On 15/11/2017 17:17, whisky-dave wrote:
On Wednesday, 15 November 2017 15:25:45 UTC, John Rumm wrote:
On 15/11/2017 11:30, whisky-dave wrote:
On Tuesday, 14 November 2017 16:53:40 UTC, John Rumm wrote:
On 14/11/2017 11:03, Roger Hayter wrote:
John Rumm wrote:

On 13/11/2017 20:38, Roger Hayter wrote:

It seems he already has as much electrical heating as that
autotransformer will ever supply, and is probably exceeding its ratings.
Perhaps someone who knows where it is could have a quick look and see if
any smoke comes out when the voltage drops to 202V?

ISTR that bigclive did a tear-down on one of those voltage reduction
units. At some load point it actually had relays to bridge itself out of
the supply as a self protection mechanism. So you may find enough load
actually takes it out of circuit.

That sounds a sensible arrangement, But doesn't the marked voltage
drop make it a bit unlikely?

It would depend on where it bridged itself (if it does). It might
already have done that, in which case the measured voltage is even more
worrying!

doesn't worry me in the least because I expected it.
That's the advantage of understanding both theory and the real world.

Hmmm Dunning Kruger at work perhaps...

If the wiring is underspecified,

so why did we pay £30K for higher capacity electrics ?


that would suggest that close to full
load it is running at over them maximum continuous conductor
temperature rating of the cable. So expect shortened cable life and
elevated fire risk.

Over the life of teh cable we ran it for about 2 and a bit hours after teh 32A MCB tripped we removed 3 of teh 5 heaters and put 2 on another 32 amp MCB and the final heater on another phase our 'CU" has a 'cut-out rated at 100 AMPS.
I di not think the life of the cable will be significantly shortened because we have 5x 2Kw heaters that spend most of there time at 700W .

I am assuming you did not have a rewire done just prior to running this
experiment?

If this experiment *has* demonstrated that the installation was sub
standard, then it has likely been that way for some time.

If the voltage sags too far, then you get lower PSCC so can expect
slower operation of protective devices under fault conditions, so
increase electrocution risk, and catastrophic cable failure risk.

But not in under 3 hours.

It was not the 3 hours that would bother me. Especially if anyone is
considering running with this daft idea for any extended period.


--
Cheers,

John.

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