[chbot] OT: Low profile RCB

Charles Manning cdhmanning at gmail.com
Tue Jul 15 00:01:26 BST 2014


Volker

Sorry if you thought the questions I posed were trolling you or
anything like that. I was genuinely interested in why you would think
a single RCD is a defective design.

I do understand that killing all the electricity when just one
appliance is faulty is overkill, but in reality RCD faults should
hardly ever - perhaps never - be triggered so the difference between a
good design and overkill is small. You're far more likely to need to
keep a flashlight/torch on hand for the normal power loss events that
hit us a few times a year.

Still it is probably wrong to dismiss as "stupid" a single RCD design
that is used successfully in tens of millions of houses in South
Africa over the last 50 years.

I never saw a radiant heater or a water heater trip an RCD in South
Africa, but then I never tried using a 6kW heater. I was envisaging an
appliance style heater (~2kW maybe).

Some years back I was talking to an NZ electrician and he said they
didn't wire laundries through RCDs because there's so often leakage in
wet areas. That stunned me. Surely if there is chance of leakage, that
is exactly where you want an RCD!




On Tue, Jul 15, 2014 at 10:03 AM, Volker Kuhlmann
<list0570 at paradise.net.nz> wrote:
> On Tue 15 Jul 2014 08:54:24 NZST +1200, Marshland Engineering wrote:
>
>> 30 ma is 30 ma regardless of how many breakers you have. We have one 3 phase RCD of 30 ma one feeding about 40 CB. We have a 'big' house many flouresecnt tubes, 1 fridge, 3 freezers, 1 large mill, 2 large lathes, 3 hot water cylinders, 2 heat pumps, dozens of computers, one 4 kw oil heater, washing machine, tumble drier, and still, I've
>> never had to find and reset the RCD in the dark (or even the light for that
>> matter).
>
> And all those loads were connected downstream of theRCD? Are you sure?
>
>> >Seems to work in South Africa when I lived there, but maybe the laws
>> >of physics were different under apartheid.
>>
>> Oh yes. Made me laugh.
>
> Keep laughing, I don't care. You two smartalecs are welcome to come over
> and do your own measurements on the 6kW heater I have here. Your
> suggestion of replacing a brand-new heater here in New Zealand just
> because it doesn't fit your South African wiring made *me* laugh...
>
> Volker
>
> --
> Volker Kuhlmann
> http://volker.top.geek.nz/      Please do not CC list postings to me.
>
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