Garage upgrade

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Petegft

Member
Joined
Aug 14, 2018
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Location
Warrington
Hi I'm new to this forum and this is my first post!

My question is; I live in a Bungalow which is almost forty years old and in the outdoor enclosure where my meter is there is a Rusty Wylex  106 isolator and 20amp fuse this feeds a two core 2.5mm SWA Cable which runs approx. 20mtrs? I assume it was installed when the house was built as it goes down between the brick wall and presumably underground and then surfaces through the concrete floor within my Garage and rising up the wall a metre . The SWA then enters another Rusty Wylex Box with a ten amp fuse in with a T&E 2.5mm cable exiting to go across the Garage roof to an FCU which currently feeds one single socket and one single socket with an RCD on and, the lights which are two florescent tubes five foot long! 

I moved in this Bungalow six years ago and at the time I had intended to upgrade the Electrics and bought a new Garage CU with RCD and round plastic Conduit and the relevant fittings!

Having retired now from my job as a Mechanical Engineer I have decided to complete these outstanding works! I asked my Electrician friend to pop round and go over my proposals with me to ensure what was planned would be safe and in order!

At the distribution Board the SWA is branched from the meter Tails and independent of the House CU. My friend has suggested installing a small enclosure with an RCD rated at 100ma and an MCB rated at 20amps to replace the Rusty Wylex? In the Garage would be the new CU which is rated at 30ma and I've downsized the original MCB from 32amps to 16amps plus the 6amp MCB for the lights!

I've followed my friends advise and installed three 2 gang sockets and one outdoor 2 gang socket on a Radial Circuit all cables are enclosed in round plastic Conduit! I've also fitted the Conduit to facilitate the conversion to a Ring Circuit should that be required in the future?

Here now is my question (Fanfare) Is my friend correct and is it necessary to have an RCD at the distribution Board which really is only protecting a 2.5mm SWA Cable which has been buried and flagged over for Forty Years? Could it not just be an Isolator with a 20amp MCB ?

Hope this is not too draw out, thanks in advance,

Petegft  

 
I would recommend a 30mA RCD in garage, either an RCBO for the socket cct or install an RCD protected socket at the outdoor unit, ie the socket most likely to be used for a portable appliance outdoors.

 
In my opinion you don't need the 100mA  at the mains end  as its a sub-main  and it's not buried in the walls of the house .

Others may (and probably will)  disagree but I'd just fit your enclosure  with a DP isolating switch and a 20A MCB .

Then a  2 or 3 way  garage board  with a 30mA  main switch  along with  your 16 & 6A  MCBs .   

 
In my opinion you don't need the 100mA  at the mains end  as its a sub-main  and it's not buried in the walls of the house .

Others may (and probably will)  disagree but I'd just fit your enclosure  with a DP isolating switch and a 20A MCB .

Then a  2 or 3 way  garage board  with a 30mA  main switch  along with  your 16 & 6A  MCBs .   
Thanks for your reply that concurs with my theory too, hopefully someone else may reply and confirm our theory !

I don’t want to upset my friend as you know how tempremtal Electricians can be 😀 (only joking 😉)

petegft

 
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