is a balanced load. 50A 110V is unbalanced, and it
depends on what offsets it on the other phase (phase is not really the
right terminology. "Leg" perhaps? Or "tap"?).
I don't think I've ever seen a 50A one-pole breaker.
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