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circuit-breaker allegedly "getting more sensitive"

Former Community Member over 4 years ago

OK, usual caravan park issues with more pitches than incoming supply, so client has acknowledged this by installing 10 A circuit-breakers for each 16 A outlet. With 24 pitches on a presumed 80 A single-phase cut-out, he has got away with it..... so far, but he doesn't close for winter....

He has a few regulars that complain about the 10 A circuit-breaker being too sensitive so client believes them and has fitted new 10 A circuit-breakers ready for this weekend.

Considering that a 10 A circuit-breaker will run at 11.3 A continuously and 16 A for about 10 minutes, I'm more inclined to think that the "shed puller's" use of the 2 kW built in heater, 2 kW supplementary fan heater, fridge and domestic 3 kW kettle plus entertainment equipment are more likely....

But, has anyone carried out any tests on circuit-breakers to prove/disprove the alleged reduced rating? Or links to any such reports?

Regards

BOD

0 mapj1 over 4 years ago

perspicacious:
....we recommend a 60% diversity factor is applied to the MCB nominal rated current where it is

intended to load the MCB' s continuously (in excess of 1 hour).

...

Hmm, so a EICR carried out on my dwelling with a 16 A circuit-breaker on my 3 kW immersion heater in a 210 litre cylinder would result in what code? ...

Well reading the rest of the advice, it only applies to close packed breakers, so no code if the breakers on either side were lightly loaded, or its suggests you should fit a 20A one if they are.

Perhaps they think we should fit 40A breakers to 32A rings to avoid stressing the breakers. I'd disagree.

I suggest that like the total demand diversity calculations themselves, where we see breakers totally 200-300A on a 100A company fuse with no issues , this is so much cobblers.

regards

Mike.
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0 Sparkingchip over 4 years ago

63 or 80 amp RCD in a split load consumer unit with a 100 amp service fuse as the upfront protection?

What does the Wiring Regulations have to say about it?
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0 Sparkingchip over 4 years ago

A picture speaks a thousand words.
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0 Chris Pearson over 4 years ago

perspicacious:

Hmm, so a EICR carried out on my dwelling with a 16 A circuit-breaker on my 3 kW immersion heater in a 210 litre cylinder would result in what code? Assuming naturally that the rest of my dwelling electrics are perfect.................................

Just how big is your bath BOD?

Assume incoming water temperature is 10 deg C and you want 80 litres at 40 deg C.

It takes 1 calorie = 4.2 J to heat 1 cc of water by 1 deg C

4.2 x 30 = 126 J to heat 1 cc by 30 deg C

= 126 W for 1 sec

80 l = 80,000 cc so we need 126 x 80,000 W for 1 sec

a 3 kW immersion will take 126 x 80,000 ÷ 3,000 sec

= 126 x 80 ÷ 3 = 3360 sec or 56 minutes.
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0 Sparkingchip over 4 years ago

I have been paid to stand with a stop watch and a thermometer to find out how long it takes to fill a walk-in bath with water at 38 degrees and to what depth it can be filled.

I can assure you you need a big cylinder with the water in it pushing 60 degrees, so the thermostatic mixer can blend it down with cold water. Most cylinders will fill a walk-in to about an inch and a half above the seat, which is not enough.
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0 Former Community Member over 4 years ago

Just how big is your bath BOD?

Reminds me Chris of the time when I called in to see married couple whose wife was about 9 and a half months pregnant and just got out of the bath and she calls out to hubby: "Do you want me to leave the water in?" and his reply was: "What water?".

Likewise, whilst I have a standard size bath, I don't need much water to bathe in!

Perhaps I should have used the example of 6 NS heaters on 16 A circuit-breakers all in a row for the "derating" scenario?

Regards

BOD
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0 Former Community Member over 4 years ago
This is what we call

"The importance of education as well as technical understanding and also competent in the wiring".

Not such the assuming testing required but need the standard methods and using related testing to find the cause or problems.
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0 Sparkingchip over 4 years ago

Protective Devices

Each socket-outlet must be protected individually against overcurrent by a miniature circuit- breaker (MCB) complying with BS EN 60898. The normal current rating for each MCB is 16A, as on Club sites; to reduce the cost of the installation, it is possible to limit the current available at each socket-outlet by fitting an MCB of 10A or 6A rating, in which case the available current must be clearly indicated to members, for example by a permanent and legible notice. If less than a 16A supply is to be made available, the Member should be informed at the time of booking.

The Caravan Club

I had left that page open on my Ipad for the last week without getting around to commenting on it.

It seems quite likely that a MCB that trips regularly due to overloading will start to trip more easily as the mechanism inside it frees up.

Andy Betteridge
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circuit-breaker allegedly "getting more sensitive"

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