bulb fittings ES or BC

[charles]

We had 12v ES emergency lights in our theatre. They used quite standard ES theads. Confused some people sometimes.

[sm_jamieson]

I've ordered some now. But yes that is a very good point. I think when I use them I will take steps to ensure they are connected the safer way round. Its certainly easier to touch that outer thread than the bayonet pins.

I have both types of light fittings (largely due to Ikea) and both types of bulbs (due to whatever affordable/decent LEDs or CFLs were available), so interoperability is helpful.

Simon. Simon.

[cl]

Yes, I believe it was basically a copper saving idea in the post 2nd war years.

Personally I think the disadvantages outweigh the advantages, I always install 20 amp MCB radial circuits in preference to ring circuits.

[charles]

Some years ago a friend bought house which was wired that way. The distribution board was big enough for a small factory.

[Huge]

The distribution board in my mother's tiny 3 bed semi in America was about a square yard. And incredibly ugly and made very cheaply from painted pressed steel. It was in a wall in the kitchen. They hung a poster over it.

[cl]

You don't need many more MCBs, it's not like the continental system where there is one MCB per circuit. The IEE 'rules' suggest a maximum floor area per MCB with no specific limit to the number of sockets per MCB. Basically you'd need two 20 amp MCB circuits to provide sockets to the same sort of area that would be served by one 32 amp ring circuit. The major advantage is that you never have to puzzle out whether any particular socket is a spur off a ring or not and you can't suffer from a 'broken ring' fault.

[Tim Watts]

I claim the opposite view - particularly in kitchens, having it not matter too much how you plug those 3-4 high power appliances in makes having a 32A circuit quite sensible.

[Chris French]

In message , charles writes

It's negotiated between the host and the device.

AIUI, the device can request higher voltage or current, presumably it defaults to 5V.

[jack]

It only supplys 24v when the device says it can handle that. It initially supplies only 5v and that is the voltage the negotiation is done at.

[Tim Streater]

In the US, larger appliances will be at 240V and have different plugs. I had one when I lived there. None of the US or continental plugs are fused.

[Dave Plowman (News)]

The size of the plug isn't generally important within reason.

Right. So double the chance of having sockets where you don't need/want them. And equally not where you do.

Given a 12v 1 amp supply fits in a wall wart which plugs into the ring, I can't see any advantage in this at all. But lots of disadvantages.

If there is you can just about guarantee it will be worse than our current one.

[Dave Plowman (News)]

Why would you 'puzzle' about that?

A radial circuit never breaks?

[Mike Tomlinson]

En el artículo , Tim Streater escribió:

+2

[Alan Braggins]

If a radial circuit breaks, it's obvious. If a ring breaks, it becomes two radials which can appear to work fine, but no longer share load:

[Mike Tomlinson]

En el artículo , [e-mail] escribió:

Welcome to the 20th century.

[tabbypurr]

Have you never seen the 2 pin shutters? They aren't earth pin operated.

No, USB delivers 5v until greater voltage has been negotiated. It works, but means a mass of power control chips are needed. Maybe it really is cheaper than adding an extra contact in the lead.

NT

[tabbypurr]

Ring circuits are almost all upsides compared to radials. There's not much contest.

NT

[tabbypurr]

No, instead of an almost trivial broken ring you get a fire or dead or unearthed sockets.

NT

[tabbypurr]

At £8 a plug the 20th century can wait. Once it's out of patent maybe.

NT

[Jeff Layman]

I asked the same thing in the newsgroup 18 months ago. Doesn't look like much has changed.