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EICR and IR Testing

Former Community Member over 4 years ago

Oh the bane of IR testing on EICRs

Now its just impracticle to disconnect all loads to carry out IR testing, I think everyone can agree on that. And that Phase and Neutral are connected then tested to earth.

This is what I do, and then test @250V as to avoid damaging any equipment in the installation. And unless the IR value was <.5 Meg, would not bother me. What BS7671 states, but BS7671 is maybe somewhat unclear in that if that voltage (250V) was used then .5meg value should used, but that value should only be used on SELV, and PELV. Now experience also tells me that even if you had a return 0.0, and then did Kohms by using the ohms setting, even values of 100Kohms are fine. (Actually can be much lower than this) and we are pretty clear that its not the cable reurning these values.

So question is when doing an EICR @ 250V, at what point would you recommend an FI? For me the value would have to be <.5Meg

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0 Former Community Member over 4 years ago

It rather depends what failure mode you are expecting, actually neither 230V nor 500V will 'jump' very far without assistance - much like a welding rod, contact has to be made either mechanically or by a signifiant over-voltage, and then an arc can be drawn out to a volume of hot gas limited only by the available power. Usually when this finally goes out the conductors have burnt back well beyond any re-striking distance. Equally for finding nails in the wire, trapped wires in backboxes or similar, a battery and bell set would probably do.

I agree a 500V test will find a few things a 250V test will not, and a 1000V test will find a few more.

In some ways the standard 500V test looks a bit feeble, given the overvoltage categories defined in IEC 61010-1

1500V for Cat I, (operation with protective low voltage), battery-operated devices, car electrics)

2500V for Cat II (household appliances, portable electrical appliances) and

4000V for Cat III (loads with direct fixed connection, distribution, fixed installation appliances in the distribution system)

Thanks for your answer, but was looking for testing LV in regards to BS7671, and at no point does that publication suggest using these values.
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0 Former Community Member over 4 years ago

It rather depends what failure mode you are expecting, actually neither 230V nor 500V will 'jump' very far without assistance - much like a welding rod, contact has to be made either mechanically or by a signifiant over-voltage, and then an arc can be drawn out to a volume of hot gas limited only by the available power. Usually when this finally goes out the conductors have burnt back well beyond any re-striking distance. Equally for finding nails in the wire, trapped wires in backboxes or similar, a battery and bell set would probably do.

I agree a 500V test will find a few things a 250V test will not, and a 1000V test will find a few more.

In some ways the standard 500V test looks a bit feeble, given the overvoltage categories defined in IEC 61010-1

1500V for Cat I, (operation with protective low voltage), battery-operated devices, car electrics)

2500V for Cat II (household appliances, portable electrical appliances) and

4000V for Cat III (loads with direct fixed connection, distribution, fixed installation appliances in the distribution system)

Thanks for your answer, but was looking for testing LV in regards to BS7671, and at no point does that publication suggest using these values.
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EICR and IR Testing

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