Educate me...

[JohnW2]

If I was working in the shed (if I could have one - but I cannot) and I tripped a breaker etc. then I would be really pi$$ed off having to go back into the house in order to reset it.

A lot of people seem to say that, which makes me wonder whether they are all perhaps experts in "blue moons".

Exactly how often do you (or 'they') think that anything happening in a shed (or any other outhouse) is likely to trip a breaker anywhere? I 'have electricity' in a garage, a greenhouse, a (cellar) workshop and a couple of sheds and I don't think I can recall, in 30+ years, anything happening in any of those places which resulted in any device, anywhere, 'tripping' (except when 'deliberately', in the name of testing etc.).

The best reason to have a CU in the shed/garage/workshop IMO.

Of course, even that will not usually (depending on how it's done) guarantee that nothing in the house will 'trip' (or 'blow') as well as, or instead of, whatever trips in the outhouse.

Kind Regards, John

 

[SUNRAY]

In 1966 we built a garage, fed it with 7/0.029 on a 15A fuse (wire) since then the fuse has blown twice, first time a fan heater and 800W of lights didn't leave enough to run a 140A arc welder, second time a fence replacement chopped the cable (T&E buried in a 1" plastic duct, I suspect water pipe). Before that a 3/0.029 was added to a bedroom socket and suspended to a brick shed <6ft from house, a 10A fuse in the shed blew just the once by a faulty appliance and damage to the feed cable blew the bedroom radial fuse. The 15A feed to the greenhouse never blew but an RCD likely would have when water dripped into a heater.
All totally as expected. However the use of all 3 buildings has always been very light, a workshop in daily use with power tools potentially has greater chance of tripping.

All were rewired when I lost my parents mid 90's with 32A radials, garage has buried SWA, shed in PVC conduit to a CU, greenhouse has 16A radial from there with T&E in 32mm plastic duct buried in concrete path.

Since then the property has been rented out. I'm not aware of any problems since.

At home I have 2 outbuilding and no trips since 1994 other than chopped lawnmower cable.

I don't think there's much of a risk of problems.

 

[Munroast]

If you have a ring circuit 50 metres in length, and you place a 13A load 1 meter from the source, how much currant will be in the 49m section ?

2% of 13A.

that certainly is the logical answer - but would the reality be 50% ?

 

[EFLImpudence]

No.

It's not logic. It's physics.

 

[Munroast]

No.

It's not logic. It's physics.

how sure are you ?

 

[JohnW2]

how sure are you ?

Hopefully he's as sure as I am, since we are both probably subject to the same Laws of Physics!

Kind Regards, John

 

[SUNRAY]

If you have a ring circuit 50 metres in length, and you place a 13A load 1 meter from the source, how much currant will be in the 49m section ?

I looked at a 32A socket for a welder and initially struggled with the reason one of the 2.5 t&e's was showing signs of overheating but the other was not. This was in a domestic property with a ring covering the whole house [apart from the kitchen] including the garage which was being used as a workshop for metal fabrication. This 32A socket [yellow of course] was less than 2m from the CU. The house was running at around 16A or so when I clamped and the welder around 40A with peaks over 200A [limit of meter], most of the welder current appeared in the short leg of the ring at around 45A. MCB had been changed to D32 to prevent 'false tripping'.
Owner suggested changing the leg of the ring to 6mm² which he had there. I suggested removing said socket from the ring and running it on the spare 40A MCB labelled 'shower'. Following on from there we changed it to C40 and changed socket to 63A isolator.

From https://www.diynot.com/diy/threads/...s-is-this-good-pic.483672/page-9#post-3927461