Electrical Problem Diagnosis

            No, I can't really teach you how to diagnose every pool electrical problem. The best I can do is give you an idea of how this process works. So, I am going to go over my thinking and diagnostic process with 2 of the situations I came across this month:
1.) I had a customer with a Pool Light Out. Note: He just wanted a price on a bulb. I told him that while the chances were good that that was the only problem, the only way to be sure was for me to come out and check. I explained that while the bulb was the most likely possibility, there were others as well, including:
            a.) The bulb itself is out (Most Likely)
            b.) There is a short in the housing or the wire between the light fixture and the Grounded Light Box.
        c.) There is a short in the wire between the Grounded Box and the Switch.
            d.) The light switch is bad
            e.) The wire between the Switch and the GFCI is bad
            f.) The wire between the GFCI and the Panel/Sub Panel is bad
       g.) The breaker in the panel/sub panel for the pool light is bad
           h.) There is water in the light, because the gasket leaked, but there is no problem other than a leaky gasket, and once things are dried out he won't even need a bulb. 
            i.) Some combination of the above
        How it played out:
            a.) The most obvious is that the light bulb is burnt out. Yes, I could take it out of the wall of the pool, open up the housing, remove the bulb, and then check it with a continuity tester. OR, I could open up the Grounded Box, disconnect the white and black wire from the pool light cord, and check the continuity of the bulb without pulling it out of the wall or opening up the housing, by attaching the tester to those two wires. This tests the bulb, but also, with the wires disconnected, I can test the two wires that are supposed to carry current to the light as well. Simply reset the breaker, GFCI, turn on the switch, and see if we have current.
            b.)  After testing the continuity, something odd happened. I got an indeterminate reading. In other words, I didn't get full continuity, only partial, which is odd. Just to be sure, I attempted to reset the GFCI, Breakers, and turn on the switch as well to see if we had 120 volts at the disconnected feed wires. The GFCI would not reset.
            c.) We have multiple problems. Something with the pool light itself, and something with the GFCI, the Switch, or the wiring between them.
            d.) So I pulled the light out of the wall. There was water in it. The possibilities for the light are:
                I.) The gasket leaked (most likely)
                II.) The housing leaked (Next most likely)
                III.) There was a crack, nick, ... in the cord that allowed water to seep into the light. (Least Likely)
so ... I left the housing on the deck to dry out while I checked further into the GFCI.
                IV.) Additional problem ... the bulb socket had been wet so long that the glue around the bulb had softened, and the brass from the socket and the metal from the bulb, corroded together. Since the bulb was shot, I pulled it out in pieces, and used a needle nose pliers to pull out the remaining part of the bulb.
            e.) The GFCI problem was easy enough to find. I opened up the box holding the GFCI, disconnected the "Load" side wires and tried to reset the GFCI, and checked the Line wires for 120 volts. We had power to the GFCI, but it would not reset. Thus, we have a bad GFCI that needs replacing. But why the other problem, and are they related? Went to pick up a replacement bulb and a new GFCI.
            f.) A few days later,  I hooked up the new GFCI, sanded the socket for the bulb, installed the new bulb, hooked up all the wires again, and flipped the switch. Immediately the GFCI tripped. Problem still not solved. Shut off the switch, disconnected the light wires again. Reset the GFCI and flipped the switch. GFCI stayed on, and after checking, I found out we had 120 v. to the wires. Not a problem with the GFCI or the wiring. since the housing was dried out, the issue with the light. 
            g.)  The client was informed that a short in the housing or the cord of the light itself, resulted in frying the GFCI as well. A new light was pulled, and everything works as it should.
2.) Pool Motor Problem: Client called and said that the pool motor wasn't working.
            a.) The motor itself is bad.
            b.) The wiring between the motor and the switch is bad (Provided it was wired properly.)
            c.) The motor switch is bad.
            d.) The wiring between the switch and the time clock is bad. 
            e.) The time clock is bad.
            f.) The wiring between the time clock and the breakers is bad
            g.) The breakers are bad. 
    Note: The customer called after 5 pm, and the earliest I could get to it, when the customer was there was 2 days hence, between 5 and 5:30 pm. The customer asked if there was something he could check, and told me that the breakers were tripped and would not reset. Given the customers knowledge of electricity (Lineman for the electrical company), I told him that he could shut of the circuit breakers, find two similarly linked breakers of the same amperage, shut those off, disconnect the wires going to them, and from the pool motor, and switch them. If, when the different breakers now hooked up to the pool motor, are turned on, the breakers don't trip, and the motor runs, the breakers are bad, or weak, and they need to be replaced. If the items attached to the old breakers work with the different item running on them, great. Just remember that they wouldn't reset with the pool motor.
Problem: There were not (2) wires hooked up to the breakers. Yet the motor needed 220 volts to run. The second wire was already disconnected, had a wire nut on it. It was just sitting there, not attached. Yet the motor ran, evidently for years, with this second wire detached. There was a second power wire attached to the motor from somewhere. We were now beyond the customers level of knowledge.
How it played out:
        a.) I arrived and checked the main panel, finding it exactly as was stated.
        b.) I shut off the switch on the pool motor and checked to see if the "singular" breaker to the pool motor would reset without the motor attached. It reset. Ok. The motor, or the switch, or the wires between the switch and the motor were the problem.
        c.) So I disconnected the motor (with the switch off) and turned the switch back on. Still nothing tripped. But did I have 220 volts to the wires that were connected to the motor. I checked. I did.
        d.) This meant that there was an issue with the motor that tripped one breaker, but not the other. Time to check the wiring as it came out of the ground in the pool equipment area.
        e.) There were (3) colored (2) purple (Like the breaker box) (1) red, plus a white and a green, coming out of the ground. The purple had a wire nut on it. Hmmm chances are that it was shorted and the repair man disconnected the wire and used the red to feed the other leg. Checking the continuity between the disconnected purple wire on both ends (Using another long wire with good continuity, showed that there was a short in this wire underground.
        f.) The motor itself is bad. Also, if another wire goes in the underground conduit, chances are that all new electrical may need to be run between the box and the equipment. (Actually one more try might be possible, but it might short out immediately.)
        g.) The initial problem is related to the installers using a smaller gauge wire than they should have. First off, for a run just under 100' 12 gauge wire should have been used. 14 gauge(Smaller wire) was used. Next problem. The run is over 100' the next larger sized wire should have been used, i.e. 10 gauge. The wire is (2) gauges too small. And we wonder why we have the problems we have.
        h.) The customer was informed of the issues, that one wire was already bad, that the wiring is too small, and that more problems are imminent, and the pool motor is bad. We replaced the motor last week. Everything runs, ... for now. 
          This is how the diagnosing of electrical problems goes. Trial and error, figuring out the possibilities, checking things off as you go, ... Hopefully this will help you with your issues. Please feel free to e-mail me any questions you may have on this topic. I will do my best to help. aawesomeinc@hotmail.com