All Done by Electricity 1968

[Andrew]

I still have one of those useful adapters in my box of electrical oddd'n'ends. The 45 degree spur also has an on-off switch, for 'safety'.

[Andrew]

Isn't there a limit on the number of sockets allowed on a ring main, or is it just the area served ?.

[Andrew]

I was watching Gloria Honey**** on BBC1 at 11AM presenting a progam on how to live longer.

They were asking a group of Centenians what they did to get to that ripe old age and one old bloke said 'Avoid Turnip like the plague'.

Indeed.

[Andrew]

If you have a complete comb-over, as the presenter has, how does your hair stand on end after a shock ?.

[Terry Casey]

Yes, rather atupid place for a conector. Captive mains leads today are much better.

However, the basic connector you described, although physically very different, worked in the same way as the Schuko connector used in most European countries.

[Terry Casey]

Yes - the CLIX connector.

This would be back in the days when most TV sets had a fixed

5A 2Pin connector on the back and a mains lead with a flying 2pin 5A female flex connector. All our soldering irons had 5A 2pin male connectors to suit (earth not connected!)

Yes, erxcellent for anything not fitted with a plug.

[Terry Casey]

Don't remember nylon ones but you are wrong about the cord grip. Not the screwed type as found on 13A plugs, I'll grant you but the same method as used on BC light lockets, if correctly fitted. The insulated conductors were looped around moulded hooks and were very secure.

Visualise a hefty glass lamp shade and bulb with a BC connector dangling on the end of a bit of flex.

They didn't keep crashing to the floor did they? (If correctly fitted, of course.) They were a lot stronger than you think!

Don't remember ever seeing anything like that. (I'm pleased to say!)

[Harry Bloomfield, Esq.]

Andrew wrote on 30/07/2019 :

Area..

[stephenten]

Well I do have six ring mains in this house....

Kitchen and utility Lounge and master bedroom Dining room and bedroom above it

3rd reception room and dormer bedroom and office Loft sockets Outside sockets.

I don't think there is a limit on the number of sockets on a ring main, but I think there is a maximum area limit of 100m2.

In any case, you do have to think about the prospective loads on the ring main which is why there is a ring main dedicated to the kitchen and utility room.

The outside sockets are on their own RCBO so that if anything happens outside, it does not affect anything in the house.

The loft ring main is on account of the computer equipment and TV/radio headend & multiswitches.

[tabbypurr]

that certainly was not my experience. Sure they had an excuse for a cordgrip, but it was hopeless. There was more than one type you know.

I don't recall giving any indication of how strong I thought those were. They don't crash down because people are seldom fool enough to overload them. I've certainly had luninaires that would have no chance of being supported by those loopy roses.

I only ever had one, refused to use it. It had no clamping force holding the conductor against the prong at all. And of course no cordgrip, earth, polarity or fuse.

NT

[Andy Burns]

With that many rings, serving one or two rooms each, is there an argument to just make them radials instead?

[Harry Bloomfield, Esq.]

[e-mail] expressed precisely :

We had several of them and the cord grip was just like the hook cord grip of a lampholder and most ceilng roses.

To fit one, you unscrewed the top cover, push the two brass 'split pins' up through the base a little way, then inserted the bared flex ends. Finally, clip the flex onto the molded hooks and screw the top cover back on, which action, tightened the 'split pins' onto the flex. Tightening the cover, it would make a slight clicking, which would help stop it self undoing.

[stephenten]

The rings also support high integrity earthing and the sockets have two earth terminals each... This precludes the use of a radial.....

[stephenten]

And not only that, a radial is only rated to 20a whereas a ring main is rated to 32a which is a better choice for high load areas like a kitchen or the loft it and headend/multiswitches

[Andy Burns]

I could understand either a 32A ring (or 4mm^2 radial) for kitchen/utility, but high current for TV kit?

I thought high integrity earthing was only required where multiple appliances with greater than 10mA leakage were expected?

[bert]

Still got some and much later than 70s - and no-one has been killed so perhaps you meant potentially lethal. In article <qhoors$9ee$ [e-mail], Brian Gaff [e-mail]> writes

[Bob Eager]

Is there not also a limit on length?

[stephenten]

I thought so too particularly with:

1. Ensuring that voltage drop along L and N was less than 4% of supply voltage at maximum design current of the ring final circuit at the furthest most socket to the RCD/RCBO.

1. achieving below a maximum earth loop impedance to guarantee the required trip performance of the RCD or RCBO.

I have never seen a stated limit on the cable length, only on area.

As there is no stated limit on volume, in theory you could have a ten story house with a footprint of 100m2 and wire all ten rooms sockets all on one ring main(!).

Hopefully Adam will be along to comment further.....

[Steve Walker]

I have always presumed that the area of each floor served was added up, not just the single footprint.

SteveW

[Swer]

Could be useful for emergency fan heaters on boiler failure.