6mm Cable

[mjtefc9]

Hi all,

After some advice.

Got 6mm running to an outside socket as I knew we would be putting power in the shed... Am I okay to run the armoured from the socket now as originally that socket was only a adaptable box, in anticipation of the power to the shed.

Am I just over thinking it ‍

I'm an electrical trainee.

Thanks!

 

[ericmark]

Read this and this on loss of PEN then consider what you think.

The material used to build the shed may change what you think, and remember the first one is a bit out of date now.

 

[mjtefc9]

Read this and this on loss of PEN then consider what you think.

The material used to build the shed may change what you think, and remember the first one is a bit out of date now.

Thanks Eric..

It's on a 32a breaker in a spare way in an RCD protected board.. originally it was going to be 6mm armoured straight to a DB in the shed, but there is a socket before the shed now..

 

[JohnW2]

Thanks Eric..

It's on a 32a breaker in a spare way in an RCD protected board.. originally it was going to be 6mm armoured straight to a DB in the shed, but there is a socket before the shed now..

Having a break (at the position of the socket, whether that socket is kept or not) is not really an issue/problem.

I presume the potential issue eric was eluding to was the question of what you are going to do about earthing in the shed - export the house earth, have a local TT electrode at the shed or what?

Kind Regards, John

 

[mjtefc9]

Ahhh understand... I was planning on using the earth in the house DB

 

[Taylortwocities]

Ahhh understand... I was planning on using the earth in the house DB

What is your electric supply type?
What is the shed made of?
What services will be in the shed that might introduce an earth potential (water pipe etc)?

 

[mjtefc9]

What is your electric supply type?
What is the shed made of?
What services will be in the shed that might introduce an earth potential (water pipe etc)?

Thank you for replying,

TNC-S

Wooden shed and just two sockets and a light... No load at all apart from maybe a fridge.

No water or metal needing bonding

 

[Taylortwocities]

So should be no problem exporting the earth to the shed.
SWA he really doesn’t need RCD protection, but to u’ll need to keep the RCD at the origin because of the socket in the middle of the run.
You won’t therefore need another RCD at the shed end.
For two sockets and a light, just run your SWA in to the socket in the shed. You could spur to a ( 3amp) switched FCU as your light switch.

ISSUES
At the mid-run socket you are going to have to gland in both ends of the SWA.
I assume the existing SWA is properly glanded at the source end and the armour is earthed?
Earthing of the armour must be continued on to the new length of SWA.
You probably aren’t going to be able to stuff 2x 6mm into the socket terminals, so you’ll have the think how to do that.

 

[mjtefc9]

So should be no problem exporting the earth to the shed.
SWA he really doesn’t need RCD protection, but to u’ll need to keep the RCD at the origin because of the socket in the middle of the run.
You won’t therefore need another RCD at the shed end.
For two sockets and a light, just run your SWA in to the socket in the shed. You could spur to a ( 3amp) switched FCU as your light switch.

ISSUES
At the mid-run socket you are going to have to gland in both ends of the SWA.
I assume the existing SWA is properly glanded at the source end and the armour is earthed?
Earthing of the armour must be continued on to the new length of SWA.
You probably aren’t going to be able to stuff 2x 6mm into the socket terminals, so you’ll have the think how to do that.

Thank you so much for your help.

It's 6mm flex coming into the outside socket via back entry at the minute.. but I'll be okay earthing and terminating the SWA to the shed. Yeah think only issue I have is getting the extra 6mm into the socket terminals

 

[chivers67]

I'd lean towards using a small DB. I ran 10mm SWA to our Garden room and in the same trench I ran a Cat6 Screened cable for the Broadband (which works a treat).

The chaps that did the electrical work (as I couldn't sign off the work as not a Domestic electrician) fitted a 6 way contactum board with an RCD for the sockets and lighting circuits but there again it is quite big. It's probably over kill but it has an SPD too.

 

[JohnW2]

I'd lean towards using a small DB.

Many people would, but it's hard to see the real point (at least 'at present) for just two sockets and a light - particularly given that, as TTC has said, the existence of the socket in the run to the shed means that the circuit needs to be (as it is) RCD-protected at source- so no RCD needed in shed.

Is your 'leaning' related to 'future-proofing', or what? My view would be that if things evolve in the future such that a DB./CU in the shed might be worthwhile/needed, it could be installed then.

Kind Regards, John

 

[chivers67]

True, unless the Outside socket was changed to have a built in type. The existing one can be used on the outside of the shed?

 

[JohnW2]

True, unless the Outside socket was changed to have a built in type.

Yes, but why do that, given that the whole circuit is already RCD protected? Indeed, we know that the circuit is already RCD-protected, and it's quite possible that it's not a "high integrity" CU that has provision for any 'non-RCD' circuits.

In practical terms, even if there were some spare 'non-RCD' ways in the CU, shifting the circuit to there would probably be regarded by many as creating a 'new circuit', hence notifiable - with all the financial etc. implications of that!

The existing one can be used on the outside of the shed?

It could, or could be sold on eBay - but see above!

Kind Regards, John

 

[chivers67]

If the RCD trips up at the house you basically have to walk back to reset it that's my reasoning, I'd have it on a Time delay at the house if i was designing it personally with RCD at shed local to the installation.

Some will agree with that and others won't

Sounds very much like the OP ran it himself as a new circuit anyway. Is work to an outside installation notifiable these days or not?

 

[Taylortwocities]

If the RCD trips up at the house you basically have to walk back to reset it that's my reasoning, I'd have it on a Time delay at the house if i was designing it personally with RCD at shed local to the installation.

Some will agree with that and others won't

That doesn't fly though. The mid-garden socket MUST b e protected by a 30mA RCD. In your plan it would have a 100mA RCD. Not compliant.

Sounds very much like the OP ran it himself as a new circuit anyway. Is work to an outside installation notifiable these days or not?

Outside installation is no longer notifiable. Who made that decision??
However, a new circuit is!