In article ,
Tim S writes:
Andrew Gabriel coughed up some electrons that declared:
Well, I went for the MEM (now Eaton) AM industrial range for
home...
http://www.cucumber.demon.co.uk/cu1.jpg
http://www.cucumber.demon.co.uk/cu2.jpg
It's very nice to use compared to cheap plastic ones, and
in the case of DIY, that's where you can spend the money
you saved by DIYing it, although I think you're looking
at around £320 for what's in that picture. More bits were
added just afterwards which I had to wait for as they
were ordered from MEM. This was the 3rd MEM AM range CU
I fitted in different places.
(The extra box above is to extend the wires which weren't
long enough after removing the old CU.)
That's a work of art Andrew. Where did you get your kit from? The only
online supplier of MEM I can find is www.kempstoncontrols.co.uk and even
the ready assembled RCBO's (SP/1 module) are 66+VAT. I suspect you paid
less?
I don't believe building trades people use on-line ordering
much. I bought them from trade counters; IIRC, a combination of
ERD (who stocked most things but wouldn't order anything else
except in box quantities), and Gibbs & Dandy (who didn't stock
much of the range, but would order anything even singularly).
The RCBOs you see there are all made up by me from MCBs and
RCBO pods. The RCBO pods were under £50 each (might have been
more if I was buying just one), and the MCBs well under £10
each (I tend to ignore the price of those).
I priced up the 2x AM8D board (L+N busbar, no need for neutral tails - then
one I meant above) and 11 DP RCBOs and it's that that came to 1400 ish inc
VAT. The DP MCB+MR30 field-fittable RCD module came to about
78+VAT/circuit. That's what killed it for me.
It was pushing me back towards Hager who aren't bad but the RCBOs are way
cheaper, ditto Crabtree.
On an aside, I assume you had to go with Type C overload RCBOs? Any issues
with these over Type B?
Because I made them up from separate MCBs and RCBO pods, all
the RCBOs in that picture are actually Type B. There would have
been no issue with using Type C because by definition they're
all RCD protected. If they weren't RCD protected, you'd have
to double-check the earth fault loop impedance against more
stringent values for Type C to ensure they still meet disconnect
times.
The 6A lighting MCBs are all Type C, as is a 20A radial for things
I didn't want RCD protected.
I'm aware of the argument that even on TN-S where Type C may not provide
sufficient protection against indirect contact that the RCD nullifies this
by itself providing the required disconnection time for an L-E fault, but
nevertheless...
For the outdoor sockets circuit, which is a 20A radial Type C,
I used a C20A 10mA RCBO prebuilt. That had to be ordered and didn't
arrive until after I took the photo, but it looks exactly the
same as the ones I assembled myself. At £60 IIRC, it was the most
expensive component. I went for a Type C there because I could
imagine it being used for large motor appliances. I went for 10mA
because it's generally only used for one or two appliances so
cumulative appliance leakage isn't an issue, and earth leakage paths
through you outdoors can be subject to additional external resistances
which might serve to limit the current below 30mA. That circuit is
also TT, where as the rest are all TN-C-S.
Also bear in mind my prices are ~5 years ago.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]