Metalclad CU

[m4tty]

Hi,

Im going to change my fuseboard at home. At the moment i have a metal wylex cu with mcbs (no rcd). The maisonette i live in is on one floor and concrete construction with all wiring in metal conduit. Metal conduit is earth for circuts so just Line & Neutral cables to sockets and lighting.

Here is a picture of the current fuseboard. I believe the conduits are glanded to the metal cabinet and the metal board is earthed through the screws??

http://i1201.photobucket.com/albums/bb346/m4ttyd/IMG_1285.jpg

I have bought an insulated wylex 10 way board but wanted to know if this has to be replaced with another metalclad board.

My pal who lives upstairs has had his fuseboard replaced with an insulated one so wonder if his has been done wrong or can i replace with insulated?

Thanks in advance

Matt

 

[Zeespark]

So long as the knock out holes match up Matty, there shouldn't be an issue. Are your circuit cables singles or T+E mate?

AndyGuinness

 

[SparkyMarky]

If, as you say, the conduit is the cpc then you must ensure continuity to the MET which was previously supplied by the metal CU.

 

[steptoe]

metal trunking with a suitable CPC to new cu?

personally I never do these (in domestic) without a complete rewire of affected circuits.

 

[Zeespark]

Steps, I was going to suggest installing independent CPC's at the minimum depending on IR readings.

AndyGuinness

 

[m4tty]

It all tests out fine. It's only the ring and the lighting which is installed in singles using conduit as earth but ring covers most of flat. What would yOu put down for ring circuit continuity for earth (conduit). How would you earth the metal case to met. Fit a metal met to the metal case and run a 10mm to earth terminal in cu?

Thanks for comments so far

 

[Zeespark]

Just install a 2.5 G/Y single mate, it would sort all of those issues out.

AndyGuinness

 

[Evans Electric]

M4ty , are the conduits bushed into that metal cabinet or into the board itself ?

 

[steptoe]

could you cut the metal piece out that the conduits connect to?

leave them bushed onto it, (bit of 10mm earth to earthing terminal), enclose them in a piece of 4"X4" trunking (or maybe even 2"X2") and then into your plastic cu?

probably mean all the cables being short though...

---------- Post Auto-Merged at 21:00 ---------- Previous post was made at 20:57 ----------

right,

just had a look at the pic,

as with Deke,

are the conduits earthed to the cabinet, or the cu?

if its the cabinet then yes, why not lug it and take(even) a 16mm earth to the MET,

would work for me.

on your EIC for cpc size simply put down mechanical, but your cable definition will show this anyway.

 

[m4tty]

Right I've just emptied the cupboard and the board is mounted on some fiberboard and the conduits have bs951 clamps around them and connected to the met using 4mm. Do you recon I should upgrade these to 10mm ? Thanks and sorry for the confusion cheers

 

[Evans Electric]

4mm seems fine to me for earthing the conduits.

On your pic it looks like the conduit is made off into that metal cabinet with T/E coming out of it into the board .

Your metalclad board is OK , just grommett the K/Os .

 

[m4tty]

4mm seems fine to me for earthing the conduits.On your pic it looks like the conduit is made off into that metal cabinet with T/E coming out of it into the board .

Your metalclad board is OK , just grommett the K/Os .

Cheers Deke, that conduit is made off into the top of the metal cabinet and runs upto the immersion heater switch then to timer then to immersion. Ive taken a few pics to show you what i mean.

The metalclad board is going and is being replaced with an insulated wylex dual rcd board (for assessment). I was a bit worried that i needed another metalclad board.

Wonder why a metalclad board was installed here int he first place ??

What is the metal cabinet called? and was it installed because the immersion heater is directly above it so if it leaks the board wont get wet?

Cheers in advance

Matty

 

[andy_spark]

When was the property built? Was it a former MOD property? This may explain why. Some houses and blocks of flats of these types were wired with steel conduits, especially those built around 1960s.

Don't forget to make sure IR resistance is good for circuits as any damaged cable in conduit can be a big nuisance when it comes to a fault that causes tripping.

 

[m4tty]

Cheers Andy. It was built in 1974 as a council block but has all been sold off now so all private. All ir tests out fine mate thanks

 

[andy_spark]

I thought it might have been.

I see it often and as I'm sub-contracting for local housing association, I replace these metalclad boards everyday and making sure the knockouts line up is the hardest part, old MEM boards trying to line up with new Wylex etc...

Many council flats were re-wired circa 1990 and now fortunately have T&E using the conduits. I still have to ensure conduits are earthed and everybody seems fairly happy if 6mm Earth used to bonding clamps on conduit, I think this is the required size in 17th regs.