Amperage Draw ...heater and pump

[captainron19]

Trying to figure out the total draw on the circuit for my pool to see if I can put a small fridge outside ..... Cant seems to find the amp draw on my pump or heater. Right now they are both on a 30 amp circuit.

The pump label only shows.... Model UST1152 Volt 115/230 RPM 3450 The amp draw section of the label is blank but there is a section for max amp that reads 18 (just seems like the 18 is awful high) I believe it is a 1.5 HP

My heater is a Hayward Gas H250. I believe the amp draw on this is minimal since the only electrics are for the control panel and the electronic ignition.

If anyone can offer any help it would be appreciated.

[Sean OBrien]

Is the circuit currently 115 or 230 (or your preferred interpretation there of of residential voltage levels)?

If it is currently setup for the lower voltage, the 18 amps will be about right for the startup current. It will drop some once the motor gets going. If it is currently wired for the higher voltage rating, the current draw will be down around 6-8 amps depending on the efficiency of the motor and a few other factors. A quick search popped up this file:

http://www.lockewell.com/pdf/aosmith/aosmith-UST.pdf

According to that, the 230 volt current draw is 18.6 on the 115 volt side of things and 9.3 amps on the 230 volt side of things. The H250 manual can be found here:

http://www.hayward-pool.com/pdf/manuals/Manual285.pdf

It lists the electrical requirements for you as well on page 15, and lists it at 0.3 amps.

The other issue of course is that if your 30 amp circuit is 230 volt right now, that won't be much help with hooking up a refrigerator which will likely be 115 volt. You can do it, just the last I checked it was a code violation (used to see people tap off from the legs of 230 volt circuits fairly often to add outlets in kitchens and the like). Since you say it is a 30 amps though, chances are better than not that it is a 230 volt circuit. 115 can be run at that high of current, but it is very rare for it to be done in that manner.

That means you will likely need to run a 115 volt circuit out to where you want the fridge. GFCIs and all of that as well - give your self an additional outlet for miscellaneous stuff like a radio. If you really don't want to run a new circuit, take a look at your lighting circuit. If you have one, pretty good chance that it is 115.

[spica]

Try using your service utility meter. The electronic ones usually sends a pulse every 1Wh.

Let me give you an example with an electronic service meter (how I measured my two speed pump usage):
Everything off (baseline): 8pulses in 84seconds or 5.714pulses/second or 342.8W
pump low: 11pulses in 73seconds = 9.041 pulses/second difference is 3.327pulses/second or 200W
pump hi: 30pulses in 78seconds = 23.08 pulses/second diff 17.37pulses/second or 1042W

Here you can also see that two speed pump uses 1/4 or less of the energy on low (half of full speed).

To get an amperage reading, you can divide the power by the voltage, i.e. 1024W/230V = 4.45A. This assumes the power factor is one which is not always true, but should be close for motors, but it doesn't really matter because your utility company charges you for the energy used, not the current.

When you do your readings, make sure anything else in your house will not be switched on/off (like fridges), since it will affect the accuracy of your readings.

[Gregg]

Not sure of your local regulations, but here it is a code violation to have ANY other electrical device on the same breaker/circuit as your pool pump. The requirement is in fact a twist lock plug so only one outlet is in the box.

I'm an electrical engineer so I can help you with the current draw part...

The motor can be wired for 120 or 240 volts. 115/230 is just a old fashion term, but pretty much all of north america is over 240 volts now for residential. The motor max amps is the cold starting amps required to turn the motor from a dead stop, this can be anywhere from 1.5-2 times the normal current. That being said, you have to size circuits based on that value so the fact it will draw less current means nothing.

This motor at normal 120 volts will draw a maximum of 17.25 amps. If it is wired for 240 volts, then the maximum current will be 8.6 amps.

The circuit breaker is WAY over sized for this motor, did a licensed electrician put this in?

The circuit breaker for this motor should have been 20 amps, wired with 12 gauge wire, and again it should be in a water tight electrical box with a twist lock plug that only allows for 1 plug to be on the circuit.

At my home for example, I have two separate feeds, one 20 amp circuit feeding my pool and another 20 amp circuit feeding a outdoor outlet that sits under my deck for anything I need to plug in on the deck.

I wouldn't recommend doing this any other way.

Regards.

[CarlD]

Gregg, we have the same code in my part of NJ. We have additional requirements about the max length of the pump cord as well, plus there must be an addition GFI 120v outlet within a certain distance of the pool.

Carl