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Discuss Identifying single core cpc's and neutrals in the Industrial Electrician Talk area at ElectrciansForums.co.uk.

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  1. moosey86

    moosey86 Regular EF Member

    It's a lighting board and they will be disconnected for seconds.
  2. Vortigern

    Vortigern Electrician's Arms

    I am sure you were really just speculating on the idea of disconnecting earths (I hope!) I am also sure you full well know the risks and regs around such a course of action. So I will not impugn your standing in the trade. I think Luciens ideas are doable, I was thinking of a small d.c. voltage (1-2v) or possibly a linesman phone at each end. Not sure how practical that is mind you. I have a cable detector that identifies up to 16 cables at a time but that is for dead circuit sadly. I do think you may find it worthwhile to flag this as a needed part of planned maintenance so when a machine is down you can test ccts for the earth in the future. As identifying correctly ccts is as important as not disconnecting the earth. As it is lighting can you not arrange for out of hours switching off? And are the circuits not placed by numbers on the board like neutral/mcb 1/cpc in 1 terminal etc?
  3. westward10

    westward10 Electrician's Arms

    Top Poster Of Month

    Isolate the board, link cpc to line or neutral at end of circuit. Disconnect all cpcs in the board and assuming parallel paths don't exist you can trace the cpc by a continuity test.
    Davisonp likes this.
  4. moosey86

    moosey86 Regular EF Member

    Cheers Vortigern,

    I did like luciens idea, I think this is the route I will try because it is a common problem in old installations and I have wondered for a while if there was a method that was practical.

    Unfortunately the factory is 24 hours all day everyday so it's something I'm going to have to deal with in some way. I've basically got a dis board mounted right next to the existing one with a temp supply and I'm installing emergency lighting and gradually swapping over the circuits to the new board one at a time. Once they're all done I will arrange a shutdown to change the existing dis board to an isolator which will feed the new one.

    The existing circuits are numbered so the chances of getting the correct cpc are high. I could switch off and r1+r2 it, I just have to keep it to minimal disruption.
  5. moosey86

    moosey86 Regular EF Member

    That's very clever Westward I'm sure the customer would be over the moon.
  6. Vortigern

    Vortigern Electrician's Arms

    Now now! I know it can get a little "heated" on here sometimes but stick with it and keep calm. There are some valuable insights between the thorns. If you get something a bit wrong (which I have!) and get a new backside ripped dont worry about it. Just make sure you take something of value away with you. They will calm down once they get to know you a bit :)
  7. moosey86

    moosey86 Regular EF Member

    No worries, I'm not one to hold a grudge. I'm also going to get to the bottom of it somehow with one of these idea's and I'll get back to the thread with how I get on.

    Sorry if I scared anyone :relaxed:
    Vortigern likes this.
  8. HandySparks

    HandySparks Trusted Advisor

    OK. How about this.
    For each final circuit. Check earth continuity by wander lead or maybe by measuring Zs.
    If properly earthed, introduce a small known 'leakage', line to cpc, say 5mA (47k, 2W resistor?). Get your mate to make and break the leakage load at 1 second intervals, to make it easier to spot. Put an earth leakage clamp meter on each cpc at the board and look for the one with current regularly varying by 5mA.
    Davisonp and moosey86 like this.
  9. SheffSimon

    SheffSimon Regular EF Member

    Who benefits from you or your lad taking these risks, however small you might feel they are?

    Not you I imagine, but the factory will, so why take the risk. I've worked in food and beverage factories for years. The ones I've worked in would run a mile from unsafe practices, and will arrange shutdowns on size/product changeovers etc if absolutely required.
    Davisonp and stantheman like this.
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