wrote:

I've just had an electrician around who says my lazer printer may be
surging in its power usage which trips the overload protector switches
(what used to be fuses).

The only way this makes any sense is if your circuit is already loaded
upto and probably beyond the maximum. This seems unlikely but is
possible - you would need something like 8kW or more of loading on a
ring circuit to get into this state. The laser printer may have an
"instant on" fuser that draws 10A or so for a short burst to heat the
fuser when you start printing.

If this is the case, I will find out, but I have a problem with
printing now - what do I do to protect the mains ring from tripping if
the printer does indeed overload it?

Supply if from a different circuit.

The electrician says the fuses
on the box are pretty standard (40 watt limit I think he said).

I expect you misheard that bit...

The electrician says he has encountered this before. So the printer
overloading is probably the problem (I suppose they use a lot of
watts).

They can use a significant amount compare to most bits of IT kit, but I
have never heard of it being a problem in a domestic environment.

--
Cheers,

John.

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