[chbot] OT: Low profile RCB

[Robin Gilks]

> On Sun 13 Jul 2014 23:11:03 NZST +1200, Marshland Engineering wrote:
>
>> Coming from South Africa - every (we legal) house had an RCD in line
>> the incoming mains. Ie every circuit was protected. I've did this in
>> our house we built 14 years ago an never had a problem. Would do the
>> same again.
>
> Not legal in New Zealand. It's also a really bad idea to have a single
> RCD for your whole house! The limit here may be 3 breakers per RCD now.
> I bet it's partially to stop unscrupulous tradespeople from increasing
> profits by creating substandard installations (a single RCD for a house
> is substandard as far as I am concerned, no matter the law).
>
>> If fridges and freezers start to trip it - get rid of them and get
>> new.
>
> Yes. Because in a house meeting current requirements they must have an
> RCD and therefore would no longer work.
>
> But that system fails with heaters, because heating elements have a
> natural earth leakage when hot. I last noticed this when I tried to get
> a heater an RCD, but each of the 1.5kW elements alone would trip the
> 30mA RCD within 45s when cold. All elements were out of the box and
> unused. That's why large heaters with fixed installation (kitchen
> stoves, hot water elements, etc) don't need an RCD. It wouldn't work
> anyway. All of these appliances must still be earthed, shouldn't be
> opened and have fixed wiring, so an RCD would give little extra
> protection anyway.

Something wrong with your RCD - maybe its an older style earth leakage
sensor type. All they *SHOULD* do is compare live and neutral current and
if they differ by more than the amount specified on the front then trip.

My system has a 200mA trip on each of the 3 phases immediately after the
main isolation switch. Each phase has something like 10 breakers on it.
Sub -boards have their own RCDs.

Cheers

-- 
Robin Gilks