On Sun, 13 Sep 2015 21:23:01 +0100, hqhy wrote:



"Tough Guy no. 1265" wrote in message
news
On Sun, 13 Sep 2015 20:38:32 +0100, hqhy wrote:



"Tough Guy no. 1265" wrote in message
news On Sun, 13 Sep 2015 20:00:56 +0100, hqhy wrote:



"Tough Guy no. 1265" wrote in message
news On Sun, 13 Sep 2015 19:04:50 +0100, John Rumm
wrote:

On 13/09/2015 16:39, Tough Guy no. 1265 wrote:
On Sun, 13 Sep 2015 16:33:51 +0100, ARW

wrote:

"Tough Guy no. 1265" wrote in message
news

Actually, my willingness to bend rules to get the job done was
welcomed at
the two main jobs I've worked in.

Bending the rules is not the same thing as leaving an electrical
installaion
in a dangerous condition.

The rules we are talking about are those concerned with being overly
cautious, so in this case, they are precisely the same.

irony_mode

Yeah this is one of those two sides of the same coin things....

We have a situation where the circuit that someone has isolated and
tested dead, can now randomly become live again, st the whim of a
neighbours cat that decides to walk up a path and trigger a PIR.

To you apparently even giving this scenario even a moments
consideration
is being "overly cautious".

To us it indicates that you are a complete imbecile, and letting you
near any electrical installation would likely be criminal negligence.

/irony_mode

Actually it can't. For the circuit to backfeed, both sensors need to
switch on the light at once.

Wrong.

If you've switched off the input power to one of the sensors, it
cannot
operate.

Wrong.

I'm right, if you think I'm not, prove it. A sensor needs power to
activate the relay. It cannot have this until its source circuit is
made
live, and you switched that off. All the other sensor can do is connect
live to the output of the relay contact of the first sensor. This will
not power up the first sensor so its relay remains open.

That assumes the PIRs produce power when not activated but powered.

False assumption with all of them.

I assumed no such thing. The relay of the sensor is open when sat in the
box before you connect it up. It remains so unless it has power given to
it on its own circuit, and detects movement. If you switch off one of
your two circuits, this means one of the PIRs cannot connect live to the
lamp, so there is no way for backfeeding to occur.

There is more than just the PIRs involved,
there is also the manual override switch(es)

Why on earth would you switch on one of those to deliberately electrocute yourself?

And the PIRs can be connected in parallel rather than in series too.

Of course they're connected in parallel. That's what I have assumed in the above.

--
Mistress: Something between a mister and a mattress.