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Thread: COC & Alternative power

  1. #1
    Full Member Tonye's Avatar
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    COC & Alternative power

    Hi all,

    Busy with a COC at a residential property.

    There is a changeover switch connected to a Briggs & Stratton 9000ea

    Tested earth leakage with mains on. Tests fine & trips at 20ma.

    Changed over to Generator.

    Tested earth leakage with generator running.
    Get 3 lights on tester, but when button is depressed, instrument shows earth fault.
    Cranked milliamps to max but failed to trip

    Told client there is a problem & wanted to do some voltage tests. However he was upset & stated professional people had installed the system.

    I left without any further testing pending the client calling out the guys who installed the system.

    Did some googling on the 9000ea & could not find specs pertaining to winding connections ie VOV.

    Does anyone know if this model is VOV

  2. #2
    Diamond Member AndyD's Avatar
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    Quote Originally Posted by Tonye View Post
    ......Does anyone know if this model is VOV
    This was my first thought when I read your symptoms but it could also be that it's standard wired and the neutral and earth aren't bonded. Even if it is V-O-V you can sometimes convert them by disconnecting the centre-tap of the windings and creating a N-E bond.

    Can't help you I'm afraid, I've no experience with this specific make and model number. You can often figure out how it's configured by manually tracing the wiring. If it's V-O-V the earth/chassis will always be exactly 110v wrt both neutral and live at all times regardless of what load is connected. If it's standard wired with no neutral-earth bond then the voltage of both the live and neutral will float wrt earth. If you're unsure I'd suggest track down the suppliers or agents for the circuit schematics.
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  3. #3
    Full Member Tonye's Avatar
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    Thanks Andy,
    as mentioned I wanted to do some voltage tests but the client was upset & decided to leave it in the hands of the guys who installed it.
    I will go back once sorted & test to ensure all is well

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    Diamond Member AndyD's Avatar
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    I wish you luck. I've attended over a dozen premises with non compliant generator installations in the last year and the client is never happy when they find out. I'm guessing it was during the loadshedding epedemic when many contractors with insufficient experience jumped on the bandwagon of selling/installing generators.
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  5. #5
    Full Member Tonye's Avatar
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    Hi Andy, the client has not arranged with the orginal installers of the generator to sort out the wiring to be compliant.
    I decided that I do not wish to be involved in determining if it is VOV wound & further to ascertain if the centre tap can be disconnected from earth & bridge the neutral to earth etc..

    I have issued a COC, specifically excluding the Alternate power & stated that a supplementary COC will be issued by the installers for the Alternate generator supply.
    The client is upset with me, as he cannot believe that the installation is non compliant.
    When I asked wether they had issued a COC, he said that they were proffesionals?

    Shortly after I did the earth leakage test while using generator power which did not trip & showed an earth fault,
    the client emailed me, stating that since I left his oven was not working properly as well as his DSTV decoder.
    He did all the switching & started the generator. All I did was the earth leakage test.

    I replied & stated that after conducting all tests ie PSCC, Earth loop impedance, Earth leakage etc.. with Eskom power being supplied, there
    were no problems with his appliances.

    The only thing that is common with regards to the problems is that the power was supplied by the generator.
    I aslo stated that Decoders do not like to be switched on & off repeatedly & can fail prematurely, especially PVR's which normally experience hard drive failure.
    I am also assuming that his oven has some type of electronic control regarding heating & timer, which could be affected by Generator power ie, voltage, current & frequency.

    On a funny note. Did a COC the other day. When I opened the DB, this is what I found.

    Click image for larger version. 

Name:	snake.jpg 
Views:	53 
Size:	59.5 KB 
ID:	6436

    Took half an hour to remove this guy.

  6. #6
    Platinum Member SilverNodashi's Avatar
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    Quote Originally Posted by Tonye View Post
    Hi Andy, the client has not arranged with the orginal installers of the generator to sort out the wiring to be compliant.
    I decided that I do not wish to be involved in determining if it is VOV wound & further to ascertain if the centre tap can be disconnected from earth & bridge the neutral to earth etc..

    I have issued a COC, specifically excluding the Alternate power & stated that a supplementary COC will be issued by the installers for the Alternate generator supply.
    The client is upset with me, as he cannot believe that the installation is non compliant.
    When I asked wether they had issued a COC, he said that they were proffesionals?

    Shortly after I did the earth leakage test while using generator power which did not trip & showed an earth fault,
    the client emailed me, stating that since I left his oven was not working properly as well as his DSTV decoder.
    He did all the switching & started the generator. All I did was the earth leakage test.

    I replied & stated that after conducting all tests ie PSCC, Earth loop impedance, Earth leakage etc.. with Eskom power being supplied, there
    were no problems with his appliances.

    The only thing that is common with regards to the problems is that the power was supplied by the generator.
    I aslo stated that Decoders do not like to be switched on & off repeatedly & can fail prematurely, especially PVR's which normally experience hard drive failure.
    I am also assuming that his oven has some type of electronic control regarding heating & timer, which could be affected by Generator power ie, voltage, current & frequency.

    On a funny note. Did a COC the other day. When I opened the DB, this is what I found.

    Click image for larger version. 

Name:	snake.jpg 
Views:	53 
Size:	59.5 KB 
ID:	6436

    Took half an hour to remove this guy.
    Rinkhals?

  7. #7
    Diamond Member AndyD's Avatar
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    Aww, shame, was he still alive?

    Getting blamed for appliance failures is quite a common thing, unfortunately sometimes it's an opportunist who doesn't want to pay, other times they're genuinely convinced that anything that stops working within several days of an electrician visiting must be the electricians fault. As a matter of course I basically run through what I'm about to do with the customer and request that they unplug any equipment that might be sensitive to power fail. This at least puts the ball somewhat in their court regarding anything that may go tits-up. Also with IR tests I usually common the L+N together when using a megger tester but even taking that precution won't prevent damage occuring to network items that have earth referenced comms. If all else fails there's always insurance to fall back on but, touch wood, I haven't had a claim in the last couple of decades.
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