Power Usage by Water Pumps

[luvrbus]

The actual draw depends on various factors such as head, hose diameter, distance, etc. Those figures are probably rated, meaning nominal operating specification.

I don't where they get the figures from most call for 15 amp switch on the 6.5 draw pumps.then about 1 in every 25 owners don't use a relay per instructions they wire direct and forget about it,most of those pumps draw a small amount of current when the power is on,  mine draw 15 milliamps ea when not running lol that is the phathom draw I look for some times for days   

[chessie4905]

The listed amps is probably at maximum  rated pressure developed.

[richard5933]

Due to the continuous current of DC, as opposed to alternating current, the wear and tear on switches can be higher than expected. There is more arcing than an AC circuit which pits and burns switch contacts.

I'm guessing the need for a higher rated switch is to help protect against premature failure, as water pumps are often switched while under load.

[luvrbus]

Due to the continuous current of DC, as opposed to alternating current, the wear and tear on switches can be higher than expected. There is more arcing than an AC circuit which pits and burns switch contacts.

I'm guessing the need for a higher rated switch is to help protect against premature failure, as water pumps are often switched while under load.

How does that affect a switch on a relayed circuit, my pumps are on a 30 amp relay for each pump ? I can see a 5 to 7 amp switch but not a 15 amp

[richard5933]

Sorry - didn't catch the part about the relay. The pump we're using (Shurflo 2088 series) only draws 5 amps per the label on the motor. They recommend a 15-amp slow blow fuse. I've just used a standard 15-amp and have had no problems.

Not sure why anything more than a 15-amp switch would be required. It would seem on the surface that a 5-amp switch would suffice, but apparently they concluded that the pump can draw more than the 5 amps, possibly when under heavy load or pushing up against a large head?

All that said, if you're using a 30-amp relay then I don't see any problems at all using a switch with a lower rating. It only has to be enough to activate the relay. The instructions that came with my pump made no reference to using a relay, although I can definitely see the advantage to doing so in the future.

[Oonrahnjay]

...  Not sure why anything more than a 15-amp switch would be required. It would seem on the surface that a 5-amp switch would suffice, but apparently they concluded that the pump can draw more than the 5 amps, possibly when under heavy load or pushing up against a large head? ...

       Excellent info, Richard, thanks.  Just a guess, but it would seem that a water pump is likely to draw a pretty substantial start-up surge.  That could be another factor.