Switch on surge.

Sounds like an urban myth. Switching of E7 and similar loads is controlled by a phase modulation of 198KHz radio 4. If you have a big radio, try tuning into R4 with the BFO switched on...

James

/Some/ E7 is teleswitched. A lot isn't. timeswitches are still widely used. Some suppliers offer industrial tarrifs of variable hours which are teleswitched. You (and the supplier) get what is paid for.

snipped-for-privacy@care2.com coughed up some electrons that declared:

I don't have my books to hand, so I'll not argue. But if that is correct, then the conditions for putting in a Type D breaker or something with a similar trip curve are considerably more onerous in terms of having a low loop impedance on the local circuit *and* on the supply (ie in the event of a dead short L-E fault, would the breaker or fuse clear before the cable damages itself through overheating?).

It would be quite possible to have a perfectly ordinary and good installation where adding a type D to a random circuit would make it both non compliant and dangerous (particularly from risk of fire, but also shock if the breaker/fuse cannot reliably clear a fault.

However, this does change if there is RCD protection (don't think that was mentioned) - but even so, personally, I would want to then ensure that a L-N fault would clear in the expected times, which is an easier target to meet, but not necessarily a forgon conclusion.

I'd be cautious about jumping straight to something with that sort of characteristic without risking a few quid on the middle option first (there's always ebay if a Type C doesn't work out).

IIRC (memory poor, open to correction) a Type C is several times less sensitive on the instantaneous trip part of the curve compared to a Type B, so there's a good chance it would buy enough margin.

I'm happy to come back tomorrow and reel off some numbers, or I think if one digs into Hager's literature, the trip curves for most of their devices are in there somewhere. Might have a rummage later...

Cheers

Tim

You put the dimmer after the switches and leave it on full. A soft start dimmer will just limit the current when you switch on and do sod all once on.

NT

snipped-for-privacy@care2.com coughed up some electrons that declared:

Aye - I was more concerned about randoming banging Type D's - or something equally thick skinned - in without a more detailed test of the installation (loop impedances mainly), which is why I was discouraging it.

There are dimmers with two way switches - so assuming you leave it full up should be ok. But I'm not even going to suggest this to them.