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R C Ds

In article , N. Thornton writes

Why?....

Reply to
tony sayer
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Because very few people are killed or injured from faults in the lighting circuit, whilst loads of people are killed or injured when the lights go out unexpectedly when in a dangerous position, or they can't find their way out in a fire which has caused a whole house RCD to trip, taking out the lighting.

Christian.

Reply to
Christian McArdle

I'm glad it's not just me.;-)

I think I know most of the arguments for and against, but surely the

*only* point in an RCD is to protect from electrocution? And it's far easier to contact live parts when changing a bulb etc than when plugging something in to a ring main?
Reply to
Dave Plowman (News)

In article , Christian McArdle writes

Well I've known and heard of more incidents with lights and electric shock then lights tripping in a house fire. But I suppose your mileage may differ.

And I wonder what the changes of a house fire tripping the RCD is unless the RCD tripped before the house fire started?.....

Reply to
tony sayer

The design of lighting sockets means that it is very difficult to get much more than embarassment from the attendent shock of sticking your fingers in.

Quite high when the fire starts burning through the cable insulation.

Christian.

Reply to
Christian McArdle

Which then throws you off the ladder...

Reply to
Dave Plowman (News)

If you're that worried, at least wire the lighting circuit off an RCBO, so that a fault on a different circuit doesn't take out the lights. The recommendation is no RCD at all, except for 100mA protection when using TT earthing.

The RCD doesn't only protect against electrocution. It also protects against fire by cutting power to leaky circuits that might be causing considerable localised heating at the point of failure.

Christian.

Reply to
Christian McArdle

... but the chances of contacting live parts *and* being well earthed at the same time are very small. If you stick your finger in the lamp holder then you'll get a shock because your finger is between live and neutral, this *won't* trip an RCD.

In the case of table lamps etc. they'll most probably be on the ring main which is RCD protected, with these you are more likely to be touching earth when you change a bulb.

The only 'in between' case I can think of is wall lights where I suppose there is a greater chance of touching something earthy at the same time as you change a bulb.

Reply to
usenet

In article , Dave Plowman (News) writes

More like when the avid D-I-Y'er is working.

Well this place is all on one 30ma RCD and its staying that way until such time as I get A roundtuit with the RCBO's etc.....

Reply to
tony sayer

In article , Christian McArdle writes

Quite....

Reply to
tony sayer

You stick your finger in a lampholder that accurately?

Mine are all off the lighting circuits as they're switched from a convenient wall switch and or dimmer.

Reply to
Dave Plowman (News)

In the dark and don't forget that the few mS after the lights go out your eyes are well stopped down as well... So you probably won't see the side of the dresser or table heading at relatively medium velocity for your head...

On the fire side I guess it depends where the fire starts. In a room it's going to be quite intense before the fixed wiring gets damaged enough. Flexes how ever may well fail earlier and remember that the conductors might not have to touch anything as the flames and associated ionisation may well be able to draw enough leakage current from the bare wire to trip an RCD.

Another way around the "lights out" in a fire problem could be to fit non-maintained(*) lighting at key points fed from the lighting circuit but remember they generally only have a 3hr run time.

(*)The confusing term for lights that come on when the power fails. "Maintained" lights are on all the time irrespective of the main power status.

Reply to
Dave Liquorice

Most lampholders don't have any earthed parts so you don't have to be accurate at all!

Reply to
usenet

Never any visitors, helpers or trades people?

Are your light sockets live when switched off?

He he, unlike up here where a cloudy night is absolutely, completely and utterly dark, with the possible small exception for a week or two around midsummers day. Even then it would be pitch black inside most of the house apart from the north facing rooms.

But you have only been "detecting" serious overloads in the past not small leakages. That immersion that failed may well have started to cause the odd RCD trip for quite a period before it failed short. OK the immersion is not RCD protected but it serves to illustrate.

This is probably the best way to go but RCBOs aren't cheap...

Reply to
Dave Liquorice

That's the best solution, but not cheap. It is done using RCBOs, which combine the RCD functionality with the MCB. I use them in my installation, but many would baulk at the cost.

Christian.

Reply to
Christian McArdle

Hi,

Would it be acceptable to use a dedicated garage consumer unit to feed the lights and fridge/freezer?

cheers, Pete.

Reply to
Pete C

On Thu, 26 Aug 2004 15:24:52 +0100 (BST), "Dave Liquorice" strung together this:

3hrs at fullish brightness, they usually last more than twice until the light level becomes unusable, by which time you should have found your way out and called the fire brigade so "only 3hrs" is a bit of a something or other, not sure what, possibly daft term, but in a cleverer word.

Well, no actually. Maintained emergency lights are switched on and off with either the local lighting or with a dedicated switch but will illuminate when the power fails irrespective of the position of the switch.

Reply to
Lurch

Useful information that. I always take marketing information with a large pinch of salt. So "Runtime: 3hrs" I read to be 3hrs with new NiCds after a few cycles to bring 'em up to full capacity, to the point where the invertor drops out due to lack of volts, useable light having stopped being produced after 2 hours at the very most"...

My useage would be safety, as in not falling down the stairs during a power cut. Ideally I need runtime for a whole midwinter night or approx 16hrs.

So what are the ones that cannot be switched off, by the user, at all called?

The back of the now rather old CEF cat produces the following terms, "maintained", "non-maintained" and "sustained". It gives:

Non-maintained = Only illuminate under power fail conditions.

Maintained = Illuminated at all times, using same lamps for normal and emergency modes.

Sustained = Basically two set(s) of lamps, one on mains the other on battery. Similar to Non-maintained but the mains lamps should be on when ever the premises are occupied.

By implication "sustained" can be user switched (last person out turns off the lights), but the other two are not. Comments?

Reply to
Dave Liquorice

Yes, Prezicionlampholdermitfingergepluggen, the ultimate fingerpluggen machine.

Seriously, youre discussing theory here when its results that matter. I've entirely fogrotten the source, but I believe the number of deaths by electrocution from the lighting circuit currently stands at 0 per year in UK. Unexpected loss of lights while going down stairs, standing on a ladder, using a power tool, and while trying to get out in a fire account for a lot more accidents and deaths than 0.

RCBOs are better of course, but they cost more.

Regards, NT

Reply to
N. Thornton

How about a job lot of LED keyring torches off Ebay?

Do you live in a rural area with regular power cuts? If so it might be worth having a standby generator with a transfer switch.

cheers, Pete.

Reply to
Pete C

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