mem 2000 cu

[nabby68]

Hi all,
I have just moved into my new house and require a bit of advice regarding the cu.
The cu i have is a mem 2000 eight way with 100a mains switch. I have the following circuits installed
1. 6a mcb for downstairs lights
2.6a mcb for upstairs lights
3.6a mcb for smoke detectors
4.16a mcb for hot water cylinder
5 32a mcb for oven
6 16 a radial for sockets
7 32a ring main rcd protected mcb for sockets

now, i wish to put in a 9.5 kw electric shower using 10mm cable and a 45amp mcb. The cable will be run mostly in conduit and in thermal insulation, so i believe this is all correct?
But, i would like the shower to be rcd protected, so does this mean a change of cu, to accomodate a split load, my sockets and shower being rcd protected, and the rest of the circuits on the other side of the rcd protection. Or, is there a way to accomodate all of the above with the exsisting cu?

 

[Lectrician]

You say circuit 7 IS RCD protected?? Or is that a type?? Did they use an RCBO?? You could use one of these for the shower, but space is limited in a domestic board with an RCBO, and 10mm cable.

You could put an RCD in a seperate enclosure outside the CU, although the materials for this would be the price of an empty 10way split. An MEM 10wayt split shouldn't cost you more that £50, and you have the MCB's already.

Dont forget to upgrade you main equipotential bonding, and supplymentary bonding in the bathroom.

Also, 10mm in thermal insualtion......tight.....I have no regs to hand at present, but think you may be borderline with that one.

 

[nabby68]

Thanks lectrician.
Circuit 7 has an mcb with (what i think , but not to sure) is and rcd built into it, as this has a neutral from the neural bar linking up with the two neutrals from the ring main which all go into the mcb/ rcd. will try and post a pic to help.
the 10mm will be run in conduit in the wall (plastered over) and then into loft space. by my tables, 10 mm run in conduit and thermal insulation is 46amps

 

[Lectrician]

Not sure by my tables.....they are at work.

Sounds like an RCBO used for your sockets. If the CU Isn't crouded, you could fit a second one for the shower. MEM do a 'pod' which fits to the top of the MCB's.

A pic would be good - on the older MEM boards, the busbars where wider, and the new, cheaper, breakers dont fit. Just beware of that.

 

[nabby68]

thanks lectrician.

MEM do a 'pod' which fits to the top of the MCB's.

yeah, i think thats what it is. what purpose does this exactly serve?

 

[nabby68]

leectrician also wrote:

A pic would be good - on the older MEM boards, the busbars where wider, and the new, cheaper, breakers dont fit. Just beware of that.

the cu is about 10 yrs old, so dont know if thats classed as an older one, but thanks for the advice.
i think i may go for the replacement cu option, and go for a split 12 way box. what do you think?

 

[Lectrician]

MEM do 10 or 14 way split loaders.

Go for MEM - best make around in my opinion. The breakers you have will fit the newer 2000 boards.

An RCBO would also be nearing the cost of an empty 10way split.

 

[Lectrician]

thanks lectrician.

MEM do a 'pod' which fits to the top of the MCB's.

yeah, i think thats what it is. what purpose does this exactly serve?

The RCOB is an MCB and RCD combined into one unit. Provides overcurrent protection via the MCB, and the RCD provides earth leakage protection. It is fairly common to see it done this way if only one circuit requires RCD Protection in a property.

 

[nabby68]

thanks lectrician.
so what is the "pod" on the mcb that you talk about in your previous post?

 

[Lectrician]

Look above Posted together

 

[nabby68]

beat me to it!

 

[nabby68]

but it does not have rcbo written on it? but i bow to your superior knowledge on this, so i guess coz i am installing a shower then best to get the sockets and shower on the rcd side, right?

 

[Lectrician]

Sockets that can "reasonably be expected to be used out of doors" must be protected by a 30mA RCD.

Sockets that get regularly used for handheld type equipment would be best protected by an RCD, although not actually required......oddly.

Sockets that will not be used for handheld equipment, or have no likely hood of being used outdoors are usually left without RCD protection (an office upstairs with plugs in behind desk.......)



A shower doesn't require an RCD to comply with the REGS, but my shower has one, and I think most other electricians showers would also be protected by one.......bare feet, soaking wet, close prosimity, and a relativly high current supply........umm. Foolish not to(in my opinion), but not a requirement.

 

[nabby68]

just been onto the mem website and found the rcbo/mcb you mentioned
never doubted your knowledge lectrician, thanks for your help and advice