In uk.d-i-y, Bob Eager wrote:

For insulation/continuity, what do people think about this, at 89 quid
from TLC?

For insulation, it's useful, I s'pose; but the more significant problems
on domestic circuits are likely to need low-ohms metering rather than
hi-ohms (you want to tell the difference between a solid and a partial
screw connection; to tell the difference between the two legs of a ring;
and so on). The kit you mention doesn't seem to do that - though the
much pricier 255-quid-plus-VAT thing below does. All-in-one meters with
low-ohms ranges are a bit thin on the ground, but Fluke do a mid-price
one (same sort of price as the insulation tester you mention) which does
a reasonable 20-ohms-full-scale, 0.01 nominal resolution, as do Wavetek
(T120B - or at least they did ;-) For Regs-conformant-final-testing a
200mA test current is needed; I don't think these multis do that, but
they're cheaper than the Robins/Seaward and so on things.

(Pauses to flick through RS catalogue) Hmm, not many cheaper "low ohms"
meters to be found here, in fact a dearth. For those with a bit of
electrickal skill, making up a Wheatstone bridge with a decade or
binary box of low-value reference resistors might be a more affordable
way of doing Low Ohmage, as might the more direct route of creating a
200mA constant-current source (hey, may as well use the current the
Regs tell us to!) capable of developing, say, 10V, then use the
"normal" low-voltage sensitivity of even a cheapie multimeter (2V
full scale, nominal 1mV sensitivity) to measure the voltage dropped:
each 200mV means 1 ohm, thus allowing quite reasonable sensitivity.
Absolute accuracy will be poor, granted; but you'd certainly be able
to do the ring-resistance tests with such a rig, and you can calibrate
with a decent 0.5ohm wirewound or similar...

Stefek, rambling on.