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Thread: GFCI breaker Tripping with time clock

  1. #1
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    GFCI breaker Tripping with time clock

    This has me stumped so I thought I would reach out here and see if anyone has run into this.

    I went to do a service call about some pool lights not coming on and discovered a bad time clock and pool lights on a regular 20 amp breaker shared neutral with the landscaping lights around the pool area.

    Moved the landscaping lights to there own breaker, pulled a new neutral for the pool lights and installed a new time clock and a 20 amp GFCI breaker for the pool lights as well.

    The time clock uses its own circuit to run and just makes a contact for the pool lights. I am having trouble with the GFCI breaker tripping. But when I come over and reset, turn on time clock manually they all work fine.

    My only thought is that the time clock gave a hardy spark when I turned it on. It is nothing special just a standard two Pole time clock. There are 6 Pool lights.

    I thought about springing for a digital time clock, but am not sure if this will help.
    Thanks

  2. #2
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    Quote Originally Posted by ShadowSparky View Post
    This has me stumped so I thought I would reach out here and see if anyone has run into this.

    I went to do a service call about some pool lights not coming on and discovered a bad time clock and pool lights on a regular 20 amp breaker shared neutral with the landscaping lights around the pool area.

    Moved the landscaping lights to there own breaker, pulled a new neutral for the pool lights and installed a new time clock and a 20 amp GFCI breaker for the pool lights as well.

    The time clock uses its own circuit to run and just makes a contact for the pool lights. I am having trouble with the GFCI breaker tripping. But when I come over and reset, turn on time clock manually they all work fine.

    My only thought is that the time clock gave a hardy spark when I turned it on. It is nothing special just a standard two Pole time clock. There are 6 Pool lights.

    I thought about springing for a digital time clock, but am not sure if this will help.
    Thanks
    What is feeding the time clock?
    If you aim at nothing, you will hit it every time!

  3. #3
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    Make certain the time clock is either not interconnected to the GFCI protected circuit at all, or is totally on the GFCI protected circuit.

    One line on GFCI and the other line to clock not on GFCI will trip it.

    Many of those types of timers have common terminal for clock motor and one of the contact lines, but may be separable if you want them on separate circuits - make sure that has been done if you have one of those.

  4. #4
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    Quote Originally Posted by Little Bill View Post
    What is feeding the time clock?
    A 20 amp breaker located at the main panel. That would be a different breaker than the GFCI one. I didn't know if it was the spark caused by the time clock making a "sloppy" connection that might trip the GFCI or if I have other issues. This building was built in the 60's but the service was just redone from the CT cabinet to the distribution panels all square D.
    Thanks for any help.

  5. #5
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    Quote Originally Posted by kwired View Post
    Make certain the time clock is either not interconnected to the GFCI protected circuit at all, or is totally on the GFCI protected circuit.

    One line on GFCI and the other line to clock not on GFCI will trip it.

    Many of those types of timers have common terminal for clock motor and one of the contact lines, but may be separable if you want them on separate circuits - make sure that has been done if you have one of those.
    The Time clock has a dedicated circuit that is separate from the GFCI. I checked the back of the time clock and followed the wires...
    If I manually throw the time clock the lights will stay on as I go outside and check them. Another "random" event.

  6. #6
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    Quote Originally Posted by ShadowSparky View Post
    The Time clock has a dedicated circuit that is separate from the GFCI. I checked the back of the time clock and followed the wires...
    If I manually throw the time clock the lights will stay on as I go outside and check them. Another "random" event.
    I don't think that's ever going to work to have the clock on one regular circuit/breaker and the lights on a GFCI circuit. Like Kwired said, it would be better to just feed the clock with a GFCI breaker and just connect the lights to the clock. They will be GFCI protected.

    There's too much opportunity for current to return on the wrong neutral and causing the GFCI to trip. Most time clocks that I've seen use a common neutral lug so if you have both the regular circuit neutral on that lug and the GFCI circuit neutral, then it will trip.
    If you aim at nothing, you will hit it every time!

  7. #7
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    Quote Originally Posted by Little Bill View Post
    I don't think that's ever going to work to have the clock on one regular circuit/breaker and the lights on a GFCI circuit. Like Kwired said, it would be better to just feed the clock with a GFCI breaker and just connect the lights to the clock. They will be GFCI protected.

    There's too much opportunity for current to return on the wrong neutral and causing the GFCI to trip. Most time clocks that I've seen use a common neutral lug so if you have both the regular circuit neutral on that lug and the GFCI circuit neutral, then it will trip.
    But the control circuit is often capable of being separated from the power circuit in most mechanical time clocks anyway. You have to separate them if using 120 volt control but are switching a 277 or 480 volt load.

  8. #8
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    Quote Originally Posted by kwired View Post
    But the control circuit is often capable of being separated from the power circuit in most mechanical time clocks anyway. You have to separate them if using 120 volt control but are switching a 277 or 480 volt load.
    That is correct, the second set of contacts on the time clock just switch the hot. The Neutral for the GFCI breaker is not run up to the time clock. And so I was wondering if I change the time clock out to a digital one or go with the time clock switching a set of contacts that do not create the large sparking effect would this solve the problem. Because the GFCI will hold if I switch the time clock manually but I still get an awful spark out of the time clock as the contacts are closing.
    Thanks again as I hate to charge the customer for something that might not be helpful. Kinda like the mechanic that looks under the hood and just starts replacing things..... just in case... ya I find a new mechanic!

  9. #9
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    Quote Originally Posted by ShadowSparky View Post
    That is correct, the second set of contacts on the time clock just switch the hot. The Neutral for the GFCI breaker is not run up to the time clock. And so I was wondering if I change the time clock out to a digital one or go with the time clock switching a set of contacts that do not create the large sparking effect would this solve the problem. Because the GFCI will hold if I switch the time clock manually but I still get an awful spark out of the time clock as the contacts are closing.
    Thanks again as I hate to charge the customer for something that might not be helpful. Kinda like the mechanic that looks under the hood and just starts replacing things..... just in case... ya I find a new mechanic!
    Is there by chance a mechanical problem with the time clock and when closing contacts automatically it isn't as clean of a make as when you close them manually?

    Breaker may even be tripping on overload instead of ground fault function in that case.

  10. #10
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    Quote Originally Posted by kwired View Post
    Is there by chance a mechanical problem with the time clock and when closing contacts automatically it isn't as clean of a make as when you close them manually?

    Breaker may even be tripping on overload instead of ground fault function in that case.
    That was my idea, and that was what my original question was if the time clock itself was causing a sloppy connection when it did it automatically... the nob slowly moving the connection arm till it over centers on the spring and ..... but I still didn't want to replace the time clock with a higher quality one and then not fix the issue.

    I did just find out today by an off comment from someone that the pool management company is having a hard time finding the j-box for one of the pool lights and wondered if I could help find it as they needed to change the light since it has gone bad....

    So I am going to wait until they get the light fixed and see if that fixes the GFCI issue...

    will keep you informed next week...

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