ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades FAULT LOOP IMPEDANCE METERS AND RCD TRIPPING

Loop impedance tests are specified by BS7671 (IEE Wiring Regulations).

That means that from a legal point of view, the test would be mandatory in any situation in which compliance with BS7671 is required by law. These days that would mean just about any commercial premises, as I believe that the Health & Safety at Work Acts would apply.

For domestic, at present, BS7671 is recommended, but not obligatory, although plans are in the pipeline to change this.

Scotland has slightly different laws to England, and I think David will confirm that BS7671-compliance is required for all new residential installations under the Scottish building regs.

400V,
I've just been reading AS/NZS 3000:2000
and 6.3.4.2.1, states that the Earth Loop MAY be measured to verify that the circuit protection will operate.....
Note 2 to this clause says this
Also, did you know 400, that Appendix B to this Standard gives actual values of earth loop impedance opposed to disconnection times and lots of diagrams and other pretty pictures!.

Paul,
Just as an aside, it's great to see that the members that we have, are right up with the play and can answer questions "on the hop" like that, eh?.

Hear hear Trumpy!

We have a diverse enough bunch here that no matter what the question, there's bound to be someone who can answer.

Yep, You guys are good ...