C2 EICR on lighting

Did they test the RCD and did it pass? Did they measure the earth leakage current?

If the RCD was fitted since 2018 it comes under 18th edition:

"As such, BS7671:2018 now incorporates regulation 531:3:2 – ‘Unwanted tripping’. It states “in order to avoid unwanted tripping by protective conductor currents and/or earth leakage currents, the accumulation of such currents downstream of the RCD shall not be more than 30% of the rated residual operating current’."

You could put the sockets on a separate RCBO to keep them happy? Most of the earth leakage is due to electronics. Is there space in the box holding the RCD?

Theo

The report should include the regulation for the failure.

Reg 314 Division of Installation may apply.

The inspector needs to justify the C2 with the appropriate regs. Remember that C2 is potentially dangerous.

There is a theory amongst some that if a fault on one circuit also causes other circuits to trip (especially the upstairs lighting circuit) then people will always fall down the stairs and die.

Now how many homes lost power in the storm last week and how many human lemmings did we have?

The full quote of that section in 18th edition Amendment 2 (2022) is:

Residual current protective devices shall be selected and erected such as to limit the risk of unwanted tripping. The following shall be considered:

(i) subdivision of circuits with individual associated RCDs. RCDs shall be selected and the circuits subdivided in such a way that any earth leakage current likely to occur during normal operation of the connected load will not cause unwated tripping of the device. See also Section 314.

(ii) the use of RCBOs for individual final circuits in residential premises. See also Section 314

(iii) in order to avoid unwanted tripping by protective conductor currents and/or leakage currents, the accumulation of such currents downstream of the RCD shall be not more than 30% of the rated residual operating current.

NOTE 1: This will also allow a better selection of the type of RCDs according to the nature of the circuit or the load

NOTE 2: RCDs may operate at any value of residual current in excess of 50% of the rated residual current

(iv) use of short time-delayed RCDs, provided the applicable requirements of Chapter 41 are met

NOTE 3: In the case of transient effects, tripping of the RCD may occur by charging of bypass capacitors or by other electromagnetic disturbances.

(v) coordination of general type RCDs, selective type RCDs and time-delayed RCDs (CBRs according to BS EN 60947-2) as covered in Section 536

NOTE 4: CBR is a circuit-breaker incorporating residual current protection

(vi) coordination of RCDs with surge protective devices (SPD) according to Regulation 534.4.7

The only difference with the original 18th edition (2018) is the insertion of part (ii).

Theo

Many thanks for reply.

Yes, I understand the argument but can't see chapter and verse on this subject. I've done lots of Google searches and can't see anything on this subject.

He said system would have a C2 from "nuisance tripping" without providing the appropriate regs. He then said the house would require a rewire to bring it up to standard because the lighting was on a single circuit.

The wiring is quite old but someone has fitted a whole circuit RCD before a consumer unit that is fitted with rather dated CBs.

I wonder if some form of emergency lighting over the stairs would be sufficient mitigation. Many, many years ago I fitted a emergency luminaire over cellar steps because the consumer unit was in the cellar and had a awful set of steep steps without a handrail.

While I agree for new installs, this would be 17th Edition, or even 16th.

I don't have a copy of those, but if the section doesn't appear then I suppose it would be ok if 17th or 16th rules applied (ie no work had been done on the system since those dates). In which case they may be retroactively applying 18th edition rules to an earlier installation.

Under those circumstances it seems more like a C3 than a C2.

Theo

We had nuisance tripping - too many electronic devices, with filters leaking to earth.

We've had none, since I took out the RCD and replaced all the MCBs with RCBOs, so each only had to deal with the leakage on that circuit. Fortunately the manufacturer of the consumer unit did drop-in replacement RCBOs.

I went from a split load CU with a RCD and 6 MCBs to a new CU with 18 RCBOs.... never had a nuisance trip since the change.

Used to have lots of nuisance trips on the old CU.

Yes, if a total failure of lighting would be dangerous, then emergency lighting is the correct resolution, as even without the RCD the incoming supply is a single point of failure. And if a total failure of lighting is not dangerous, then there's no justification for demanding the RCD be replaced on safety grounds.

Mike

I would give it a C3 with or without emergency lights. It's a nuisance trip not a potential danger and I would have quoted reg 314 or reg

Obviously the house electrics are are not up to date. Any other info such as elderly person with needs living there etc or is it a case of f*ck off it's my house?

We lost a freezer-load of food - twice, before we put in the RCBOs. As we have so much electronics, I added an SPD as well.

A friend's EICR certificate is going to lapse soon and I contacted an electrician on behalf of a landlord friend. I described the system and he said it would fail on a C2 from 'nuisance tripping'. He said the 'danger' from being being dark with no lighting after a nuisance trip.

He then quoted for a new consumer unit, and after I said I believed the lighting circuit was currently a single (I will need to recheck) and not split, he said it would need a full rewire.

Many thanks for your insight.

TBH I fitted it out of common sense rather than complying with any regulation, as it would have been me having to negotiate the steps!

There is an appeals procedure if you believe the electrician is wrong.

I have just been through one.

If you win then the report has to be rewritten with the correct codes.

Thanks, that's useful.

I presume it's all complicated for the tester as each version of the regs is deemed safe, and difficult to know which edition applies.