GARAGE SUPPLY USING OLD CONSUMER UNIT ?

[cb12121]

hI,

I have just replaced my old MK RCD only consumer unit with a larger MK split load.
This now allows me to have a separate 'normal' feed to the outside , which is currently split via a junction box , to the garage and garden shed which are in the opposite directions. The garage contains freezer and flourescent light. and feeds one high energy outside sensor light plus several other bulkheads using low energy bulbs.
Can I use the old RCD unit for the garage and what rating MCB should I use to feed it, currently 16A, whereas the old units RCD switch is 80A.
Or, ( obviously but costly )is it best to get a proper garage unit ?

 

[baz1968]

Yes the old rcd can be reused as long as it is properly inspected and tested after installation and is good mechanical order.

The feeds to the garage and shed should be made in steel wire armoured and the protective devices for both will depend on the length of run, size of cable installed and total loading at both locations.

Under Part P these works are notifiable

 

[ColJack]

given your questions, I think I already know the answer to the next questions we all want to ask..

did you notify the LABC before you did this work?
did you test and inspect your installation after the board change?
Do you really think you will be able to do this correctly and safely if you have to ask these questions?

anyway, yes you can use the old RCD as it's rated to take 80A MAX.. that is not it's triping current, they are not for overload protection.

 

[cb12121]

Yes the old rcd can be reused as long as it is properly inspected and tested after installation and is good mechanical order.

The feeds to the garage and shed should be made in steel wire armoured and the protective devices for both will depend on the length of run, size of cable installed and total loading at both locations.

Under Part P these works are notifiable

Ok thanks for that.
Currently, the feed to the first outside junction box from the inside CU is via 2.5mm normal cable on a 16A MCB on the main switch. This joins at the first outside JB, with 10 foot of armoured 2.5mm cable to another outside JB, where the cable is split between garage feed and shed feed of approx 15 feet each using armoured 2.5mm cable.
I could obviously feed the lot via the inside RCD as before, but then someone pointed out that if I get a nuisance trip. the FREEZER goes off !!.
The only drain on the supply would be lights and mower , drill etc.
.. and yes I am fully aware of all the implications as I am the one plugging myself into the supply.. should that make my hair stand on end ??

 

[baz1968]

Its not just the implications of making your hair stand on end, it's the legal and health and safety implications. With the amount of work involved and the alteration/addition of these circuits you should really get a competent spark to look at all this. Your attention to detail on this project should be admired as most people would be happy that the lights work and the mower "mows" when plugged in but a qualified electrician is the answer here.

 

[cb12121]

Its not just the implications of making your hair stand on end, it's the legal and health and safety implications. With the amount of work involved and the alteration/addition of these circuits you should really get a competent spark to look at all this. Your attention to detail on this project should be admired as most people would be happy that the lights work and the mower "mows" when plugged in but a qualified electrician is the answer here.

Yeah Ok Thanks again.
When I moved in to this place, the outside was fed via a run of 1.5mm cable the full length of the loft, thru the soffit , over the archway, into the garage and into a Power socket.. all on the immersion feed

What I'm really asking here is....
How to best supply the freezer in the garage on a 'normal supply' whilst all the rest of the outside is via RCD. without having my local Dungeoness nuclear power station just supplying me.

 

[streetlighter]

The best way would be to get a new 4 way board for the garage with a switch disconnector incommer. The use an RCBO to supply the sockets and run the freezer of its own MCB making sure its hardwired into the supply with a means of isolation.
Mind with the main supply to the garage rated at 16 amps there may be some discrimination issues with the ratings of the MCBs in the garage.

 

[cb12121]

The best way would be to get a new 4 way board for the garage with a switch disconnector incommer. The use an RCBO to supply the sockets and run the freezer of its own MCB making sure its hardwired into the supply with a means of isolation.
Mind with the main supply to the garage rated at 16 amps there may be some discrimination issues with the ratings of the MCBs in the garage.

Ok, I was afraid someone would suggest something like that... its the cost you see and the hassle.. just for the freezer. I'm beginning to think the original owner had the right idea after all.
What If I just supplied the garage power points (inc freezer ) from the indoor CU Main side and the rest of the outside with another feed from the indoor RCD side.? I do now have spare outputs on the CU. Need to cover the wall with armoured cable tho. Yeah thats it .. why didn't I think of that

 

[securespark]

That way you still have the problem that if the garage circuit trips the RCD, you're goosed.

 

[cb12121]

That way you still have the problem that if the garage circuit trips the RCD, you're goosed.

Thanks guys

 

[dannyboi2003]

Simple solution here, don't bother using your old MK consumer unit as its overkill on the current supply you have to the garage. Simply mark the existing freezer socket as unsuitable for equipment used outdoors as its not RCD protected or change it for a switched FCU and hard wire the freezer to it. Then change the sockets in the shed to combined RCD ones, or if thats going to be expensive due to the number of sockets, re-wire them so the incoming supply goes to an FCU for the lights fused at 5amps then to another RCD FCU (not from the load side of the lights FCU obviously!) fused at 13amps to supply the sockets.

This would be better than fitting your old CU as you only have a supply fused at 16amps to the garage. I hope all i said makes sense and if you have any questions just let me know.

All the best
Dan