In message ,
"Smudger" smudger@here wrote:


"Martin Angove" wrote in message
...
In message ,
"Smudger" smudger@here wrote:



You should be aware that you are required to put switchgear (i.e.your
Consumer Unit) on a fire proof back-board. Chipboard is fine, provided
you
have put a couple or thee coats of oil-based varnish on it first. A
plastered wall is inherently non-flammable.


Interesting that I've never seen the electricity board do this :-)

My understanding was that with modern enclosures (metal or
flame-retardant plastic) the fireproof backing was no longer necessary:
it was really there for all the older-type fuse boards which were open
at the back.

Woteva :-)



Regulations 421, 422, 527-01 apply. I guess you can interpret them as you
see fit. I always take it to mean that you should not put your CU onto bare
wood. I'm sure I have read or been taught about this issue in the past, but
it could be as long as 20 years ago, and I can't find any direct reference
to it at the mo.


421 deals with "heat developed by electrical equipment". Under normal
circumstances I would not expect a consumer unit to generate a
significant amount of heat. Certainly if it did, I would be very
surprised if a lump of chipboard an inch away from the MCBs caught fire
before the plastic case of the CU had melted away. It takes a *lot* of
heat to cause "bare wood" to burn. To prove this to a H&S inspector at
a previous place of work who was complaining about our (electronic)
soldering activities on a solid wood worktop with hardboard face we
drilled a hole in the worktop, left the sawdust inside, turned our 40W
iron up to full temperature, removed the bit and stuck it in the hole.
It smelled a bit, but didn't catch fire in the 2 hours we could be
bothered to wait.

422-01-01 yields to the same argument

422-01-01 does not apply because a CU does not have "in normal operation
a surface temperature sufficient to cause a risk of fire or harmful
effects to adjacent materials".

422-01-03 does not apply because a CU does not "[emit] an arc or high
temperature particles"

422-01-04 applies but refers to 526-03-02 which states that the
enclosure for the termination or jointing of live or PEN conductors
should be made in (for example) "(ii) an equipment enclosure complying
with the appropriate British Standard". I have always assumed that the
appropriate standard is the one stamped on the likes of junction boxes,
sockets, surface patresses and CUs. Do you make sure a socket is mounted
on a fireproof backing material?

422-01-05 does not apply because a CU does not contain "flammable liquid
in excess of 25 litres"

422-01-06 might apply, but not if the CU and the configuration of its
circuits has been appropriately selected. (It deals with "equipment
causing a focusing or concentration of heat").

422-01-07 applies, but as with -04 I assume that this is the BS to which
CUs are made.

The key phrase here is, I think "enclosure". A modern CU is an enclosure
where an old-fashioned wooden-framed CU was not.

527 is generally concerned with the spread of fire through a building;
between compartments, not necessarily within a compartment.

527-01-01 and -02 apply but see above.

527-01-03 and -04 apply to cables, not enclosures.

527-01-05 applies to conduit and trunking.

527-01-06 might apply, but if this were the case we would have to build
a fireproof enclosure around every CU.

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Two free issues: http://www.livtech.co.uk/ Living With Technology
.... You're twisted, perverted, & sick. I like that!