Separate circuit direct from supply to bypass main CU

[MFRacing]

Hi guys,

My CU (Split - RCD protected) is in my garage which has an electric door, so when the main CU trips I can't open the door electronically which is a pain as I need to get in the garage to reset the trip!

So what I want is a separate 1 gang CU that takes it supply direct from the incoming supply and is totally separate from the main CU, which will then be only used to power the garage door. So this means when the house CU trips, the garage door will still be powered on the separate supply.

Now can I just open up my main CU, find the incoming supply cables and run a new cable from them to supply a new separate new CU box? My main CU has a main switch in the outside box so I can safely isolate the main CU supply side while working on it.

Any advice, tips etc? I'd like to do the work as much as I can as i've done plenty of electrical work before and have multimeters etc.

Thanks

 

[Adam_151]

Does your CU not have any spare none-RCD ways? Picture?

Doubling up off the main switch terminals is not ideal, you can easily end up witha poor connection if you are not careful, better to split with henley blocks.

Notifiable work, also

 

[EFLImpudence]

Now can I just open up my main CU, find the incoming supply cables and run a new cable from them to supply a new separate new CU box?

Take the supply from the Main Switch load side (bottom) so that the switch also switches off the new circuit.


...and - be careful.

 

[MFRacing]

Does your CU not have any spare none-RCD ways? Picture?

Doubling up off the main switch terminals is not ideal, you can easily end up witha poor connection if you are not careful, better to split with henley blocks.

Notifiable work, also

It does have spare ways but Im assuming everything goes through the RCDs? Could I add a new MCB that is not protected by the RCD/Main switch in there?

 

[MFRacing]

Take the supply from the Main Switch load side (bottom) so that the switch also switches off the new circuit.


...and - be careful.

Yer i was thinking that. So just add my new cables to the supply side of the main switch? That ok to do?

Will be careful, checking for dead and turned off at main switch before CU in the outside box.

 

[Adam_151]

Can we have a picture of your CU?. Ideally without cover as well (switch off with isolator in meter box before removing cover, and don't turn back on until it is refitted)

 

[endecotp]

So just add my new cables to the supply side of the main switch? That ok to do?

No No No


by which I mean:

NO, do not connect your cables to the main switch - you need an MCB.
NO, do not connect anything to the supply side of the main switch.
NO, don’t do any of this yourself; your posts demonstrate a lack of sufficient understanding to do this safely, even with help from the forum.

 

[MFRacing]

Can we have a picture of your CU?. Ideally without cover as well (switch off with isolator in meter box before removing cover, and don't turn back on until it is refitted)

Yep can get one in the morning for you

 

[MFRacing]

No No No


by which I mean:

NO, do not connect your cables to the main switch - you need an MCB.
NO, do not connect anything to the supply side of the main switch.
NO, don’t do any of this yourself; your posts demonstrate a lack of sufficient understanding to do this safely, even with help from the forum.

Thanks but I think I can do it safely.

 

[EFLImpudence]

So just add my new cables to the supply side of the main switch? That ok to do?

No, I said the load side.

 

[MFRacing]

No, I said the load side.

But then when main switch trips I will lose power to garage door. I want to stop that happening.

 

[EFLImpudence]

Main Switches don't trip - perhaps Endecotp is right.

 

[MFRacing]

Min Switches don't trip - perhaps Endecotp is right.

Mine always trips when the RCD trips. Always together.

 

[EFLImpudence]

Then something is not right.

Picture please. Just copy and paste or drag.

 

[MFRacing]

No problem. Will get pic in morning for you.

It’s very rare it trips but just a massive pain when it does.