whisky-dave wrote:

On Monday, 20 November 2017 13:55:26 UTC, Roger Hayter wrote:
whisky-dave wrote:

On Friday, 17 November 2017 18:07:55 UTC, Andy Burns wrote:
whisky-dave wrote:

What makes you think it could only supply 140A ?. Isn't that the
case with all 32A MCB anywhere in the country

The MCB doesn't really limit how much current you can draw, it just cuts
off if you happen to take too much for too long, it's the length and
cross-section of your cables that limit what you really can draw

But I don't see how that is relivant anymore than it is in your home.
Do you consider the CSA of you're home cabling ?

The person who installs it *must* do so.

That's what I assumed from the last £30k upgrade to the electrics of the
lab. But I've no idea what sort of current carrying capacity the cable is
to our 13amp 3 pin sockets. It could be that they've used 3 amp flex, I
don't know or care. If they have used 32 amp MCBs I assume there's a
reason for 32 amp and not any other value.

And it's far better to check this out during the day when we are here than
leaving it to happen over night, it has been suggested because it gets so
cold that we should leave these heaters on overnight despite the manaual
that comes with them says they must not be left on unattended. But that is
the sort of thing I;d expect from someone in charge of this sort of things
that has their managment job because they have a degree in history or
geography.

If they cannot be left unattended (possibly after screwing to the wall)
then someone has bought the wrong item. Leaving unattended would seem to
be a rather common use case for an oil-filled electric heater.







Fortunately, if they just do
what everyone else does they may well be not far wrong.



140A at 202V is 22kW heating up your cabling, your lab should be
toasty until the fire service arrive.

What makes you think that

stick a 6" nail through the submain coming into your lab and find
out.

Why the submain ?


--

Roger Hayter


--

Roger Hayter