Two 2.5mmT&E to a garage?

[MacGyvover]

I’m getting conflicting advice. Can anyone steer me to the correct answer please?

Situation: a small shed/garage with an electricity supply from a landlord. It’s close to the main building. A separate standing charge is paid, which is nuts.
A little while ago, during refurbishment works in the main building, we told the electricians that we would in due course want to run the shed off the main building CU.
A dedicated pair of 2.5mm T&E cables were run from the CU location to the edge of the building, about 4m from the shed, for later connection.
A 6mm SWA cable has now been run from the shed to the pair of 2.5mm T&E.

Another electrician has said one ought not to use both 2.5mm cables, only one. In case one fails and you wouldn’t know.

The loads in the shed would be low: a washing machine and lighting. Occasionally power tools. 99% of the time, zero load.

If one were to connect a 13A socket to the pair of 2.5mm cables, surely it would be a ring final? So why are we being told not to do essentially that, but with a 6mm cable going to a small CU?

I’m flummoxed!

 

[flameport]

A 6mm SWA cable has now been run from the shed to the pair of 2.5mm T&E.

An unusual choice but could still be compliant. A 32A circuit presumably?

Another electrician has said one ought not to use both 2.5mm cables, only one. In case one fails and you wouldn’t know.

Nonsense. With thinking like that, nothing would ever be installed anywhere.

 

[ericmark]

I used twin 150 mm² instead of a single 240 mm² as I could not physically bend the 240 mm² to fit. I see no difference with smaller cables.

 

[AndyPRK]

Swa 3 core or more?

 

[ebee]

Another electrician has said one ought not to use both 2.5mm cables, only one. In case one fails and you wouldn’t know.

The mind boggles!

Ask that electrician if any radial circuit is run and if one fault such as a break in the cpc that might that mean the possibility of an earth fault on one appliance could become an earth fault on several appliances whereas with parallel conductors that one break in one earthwire might be mitigated by the presence of another earthwire (such as one present in a ring final circuit for example).


Regular testing of earth continuity is important but we are all aware that it is not usually done as often as it should be, similarly we all know that RCDs might have a better chance these days because there are more RCDs connected compared to the number in use a few years back but we try to avoid reliance unless its a TT system anyway.

 

[MacGyvover]

Thank you for the responses, apologies for my tardy reply! It's "that time of year".

The message I've gone away with is: push back.

It's 6mm three core SWA, the total length is not more than 10m. The total length of the pair of 2.5mm T&E is no more than 25m.

As noted above, how would anything ever get done if every electrician had attitudes like that!

Thanks again for the helpful input and replies, much appreciated.

 

[Mottie]

I have a single 2.5mm cable going to my garage at home. Just runs lights and the odd power tool but it also carries on to our shed where it powers lighting, a freezer and a tumble drier. Been like that for 30 odd years with no problem.

 

[ebee]

I have a single 2.5mm cable going to my garage at home. Just runs lights and the odd power tool but it also carries on to our shed where it powers lighting, a freezer and a tumble drier. Been like that for 30 odd years with no problem.

Can I just point out that just because that happens it does not, in itself, prove compliance or safety.
There are many things that might not comply or not be considered “safe” that might well work without any discernible problems.
Example - you might drive around for years in a car that many would describe as a “death trap” and the fact that no one has actually experienced such problems with it does not mean that that (loose) description is so very wrong does it?