Author Topic: NO POWER  (Read 4288 times)

Offline ieezitin

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« on: October 28, 2017, 04:52:30 PM »

The power supply to my 110v well pump is set up by the pictures supplied.

My problem is when my pump is activated by the pressure switch calling for the pump to come on the motor just Humm's. I have checked the outlet for voltage and it shows 124 volts, the same circuit can run a light bulb but will not power high amp drawing motors, i have a portable air compressor which i have plugged in the same circuit and it does the same thing as the well pump it Humms.

In the juction box 1 picture it shows coming from the breaker my house supply (110v each) and where the well pump box is being supplied which i ran two 100v legs to it. My house has power and have no problems yet this goes through the same breaker as the well pump supply and i have problems with it.

I have an 8KW diesel generator and when i plug the well pump in it fires away and runs like a champ also the pump is brand new.

I am truly perplexed any advice?

Thanks   Anthony.
If you cant fix it, get another hobby.

Offline seadog

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« Reply #1 on: October 28, 2017, 05:04:44 PM »
Have you checked the voltage at the pump when it's powered? IT sounds like a high resistance joint. The condition of the main breaker doesn't look that good.

Offline PK

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« Reply #2 on: October 28, 2017, 05:08:51 PM »
Is it a single phase motor? If so, check the start capacitor. 
it's also worth checking that you can turn the impeller by hand.  Pumps have a tendency to get clocked with debris.

Offline ieezitin

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« Reply #3 on: October 28, 2017, 05:55:11 PM »

Its a brand new pump and it works fine when i use the generator, also the air compressor fails on the same circuit.


The voltage drops when the pump is trying to start, your right this breaker & box set-up is 30 years old its not in good shape. I may just replace the whole thing with new, but its nice to see what other people think this problem is especially people who know more than I on such matters.

Thank you both for your replies.


If you cant fix it, get another hobby.

Offline AdeV

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« Reply #4 on: October 28, 2017, 06:28:09 PM »
Is the genny supplying power over the same wires as the house circuit (disconnected obviously!!), or directly?

When the house circuit is trying to start the pump, do the wires get warm? (WARNING! Testing this may be hazardous to health - make sure you grab hold of a bit of wire with good insulation!!)

It's possible you've got a corroded or rough connection from the house to the pump - this, being high resistance, will get toasty hot; but it'll also sap the power, presumably to the point where the pump can't get started.

Without further info, I'd diagnose a rewire...
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Offline picclock

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« Reply #5 on: October 30, 2017, 06:51:34 AM »
Just my two penneth. The cable diameter to the pump does not look that large. When pumps start they need a large surge current. I suspect thicker cable or run another cable in parallel to increase the start current capability.

A quick trick to prove it, if your feeling brave, is to connect the live from the pump to a changeover switch, and once its running from the generator switch it over to regular mains. Not for the fainthearted as there will be no phase correction.

Alternately just get some cable or an extension lead and double up the connection.

I had a similar problem with a 13A compressor which refused to start even though wired with 35Amp cable a couple of hundred feet away. Doubling the cable sorted it, though it was a puzzle at the time.

Best regards (and good luck)

Engaged in the art of turning large pieces of useful material into ever smaller pieces of (s)crap. (Ferndown, Dorset)


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« Reply #6 on: October 31, 2017, 03:54:35 PM »
Is the house equipped with a 3-phase power ?
If this is the case then this might be a broken zero line as well. If this is the case You should fix it a.s.a.p. as this failure has a tendency to fry "unrelated" devices like laptop charger etc.
To test for this failure just switch on some light and if it turns BRIGHTER when the pump is "humming" then it might be the zero wire.

Edit: Actually not a 3-phase setup. Nevertheless the neutral wire could still be the culprit. It may well be that the neutral is broke and You get the "neutral" using the shield ground. I can see that these two are connected in the pump box.

Is the electricity in the house all OK when the pump is "humming" ?

Offline naffsharpe (Nathan)

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« Reply #7 on: December 18, 2017, 01:17:43 PM »
Sounds like a neutral (uk) /0 volts (elsewhere) to me. Probably a corroded terminal or cable end causing high resistance. If it's a capacitor start/run pump check/replace the capacitor. Check the motor windings if cap start or run. As you do not show the pump having 4 leads from the breaker (ground/main/aux/cap) you may have a capacitor IN the pump. Check manufacturers specs or give the pump details and I'll check it out, it's what I do for a living. Nathan.