On Wed, 4 Feb 2009 00:13:17 -0000, JDT2Q wrote:

if the bell transformer consumed 100mA ( not yet measured it so I may be
way out )

Do the maths on P=VA, 24W of losses in a transformer how hot does this
thing run!

You can probably disconnect the transformer and patch batteries in
instead. The bell only takes power when the push is pressed, batteries
last for donkeys years.

my supplier charges 9p per kilowatt hour ( excl VAT )

That's a good ball park price these days.

I'm thinking of swapping power supplies for these 'traditional' items to
SMPU's - easy for the door bell, not as easy for the alarm system.

Might be worth it for the alarm but feel the transformer, I really don't
think there will be much loss in it to be honest.

We have several modern devices powered up 24/7/365, cable modem, router,
network switch and the usual videos, TVs etc.

All those things taking power, the modem/router/switch are probably 30W
all together add in the TV's Videos and other set top boxes and you might
be looking at 2 units/day or £60/year.

I know the real killers are tumble driers, cookers, washing machines etc
as regards electricity consumption.

Tumble dryer as they take quite a bit for a long time. Other things may be
high loads but don't take high power for long. Fridges and freezers
consume quite a bit are they A or A+ rated appliances?

--
Cheers
Dave.