Do I have enough power for pumps, swg, heater?

kevreh · Jun 19, 2009

I have a 15amp breaker for my:

- 1 HP pump, 7.5 amps
- Heater (gas, electric starter, amps are negligible)
- SWG, 1 amp
- 3/4 Booster, 6.4 amps (NEW)

These are all at 240. The pump ratings are MAX. I'm guessing thats what they need when starting.

Question.... by adding the booster pump this brings my MAX total to 15 amps, am I getting too close to my maximum for the breaker? Or, since the booster doesn't start the same time as the main pump will their theoretical maximums never happen at the same time?

For what its worth, theres another 15 amp GFI dedicated to my pool light. Could I tap that? Not sure what it needs amp wise.

Running another line to the sub box would be a major PIA at this point so I hope I can make do with what I've got :? .

TIA,
Kevin

Brad S · Jun 20, 2009

Is your sub panel out by your pool equipment pad? Garage? How many amps do you have feeding your sub panel off the main? Give me a better idea of your set up and i can tell you what you need? Is your pump plugged into a 240 outlet?

kevreh · Jun 23, 2009

Thanks for the reply, just saw this reply today.

- Yes, subpanel is next to equipment pad.
- Sorry, forgot to mention that the subpanel *had* two 15amp breakers on it (before Saturday, see below). The 2 breakers from the main panel are each rated at 20 amps.
- The pump and SWG are both wired for 240.

Had an electrician out on Saturday to get his take. What I ended up doing:

- Put the new booster pump on a new 15amp 240v breaker (pump uses 12.8amps MAX)
- Kept the current 15amp (MAX) pump, SWG (<1amp) on the second 15amp 240v breaker.
- Kept pool light (~3amps) on its own 15amp breaker.

So of the 40amp subpanel total capacity I'm using a total of 33 amps, which is never really reached since pumps consume more when starting.

So, I think I'm set as everythings working fine. Let me know if you have any thoughts on this setup.

Kevin

Brad S · Jun 23, 2009

That sounds about right. 40 amps is plenty out there for what you have. thats 9600 watts capacity (amps x volts). The way you figure power need is to add up the watts used by each piece and see how that compares to the total watts at the panel. A 200 amp residential service will power 48,000 watts (really about 45,000) before it trips. More than enough for a 3000 sq ft house with a pool, 2 A/C units, oven, dryer, pool equipment, even a pool heat pump.

aaronp · Jun 25, 2009

kevreh said:
Or, since the booster doesn't start the same time as the main pump will their theoretical maximums never happen at the same time?

I think that you and the electrician are on the right track now, but just wanted to throw out a question for you...
What happens when everything is running and the power goes out for a minute or two? (long enough for the motors to spin down)
When the power comes back on, that would be your worst case scenario...

Your old system may have had problems, I think the new wiring scheme will handle it just fine.

kevreh · Jun 25, 2009

Thats a really good point. Guess I could simulate a power outage by switching off power to the circuit at the main breaker then turning it on. I could see it being a nuicense since we have brownouts a few times throughout the summer.

Just read your signature....for a foreclosure house it sounds like you really came into a nice setup. Even if it was a swamp at first. :-D

Thanks....

Brad S · Jun 25, 2009

9600 watts will handle it, no problem. Even if everything comes on at the same time.

kevreh · Jun 25, 2009

Just to clarify, don't I have only 4800 watts supplied to my subpanel since its sending 2-20amp 120volt lines to the subpanel (2x20x120= 4800watts).

Just checking.

Kevin

Brad S · Jun 25, 2009

I guess i dont understand your set up then. You said you had 240 volts at the subpanel someway so that you could run a 240 volt pump. That would mean the line coming from the main comes off a 40 amp dipole breaker (2 hots, a common, and ground). That would then tie into the subpanel, giving you 240 volts at 40 amps (9600 watts) to work with. You now have 9600 watts of power to distribute amongst several breakers for different circiuts. Thats really the proper way to wire this up.

It sounds like you have 2 lines coming from 2 20 amp breakers at 120 volts from the main run out to your subpanel. How are you getting 240 out of that? If each of the 2 20 amp coming from the main are on opposite phases, then you could have 240. But, i still dont get the set up. You say you have a 15 amp breaker supplying 240, but that would mean its a dipole and you would have to one leg from each of the 20 amp circuits from the panel. Not sure why the electrician just didnt wire it up correctly for you.

i think i know how its wired, and its not really correct. If you say your "tapping" of a 120 volt 15 amp for the pool light, thats kinda dangerous. I'd wire it up like a regualr subpanel at 240 volts off the main with a 40 amp dipole.