Weird Pool wiring problem

nsxtasy · 03-01-2012, 07:48 PM

Howdy. I bought a A O Smith a/c motor 3/4 hp on ebay which was new. Everything as described. I swaped the pool pump from my bad motor (bad bearings) to this one, I rewired it for 230V (came wired for 115V but can work with 230V), hooked it up, then nothing... No movement, noise, nothing... I checked that I'm getting 230V to the motor, but when connected I get 120V between white and copper, 120 V beetween black and copper but 0V between black and white (which are connected on 1 and 6 as the diagram shows), whereas when the motor is not connected I get 230V as I should. I'm thinking the capacitor might be bad. Any information you have sharing your experience would be helpful. thanks in advance

Ebay link from my purchase with pictures showing diagram and specs

http://cgi.ebay.com/ws/eBayISAPI.dll...#ht_2399wt_922

bob22 · 03-01-2012, 07:51 PM

Sounds like your white and black are being fed from the same bus bar. Check where the two-pole breaker is feeding them in the panel to make sure you are drawing each from different bus bars.

rrolleston · 03-01-2012, 08:07 PM

Sounds like a bad connection that is causing you to lose voltage when there is a load?

nsxtasy · 03-01-2012, 09:14 PM

The zero V reading is measured with the motor attached and power on but no load (no humming or anything like this). Would I still measure 230V (motor disconnected) if was indeed fed from same bus?

zappa · 03-01-2012, 09:19 PM

Quote:

Originally Posted by nsxtasy

The zero V reading is measured with the motor attached and power on but no load (no humming or anything like this). Would I still measure 230V (motor disconnected) if was indeed fed from same bus?

no...

zappa · 03-01-2012, 09:22 PM

What sort of device switches power to the motor?

mpoulton · 03-01-2012, 10:06 PM

Either both of your wires are fed from the same bus or one of the wires is not connected, which will cause the same symptoms. This could be a problem with a double-pole switch or contactor, or it could be a loose connection or wiring error. I must say though, swimming pool wiring is quite specialized and doing it right is extremely important for safety. This problem is quite basic, and it concerns me that you're working on pool wiring without the understanding needed to handle this sort of troubleshooting.

Edit: Having read 240V at the motor leads with no load connected, it's safe to say the wires on are the right busses. The only likely problem is a loose connection or bad switch/contactor.

rrolleston · 03-01-2012, 10:16 PM

Quote:

Originally Posted by mpoulton

Either both of your wires are fed from the same bus or one of the wires is not connected, which will cause the same symptoms. This could be a problem with a double-pole switch or contactor, or it could be a loose connection or wiring error. I must say though, swimming pool wiring is quite specialized and doing it right is extremely important for safety. This problem is quite basic, and it concerns me that you're working on pool wiring without the understanding needed to handle this sort of troubleshooting.

Don't pool's also require a GFCI? I know my parents pool stuff is on GFCI.

frenchelectrican · 03-01-2012, 11:07 PM

Quote:

Originally Posted by rrolleston

Don't pool's also require a GFCI? I know my parents pool stuff is on GFCI.

They do required it and it will be well stated in Art 680 IIRC that will cover pretty well.

BTW that do count for both 120 and 240 volts motours.

I have one pool I dealt with one of my customer they have triphase pump motour and it allready on the RCD ( GFCI ) per French Nomes ( French Codes )

Merci,
Marc

zappa · 03-02-2012, 05:28 AM

Quote:

Originally Posted by mpoulton

Either both of your wires are fed from the same bus or one of the wires is not connected, which will cause the same symptoms.

mpoulton....you have always impressed me with your knowledge and good advice on this forum, but you have left me scratching my head on this one. If you have 2 hots on the same bus how does one come up with a 240 volt reading, loaded or unloaded? Name: blink.gif
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Besides, the OP is replacing a motor with bad bearings in an obviously working system so what are the chances that he would go into the panel or anywhere else and switch wires around.

mpoulton · 03-02-2012, 06:09 AM

Quote:

Originally Posted by zappa

mpoulton....you have always impressed me with your knowledge and good advice on this forum, but you have left me scratching my head on this one. If you have 2 hots on the same bus how does one come up with a 240 volt reading, loaded or unloaded? Attachment 46829

Besides, the OP is replacing a motor with bad bearings in an obviously working system so what are the chances that he would go into the panel or anywhere else and switch wires around.

You're right. I didn't read carefully enough - I was assuming he hadn't actually measured 240V at the motor. The only explanation that's consistent with all his measurements is a very high resistance (defective) switch or loose connection.

zappa · 03-02-2012, 06:12 AM

Quote:

Originally Posted by nsxtasy

I'm thinking the capacitor might be bad.

The capacitor won't be your problem. I would start by checking whatever it is that switches power to the motor. With the motor hooked up and turned on meter across the input and output contacts of your switching device on each leg. If working properly you should see essentially zero volts. A high voltage reading would indicate that the contacts are not making a proper connection. But if the system was working before I'm a bit confused as to why this power problem would show up now.

Murphy?

edit... sorry mpoulton, I was writing when you posted. Yes, a loose connection anywhere in the system also.

J. V. · 03-02-2012, 11:50 AM

I would check to see if the motor has a switch inside the connection box that must be set for the voltage. OP. Whats the AO Smith model and serial number.

nsxtasy · 03-02-2012, 01:25 PM

Quote:

Originally Posted by zappa

What sort of device switches power to the motor?

It s à on/off outdoor switch with waterproof cover that uses 2 lines + copper line. Even when I'm measuring 0 V between lines at the motor, I'm measuring 230v at the switch when in Off position. Even when I'm measuring 0 V between lines , I'm still measuring 115V at between each line and copper wire.

nsxtasy · 03-02-2012, 01:30 PM

Quote:

Originally Posted by zappa

The capacitor won't be your problem. I would start by checking whatever it is that switches power to the motor. With the motor hooked up and turned on meter across the input and output contacts of your switching device on each leg. If working properly you should see essentially zero volts. A high voltage reading would indicate that the contacts are not making a proper connection. But if the system was working before I'm a bit confused as to why this power problem would show up now.

Murphy?

edit... sorry mpoulton, I was writing when you posted. Yes, a loose connection anywhere in the system also.

I am measuring between the 1 and 6 legs where black line and white line attach to the motor. This is Where I am measuring 0 V. So you're saying its normal?. So Why is the motor not spinning?