On Sat, 08 Sep 2012 04:49:56 +0100, John Rumm
wrote:

On 08/09/2012 01:06, Graham. wrote:
On Sat, 08 Sep 2012 00:48:42 +0100, John Rumm
wrote:

On 08/09/2012 00:18, Graham. wrote:
On Fri, 07 Sep 2012 23:51:05 +0100, wrote:

On 7 Sep,
Graham. wrote:

The last 3 or 4 times I have visited them I have heard a thud, and the
lights blink at the same moment. This happens maybe twice per hour,
but not regularly enough to be able to predict the next event.

The freezer starting up?

I see what you mean, and maybe Nick had this in mind too. It might
account for the timing intervals, the inrush surge of the motor
starting acting as the cartelist to set whatever it is off upstream.

The inrush for an induction motor can be enough to dim the lights for
the whole house just on its own...

I'd appreciate your view on what might be causing the thud John.

Without hearing it, I am not sure I have one to be honest...

A motor kicking in would be one option. Slightly percussive ignition of
a boiler could also cause a thud (although that would not typically be
associated with any electrical drop out).

Big transformers at switch on can have similar effects.

Automated systems like heating and cooling devices would obviously be
prime candidates.

I've pretty much convinced myself it's something electrical blowing
itself apart in a self resettable way. Maybe water gets into a joint
and is instantly and explosively superheated, Do you think that could
happen on a circuit protected by a 30 amp fuse, again and again
without it blowing? I think the answer is yes if the loop impendence
is high and the events are of short enough duration.

I'm just afraid that it might be a cable protected by a fuse 10 times
that value in a substation!

Can't you sleep?

--
Graham.
%Profound_observation%