"Tough Guy no. 1265" wrote in message
news
On Mon, 14 Sep 2015 21:13:02 +0100, ARW
wrote:

"Tough Guy no. 1265" wrote in message
news
On Mon, 14 Sep 2015 20:19:12 +0100, ARW
wrote:

"Tough Guy no. 1265" wrote in message
news
Why would you assume they were on the same circuit?

On a installation that meets the IET regs than I would expect them to
be
on
the same circuit.

However I assume nothing as I have seen some right bodge jobs (and not
just
from DIYers).

Assuming someone else has done something a particular way is stupid,
which
is why you don't. So you've just answered your own question. It's not
dangerous to have two circuits, as people like you check.

You cannot always tell if two circuits are/may be connected together via
bad
workmanship unless you have stripped the house apart to check every last
electrical connection.

The best solution is just to wire the job up correctly in the first
place.

As I've already said three times, you walk in front of both PIRs and make
sure neither make the wiring live.

No easy way to do that last with all the wiring.

Makes a lot more sense to turn the entire house off
if someone like you has been doing anything to it
and even that isn't complete protection so you
basically have to treat it as still live even with the
entire house turned off.