Staffbull wrote:
Matt wrote:
On 2 Oct 2006 10:19:09 -0700, "Ren"
wrote:

Don't worry - there is lots of info regarding split CUs in the d-i-y
archives. After a lengthy study, I have come to the conclusion that
the cooker stays off the RCD (as you have suggested) as most cookers
'leak' anyway.
Which is fine right until the point the oven element fails and the
break in the earth conductor in the consumer unit that has gone
un-noticed for months/years/forever means the fuse doesn't blow and
the oven casing rises to mains potential.

A fatal shock is about the 6 inches of reach between the oven and the
nicely bonded "split level" gas hob sat right above it.

Apart from the last bit which was narrowly avoided by the owner
switching off the cooker at the wall switch the above is actually what
happened on an installation a few weeks ago. The earth had failed
right in the middle of a sleeved run in the consumer unit. A simple
visual examination wouldn't have picked it up.

Put the cooker on the RCD!


--

I'm now as confused as a baby raccoon !!!

Welcome to the 'safety mens falling down the stairs in the dark, because
you have a 30mA trip and the electronics draws 31mA' brigade.

My first thought was to RCD everything apart from the lights, is this
sound? the cooker and hob both have seperate radials as they are more
than 2m apart (as per regs).

Look. Houses all 'leak' a bit. Apart from stuff like cookers and kettles
that have to balance insulation integrity with high temperatures and
cheap cost, steamy rooms and a sweaty thumb print can cause a few mA
leakage, every RFI filter in every bit of electronics adds one or two
more, the wiring capacitance of all your wires adds a bit more..

I don't regard any wiring as potentially untouchable, so I like an
overall RCD including lights.

BUT experience shows that a full house 30mA trip is always tripping for
no bloody reason at all. Especially if you have as many TV's, computers,
mast head amps, routers, printers and the like as I have.

HOWEVER the regs state that outside sockets have to be on a 30mA RCD.

In practice this means split load or RCBO.

I personally like an RCD protected HOUSE, but set at a level that
doesn't do nuisance trips., Here its 100mA. In a small house or flat,
30mA is probably OK on everything.



What size MCB should serve the cooker & hob (seperateley) the CU came
with five 32's one 40 three 6's and one 16.

Depends on the cooker wiring. And the cooker rating. The MCB is there to
protect the wiring to the cooker though.