So the real big question is why don't we loop test here in the USA. Some have said ,it's because it not in the NEC and the instrument manufactures are reluctant to launch the units here for that reason.There is no code that says we have use a multi meters , clamp meters to test voltage or amperage either. It would seem like a really good idea. Many time I have customers that have fires , floods . It would be an excellent way in my opinion to trouble GFCI problems .loop test to located the affected areas.To narrow it down we then then could use a megger to find the melted wires. The loop test would be a terrific trouble shooting tool for finding high impedance ,loose connection and to prevent fires , also takes us of the hook in a court of law that our work was tested at the time of installation .
Loop testing and insulation testing are excellent tools, in my opinion. Back in the 1950's/60's Megger used to publish a lot of little booklets to accompany its range of test meters explaining the benefits of such tests, and setting out how keeping records over a period of time could enable potential issues (deteriorating insulation in motor windings, for example) to be detected before they became full-fledged problems requiring immediate attention.
However the rule book which is not law is universal our BS7671 lays out what we should do with low voltage (below 1kV) and is regarded as being law by many.
The National Electrical Code here is not law in itself either, however just about all jurisdictions adopt it into their state or local building codes, thus requiring it to be followed (although obviously there is a lot of unpermitted work which can be as good or as bad as that found in Britain). The NEC is generally revised every 3 years or so, but does not automatically become the new standard when published, since each state has to adopt it formally. Some states seem to be quick at adopting the new editions, while others sometimes lag two or three editions behind. States can adopt the NEC as is, or can make amendments imposing stricter requirements or relaxing certain requirements. Counties and cities can also introduce local amendments, e.g. while NM-type cable (Romex - equivalent to British T&E) is generally permitted throughout normal residential construction the City of Chicago doesn't allow it, requiring everything to be run in conduit or equivalent.
Will the loop impedance tester trip on test a combination arc fault breaker? Like it will an RCD?
Yes, any combination AFCI/GFCI is liable to be tripped due to the earth current.
I read on wiki that the arc fault needs to see 75amps arc magnitude to trip This is with the newer combo type. They must be talking about the interrupt current? The electronic sense coil must be in the mili amp range I would think? So that would test the trip sencer. How would you test the 75amp
Threshold?
Would using a fluke 1654b perform this test?
Will the tester produce a series arc or parallel arc to test the breaker is function
I have heard arc fault have some limits?
I've not had dealings with AFCI's personally, but I'm not struck on the whole idea. I remember debating with some of my American friends when they starting appearing widely, and many of them had concerns about their usefulness as well. I recall there had also been some tests done which showed they were pretty ineffective with certain types of arcing anyway (I can't remember if it was parallel arcing such as from a damaged cable with lines in contact or series arcing under load such as could happen at a loose connection). Leading back to the original point, I'd much rather employ good wiring practices backed up with thorough testing to ensure that arc faults are unlikely to happen anyway.
Wire nuts were used on early UK installations, they were called 'Screwits' and were made of ceramic material. They were prone to falling off, no matter how well fitted. Maybe that's why they have a bad reputation here.
My feelings are that wire nuts as used here are perfectly fine so long as the correct size is selected for the conductors to be joined and that they are installed correctly. The metal coil spring inside bites into the conductors slightly to give a good, tight connection. They've been in widespread use for over half a century now, so if there were any real concerns they would have been abandoned long ago. The problems come when somebody doesn't line up the conductors properly or tries to get by with one which is too large or too small for the conductors. Or simply doesn't tighten it down properly, of course!
What I would like to see scrapped are the horrible push-in terminations on some of the cheaper receptacles and switches. I'm sure that the few seconds they save on installation must be far outweighed by the time spent replacing them later when the connections start working loose.