13 Amp socket tolerances

[Old Codger]

:-)

[ARWadsworth]

It seems you are not that bothered.

[ARWadsworth]

He was too busy to apologise. she must have been looking up Nuremburg in the map book or putting out the fire he started when he tried to use an induction hob. Or maybe making anonymous calls to trading standards!

Or nursie gave her a nice colouring book to keep her entertained for the night and let the rest of us have some piece and quiet.

[ARWadsworth]

Claims to have!!!!!

In reallity he could not wipe his own arse.

[<me9]

Was it a ring circuit with part missing? I recently sorted out a ring with no continuity in a friend's house. A back box had been plastered over after first fixings, and a socket not fitted. This remained hidden for nigh on 50 years, and took some finding! He's now pleased with teh extra socket in the logical place for one on the landing, and it is now a ring.

No obvious problems showed up (or was the fault detected detected) in the intervening years, when its only protection was from a rewirable 30A fuse, now replaced by a 32A MCB.

[<me9]

But should be protacted as such, rather than as a ring with spurs.

[geoff]

In message , ARWadsworth writes

With an ASIC?

Its the only ring he has a clue about, and that's because he spends most of his time with his finger up it

[dennis]

The modern ones are significantly different, you can have lots of sockets on them, In fact they are more versatile than rings and cheaper to install. They have a better level of protection as they are 2.5 mm2 and have a more suitably rated 20A breaker. The IET introduced them to overcome some of the problems with rings.

No, the regs specify the minimum level of protection not the maximum.

Yes, it can and it can service a larger area . The area that can be serviced by a ring was reduced to stop electricians fitting large rings that are inherently less safe than smaller rings. (both subject to acceptable voltage drops)

Its one of those rules that have to be applied to make sure he rings are acceptable.

BTW it doesn't have to be a radial it can be a tree or anything else you like.

[ARWadsworth]

So it can be a banana then?

[dennis]

Its a spur on a ring! So what the hell have you been arguing about when you just stated its wrong to use a 32A breaker on 2.5 mm2 cable, ie. a spur on a ring.

[dennis]

You must be imagining it, other posters say these faults don't exist.

[dennis]

This is one of the big problems with rings, unless you actually go looking for the fault you just don't know its there and you can use it in a faulty state for decades. If you are lucky you will get away with it, if unlucky you don't.

[dennis]

Just because an electrician can read his book and quote bits doesn't mean he has a clue about what it means.

Adam can cite cases where rings have been faulty for decades and hence been essentially unprotected and still claim they are a good idea. But he does think its OK to ram cars too.

[John Rumm]

Of for that matter having a spur connected at the origin on a ring circuit.

[John Rumm]

As I alluded to in my post, there are a few specific circumstances where you could legitimately in effect feed a pair of radials from a higher rated MCB. This would be another case of splitting the responsibility for fault an overload protection. The 32A MCB will provide adequate fault protection to a single 2.5mm^2 cable, and then either a limited load or additional overload protection could be provided at the far end to protect the cables from individual overload.

Which suggests that this was a more common or garden variety c*ck up!

[John Rumm]

Makes you wonder how he tested that circuit after installation.

[John Rumm]

If we believe Dennis, there should have been a crater where the house used to stand! ;-)

[John Rumm]

You just said a circuit with a single cable... that can't be a ring dopey.

Now think it through. In exactly the same way that a spur is ok on a ring, it is also acceptable in certain circumstances to have a radial circuit where the MCB does not provide overload protection for the cable. It must however provide fault protection for it. A B32 MCB provides adequate fault protection for a single 2.5mm^2 cable as you well know.

[John Rumm]

Damn dennis, you should go into comedy!

How is a modern radial "significantly different" from an older one?

Prior to the introduction of the ring circuit, what circuit topology do you suppose was in common use - the pretzel?

Without seeing the installation that is impossible to say for sure. However its very likely to be untrue for ordinary socket circuits.

20A radials are a PITA in kitchens or anywhere with concentrated high load appliances (unless you like one circuit per socket - sometimes applicable for commercial kitches), so I assume you would want a 32A radial and 4mm^2 cable[1]. Unless the layout is particularly unusual, the 4mm^2 cable is highly unlikely to be cheaper than the small extra amount of 2.5mm^2 required to join the end of the ring back to the CU. Its also significantly more difficult to work with, and hence more expensive to install. [1] oh, and some 2.5mm^2 for the spurs from it! ;-)

I note you keep dodging the question about long term overloads on 20A radials (or any other for that matter). Exactly the same logic with which you attempt to sully the good reputation of other circuits, applies to these as well.

What was that circuit that pre-dates the introduction of rings again?

Perhaps you are thinking of broadcast power as suggested by Tesla?

So its just you then...

Wrong...

From table 8A OSG (pg 158)

For a 30 or 32A protected ring, max floor area serviced is 100m^2 For a 30 or 32A protected radial, 75m^2 For a 20A protected radial 50m^2

Have you considered writing children's stories?

A tree is a radial... radials can branch anywhere any number of times.

[John Rumm]

Banana's don't grow on trees...