In message ,
"Andy Wade" wrote:

"Martin Angove" wrote in message
...

[cross-connecting ccts, RCDs]

I already mentioned that one in a previous reply.

Yes, sorry, I dived into a thread in which, for some reason, most of the
articles weren't visible.

I had the same problem which is why I went off to Google - they seemed
to have the lot. Clara and Demon don't share a newsfeed, do they?

Mind you IME of fans with switched live terminals, which is confined to one
model (Vent Axia VA100H), the current drawn via the SL is minuscule (a few
hundred uA). SL just feeds some electronics which drives the gate of a triac
in the main fan motor cct, so the motor current is always taken from the
permanant live terminal. Other designs may be quite different


That is the way I'd design it, and isn't really a problem. The problem
is that, whatever the actual current drawn, power from (as suggested)
two otherwise completely separate circuits is present on the same
circuit board, probably in adjacent tracks from the connecting block.
There is no guarantee that these tracks have 500V worth of insuation
between them. Likewise there is no guarantee that any switching device
(a triac is certainly a possibility) will not connect the "switch" and
"load" sides of itself in a failure mode, or for that matter under
normal conditions.

If such a connection absolutely must be made than the most obvious way
I can think of to do it would be some kind of relay with two operating
coils, one for "switch" and the other held on via a timer from "load".
I doubt any fan manufacturer would do this when they can get away with
a triac and an RC timer :-)

wants locking up.
No, he wants educating.

Of course - which now seems to have happened.


Well, we haven't actually heard from Mark Evans. ISTM that PoP knew what
he was talking about, didn't quite write it down clearly enough and was
then selectively quoted by Mark...

thinking straight as have had 2 hours sleep in the last 36 due to
arrival of offspring #2.

Congratulations.


Thanks! All home the same day and settling into routines again... not
much more sleep though :-/

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Don't fight technology, live with it: http://www.livtech.co.uk/
.... If at first you don't succeed, destroy all evidence that you tried.