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Commercial EICR strategy?

Former Community Member
Former Community Member
Hi,


I've been tasked to do some EICR's on some commercial Car Showrooms. There's lots of old DB's, little or no circuit details and the previous EICR's stated that nothing could be tested due to not wanting circuits switched off. Personally I don't think it's worth even reporting if you aren't testing anything?


I wondered if anyone had a strategy for dealing with these situations. I'm not looking for anymore work so I'd rather not fail anything unless I absolutely have to. The customer wants as little interruption to the supply as possible.


A possible strategy:

Visual check

Identify circuits where possible

Take Zs readings where possible

Check db's for signs of thermal damage

Zsdb and ipf's

Check bonding

Check tightness of terminals in db's and sampled accessories

Report on what I've seen and tested with limitations on everything else.


It is going to be impossible to identify cpc's and neutrals associated with each circuit. IR testing would have to be very limited.


Below is a picture of what I am up against. There's a mix of old and new db's with many BS3871 MCB's.

f3685b9e83139223d5bf313572195363-huge-honda-mains-position.jpg


Any advice guy's?

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  • 0
    There is no 'hard and fast' limit for what leakage is OK - it may be made higher if there are motors with inverter controls or lots of PCs with switch mode power supplies - normally it is the interference filters on electronic equipment that have some capacitance L-E (and N-E) that gives rise to the largest leakage component. Next after that are metal clad heating elements in cookers and kettles and so on.

    As first stab at what is reasonable, expecting no more than a mA per amp or two of circuit rating  is a good start - so a 30mA RCD covering a 30A circuit might be leaking up to 10mA or so and not troubled. For a 100A sub-main, perhaps 30mA of leakage, and so a 100mA RCD if it was a TT supply.

    However, the type of loads connected could affect this a lot - a single PC of the metal cased kind may add 3mA of leakage on its own, as may the electronics in an induction hob. Indeed sites wite many PCs (or many induction  hobs I suppose -  but less likely) benefit from being wired as a larger number of under loaded circuits - like small area rings and radials, so that the pre-load on any RCD is not too great, and the losses if it trips are minimised.

    Mike.

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  • 0
    There is no 'hard and fast' limit for what leakage is OK - it may be made higher if there are motors with inverter controls or lots of PCs with switch mode power supplies - normally it is the interference filters on electronic equipment that have some capacitance L-E (and N-E) that gives rise to the largest leakage component. Next after that are metal clad heating elements in cookers and kettles and so on.

    As first stab at what is reasonable, expecting no more than a mA per amp or two of circuit rating  is a good start - so a 30mA RCD covering a 30A circuit might be leaking up to 10mA or so and not troubled. For a 100A sub-main, perhaps 30mA of leakage, and so a 100mA RCD if it was a TT supply.

    However, the type of loads connected could affect this a lot - a single PC of the metal cased kind may add 3mA of leakage on its own, as may the electronics in an induction hob. Indeed sites wite many PCs (or many induction  hobs I suppose -  but less likely) benefit from being wired as a larger number of under loaded circuits - like small area rings and radials, so that the pre-load on any RCD is not too great, and the losses if it trips are minimised.

    Mike.

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