Real Dummies question about mains electricity

[wanderer]

Could be a two phase or split phase supply.

The neutral should *never* be broken under normal circumstances. I know it will never happen (yeah, ok!) but if the neutral is broken, and the phase remains alive, yer average Joe Public DIYer won't necessarily bother to check with both a test lamp and a neon indicator - the leccy companies' approved way (1) - that the circuit is properly dead, They'll flick the switch, think the light's out so the circuit's dead, and bingo, it ain't. I know it's not a common scenario, and yer average DIYer of course always uses common sense (!) but a broken neutral can still be the cause of people dying.

(1) check the test lamp before switching off supply, then immediately test after switching off, then the neon to indicate if there's still a live on one of the conductors if the neutral has been broken.

[wanderer]

Why do you say that? Sorry, but I don't follow your argument.

One presumes a qualified electrician would recognise if the fuse carrier was faulty or damaged. Whether a DIYer would be competent so to do is another matter.

In either case the cutout fuse *is* the property of the leccy company and will be replaced by them if necessary. That doesn't alter the fact that there is an increasing tendency for DIYers and independent electricians to remove and replace the main fuse.

[wanderer]

Typical admd (after diversity maximum demand for a non-electric heating estate is only 1.5 to 2 kva, but quite a bit more for electric heating estates.

[:::Jerry::::]

But here we are not talking about 'normal circumstances', but when work needs to be carried out on the meter tails etc.

I know

It would only become broken if purposely removed, unless there is a substantial overload (which would cause many other problems to say the least...) how would a solid steel busbar link ever fail.

[wanderer]

Yep, no problem with that. If you read my reply in context I was answering the question about why isn't there a neutral link. It does, of course, assume that whoever is doing the work is competent so to do.

[Alan]

In message , nightjar wrote

I watched the electricity board employee replace my meter with the tails 'live' - no gloves.

[nightjar]

Perhaps I should also warn people to stay away from water. It kills about as many people each year as distribution voltage electricity. Possibly they should stay off pavements too, which kill about half as many. As it happens, you were particularly unlucky. Skin resistance is normally high enough to limit the current from 230v electricity to non-fatal levels. There usually needs to be another factor, standing in water, sweaty hands etc., before the current reaches potentially fatal levels. 230v is not particularly dangerous, either by comparison to other voltages or as a cause of death in the UK, but I didn't say it was safe.

...

That is simply nonsense. Electricity is not a bacterium and repeated exposure does not produce immunity. At distribution voltage levels, either the current falls within one of two, fairly narrow, bands or it does not. If all you feel is a jolt, the either the current was not within either fatal band or it did not pass through the chest.

Colin Bignell

[a]

Here is a picture of my incoming fuse(s)

here is a picture of the incoming cables - I dont really like the look of that earth connection

[Lurch]

On Sat, 14 Aug 2004 12:21:02 +0100, "a" strung together this:

the neutral side. Of course, it might not be but that's what they usually are.

[Richard Savage]

Ditto, but it was the company fuse carrier that they replaced. Bare handed, the bod hammered the old fuse carrier and its pitch insulation off the end of the live incomer. As he exposed the live conductor he slipped what can only be descibed as a small red condom onto the bare wire. Once enough cable was exposed he slid the bare neutral and live into the new fuse carrier and screwed everything up. Simple as that. And yes he had both a friend watching and shoes with very thick soles, but trousers with, apparently, ordinary thickness knee fabric!

TTFN

Richard

[Owain]

"a" wrote | Here is a picture of my incoming fuse(s) |

you appear to have here is a supply cable looped into your service cutout and then looped out to a neighbour. This was not uncommon in some parts of the country at one time. In which case the fuses are most likely a fuse on the phase (left, judging by the red tape on the meter tail) and a link on the neutral.

| And here is a picture of the incoming cables - I dont really like | the lookof that earth connection |

would be pre-1970-something when green-and-yellow became mandatory for earthing. There should also be a Safety Electrical Earth Do Not Remove tag on the connection. However it looks reasonably safe. The paper seals on the fuses look fairly recent too, not that that necessarily means much.

I would be more worried by that thin grey? bare painted? wire down by the skirting, and the grey cable by the bottom left insulator.

Owain

[Mike James]

"nightjar .uk.com>"

[Lurch]

On Sat, 14 Aug 2004 14:46:37 +0100, "Owain" strung together this:

It still is quite common on new supplies too.

[troubleinstore]

Usually 2 houses per supply cable

-- troubleinstore

mail can be sent via website. Email address in posting is ficticious and is intended as spam trap

[IMM]

You don't know much do you?

[Grunff]

Indeed - I must remember to prefix all my IMM replies with "in our universe..." - just smetimes I forget, you know?

[IMM]

Whoes universe are you on about?

[raden]

In message , IMM writes

I think he was working to real world physics, not the ones you make up as you go along.

The current a 12 volt battery (or any other source) can deliver is limited by the resistance of whatever it's supplying.

Go away and do some maths (clue - V=IR)

[IMM]

Maxie, don't be silly, go ohm.

[Andy Dingley]

In the USA, there's a lucrative business in landing helicopters in contact with on the hot side of power lines (with the aid of a great big resistor on a stick) while a guy in such a suit pressure-washes the insulators clean.

like spacehoppers, I tell you....