Power requirement/draw for an SWG

[Amontilado]

Folks,

I would like to install an SWG with my setup, eventually, but am concerned that I may not have enough available power with the old setup that I inherited. How much power does and SWG draw. I have available 10Gauge lines/30amp breaker running from the main panel to the "pool shed" sub-panel approximately 80ft downstream. The Superpump I have wired as 240V to better spread the current load across the wires. Any thoughts?

Also, anyone have a good source for a 2-pole GFCI breaker. What I inherited is a GE model, and has become difficult to find locally, with no alternatives.


Steve

 

[bk406]

Is the super pump all you have on that 30 amp subpanel? What do you have on the GFCI breaker now? What type/brand of SWCG do you have?

In general, they dont pull that many watts. Maybe 250-300. On that 30 amp subpanel, you have 7200 watts to work with (~6500 after de-rate) so you should be more than fine.

 

[TripleB4me]

An IC40 pulls 220 Watts.

 

[mas985]

It depends on the SWG but mine uses less than 250 watts.

 

[Amontilado]

Due to the length of the wire run, there is 10gauge running from the main breaker box in the house, with a 30 amp breaker to the sub-panel in the pool shed. The 3/4 hp pump itself runs off a 20amp 2-pole GFCI breaker. Due to the length of the wire run(but not sitting down and doing the calculations), I feel that having 20amps max to run the pump and SWG is a good estimate. With the pump wired as 240v, I believe that the draw is about 8-9 amps max per hot wire(the manual says a 10amp breaker is minimum for a 3/4 horsepower motor). Let see, 250 watts at 230 volts equates to about 1.1 amps rounding up, so looks like I would have enough amps to run and SWG (up-rounded 10 amp and up rounded 2 amps equals 12 amps)

I haven't invested in an SWG yet, with this being the research stage. No use going out and buying one, then finding out the setup I inherited can't handle it, or worse, cause problems or be a safety hazard.


Steve

 

[bk406]

You have plenty of power, but dont get overly caught up in the "amps thing". The breaker size is just based on how much current draw can go through the breaker before it trips. For a 20 amp breaker, its going to be a little less than 20, but thats not really relevent here. When you need to figure out how much power you have at a given location, you need to look at watts, not amps. As i posted before, you have ~6800-7000 watts at that subpanel. A 20 amp breaker is fine for your 3/4 HP pump. You could put in a completely different circuit for a SWCG on a 15 amp breaker, and another 15 amp breaker for an outside plug, and another breaker for a pool light (this is just an example). If you add this up, its 50 amps, but thats not how it works.
Look in your main panel. Add up all the breakers. It will be way over 200 amps. As i said, look at watts used in relationship to how many watts are at the panel.

Just a note. 10 gauge wire for a 30 amp breaker is fine, even over 80 feet. The voltage drop you would get on that is really negligable. Folks get way too hung up on, and worry about voltage drop over distance. While it is a concern, it not a big deal under ~150 feet and considering the small loads you have on that subpanel.

 

[Amontilado]

bk406,
A re-wiring of the pool shed is one of the things that I want take care of. What I inherited has some "creative engineering" through the years, and there are some thing that I need/want to take care of. I know that an SWG will help greatly taking care of the pool, with my working rotating shifts and not always able to give it the attention it needs/deserves. Now to convince the wife.....

Steve

 

[bk406]

Now to convince the wife.....

Steve

lol

 

[Lershac]

As long as its not one of those "break the bank" decisions... this is one of those things that I would do on my own initiative, and when she sees how much better things are with it... she will thank you. Its always easier (for me!) to ask forgiveness than to ask permission. I know! I am just a wuss!

 

[Amontilado]

I always try to respect her opinion, especially when it comes to money at that level. We have X dollars coming in, and frankly, sometimes it's too easy to say "buying this little thing won't hurt the budget". It's dealing with that dirty word that we all hate to mention, budget. But that is a conversation for a different time and place. I keep playin' the lottery, but that hasn't panned out


Steve

 

[mantion]

You have plenty of power, but dont get overly caught up in the "amps thing". The breaker size is just based on how much current draw can go through the breaker before it trips. For a 20 amp breaker, its going to be a little less than 20, but thats not really relevent here. When you need to figure out how much power you have at a given location, you need to look at watts, not amps. As i posted before, you have ~6800-7000 watts at that subpanel. A 20 amp breaker is fine for your 3/4 HP pump. You could put in a completely different circuit for a SWCG on a 15 amp breaker, and another 15 amp breaker for an outside plug, and another breaker for a pool light (this is just an example). If you add this up, its 50 amps, but thats not how it works.
Look in your main panel. Add up all the breakers. It will be way over 200 amps. As i said, look at watts used in relationship to how many watts are at the panel.

Just a note. 10 gauge wire for a 30 amp breaker is fine, even over 80 feet. The voltage drop you would get on that is really negligable. Folks get way too hung up on, and worry about voltage drop over distance. While it is a concern, it not a big deal under ~150 feet and considering the small loads you have on that subpanel.

Most breakers are not designed to trip at the rated amps. Look up the trip curve for your breaker and that is what you should expect, though every breaker will vary from spec. Typically they trip near instant in a short (or should) and then take longer at the rated amps. That is why you can run 2 air fryer and a toaster oven for a few minutes then it trips the breaker.