i have often wondered what the cost is of running an rcbo.
Always notice wamth just detectable......
new boy on the site

That`s sad!
So am I though.
LOL.
I often wondered how much of the heating effect of suppliers supply meter we were paying for either by losing a bit of voltage from the current coil or current from the voltage coil.

Our circuit designs should allow use to keep circuit runs to minimum length to cut down on volt drop per amp per length dissapation.
Mind you all cables run inside help to warm the building up so we keep clear of external cables.

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Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik

Its usually the capital cost of these little characters that appear to generate the heat particularly when the invoice arrives.
Other causes of excessive heat are sometimes due to loose terminal connections at the bus bar or/and final circuit terminations.
Otherwise a nice warm box for the winter will keep the condensation at bay....

Legh

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Why do we need Vernier Calipers when we have container ships?

http://www.leghrichardson.co.uk

"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."

On of my customers is becoming a expert on bed bugs, apparently they get into back boxes behind light switches and sockets because they like the warmth within the box. So it is necessary for a electrician to dismantle the accessory so the cleaning operative can dry sanitise the back of the accessory and its back box.

Andy

I would estimate the power used by an unloaded RCBO at about one watt, from the heat produced.
So that is about 8 or 9 KWH a year or between £1 and £2 a year.

So what's the standing losses on a typical house?

Andy

The loss on a 400kv line are something like 6000 volts, thats the sort of loss you should be worrying about not a tiny bit on an rcbo or a meter!

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Lack of planning on your part doesn't make it an emergency on mine....

Every man has to know his limitations- Dirty Harry

I think it's a good question. As RCBOs are getting more popular and we see more 'all-RCBO' CUs, there will be quite a number across the country. If each house were to have an average of say 4 RCBOs, with something like 20 million homes, that's 80 million RCBOs, It all adds up.

I did try hooking a couple of spare RCBOs into a supply from a cheap plug-in power meter (not exactly scientific as it'll be well outside its intended parameters, although the power meter can tell the difference between 'standby' and 'off' with most appliances) - and it didn't register anything - so I'm suspecting it's a bit below 1W (at least for the DP models I tried).

- Andy.

What you want is the datasheet for a particular RCBO and get the off-load coil impedance, work that using the formulae V²/Z giving you the power consumption. Im guessing <100mW off the top of my head and what the hell am i doing writing this sort of stuff at this time in the morning i should be on the JD

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From SMD's to 132kV... ive had a go!

Richard Talmage, LCGI EngTech TMIET

This seems to be deemed a RCBO issue where is additional impedance really coming from compared to a MCB?

Andy

Specifically, Z = R here.

Regards

I posed the question "This seems to be deemed a RCBO issue where is additional impedance really coming from compared to a MCB?", take for example a MEM MCB onto which you clip a RCD Pod http://edmundson-electrical.vo...details&catalogType=P

Where is most of the impedance? Presumably all of the resistance is in the MCB?

Andy

My assumption (as ever perhaps wrong) was that most RCBOs have amplifier electronics permanently in circuit between L&N - thus are consuming a small amount of power 24x7 even when there's no load drawing current.

- Andy.

more replies than i expected.

at the last visit the nic man agreed that rcbos are an active device therefore have a consumption value - however small.

have only ever used rcbos (YES REALLY) therefore a 20 module consumer unit must have a significant running cost.....

I have just taken a reading of 6.1 mA from a chint B16A RCBO, switched on with no load connected, voltage 244V

0.0061 X 244 = 1.4884 W

1.5W = 0.0015 KW/h

At 10p per KW/h = 0.0015p/h

8760 hours per year X 0.0015 = £13.14

So a board with 10 rcbo's on standby might cost £130 a year in electric??


I'd be happy to be corrected if my sums are wrong!

6.1mA on the Ph line in with no output connected?

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Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik

Yes.

What about the power factor? remember this thread: http://www.theiet.org/forums/f...tid=205&threadid=45504 ?

- Andy.

Hi all, sorry, but please disregard my earlier post - tried it again today and got only 0.017mA, not sure if it was meter or user error, probably both