[chbot] OT: Low profile RCB

[Charles Manning]

We've bashed this one to death.... but...

I generally agree that devices should be designed with near as
possible zero leakage. However, many devices that are zero leakage
when off can still leak at  high voltage.

>From the perspective of physics, a radiant heater is really no
different than the heater in a valve (vacuum toob for Americans). If
the heater element is close enough to the ground to create a
sufficient e field then electrons will be excited and will flow
through the air to to ground. ie. Leakage.

The difference though is that valve heaters (and the whole valve) are
designed to leak and radiant heaters should not be. Even with a high
kW heater I would expect it should be possible to design the unit to
keep well below 30mA (eg. keeping a reasonable space between the
earthing and the element, selection of insulation materials,...). But
that's just a hunch... I have not done the numbers.

Part of the problem probably comes from trying to retro-fit regs to
existing households and installations. There is always compromise to
allow someone to keep their 15 year old washing machines and other
appliances that leak - both water and electricity.



On Tue, Jul 15, 2014 at 12:16 PM, Marshland Engineering
<marshland at marshland.co.nz> wrote:
> If the powers that be, recommend 30 mA as safe limit for an RCD then any
> applinace that has more than that should be returned.  No question about
> that. If you cant desgin something to have basiscially zero leakge, go back
> to the drawing board and start again.
>
>
>
> Another interesting point is that there are no 240 switches or socket
> outlets in any bathroom, shower or toilet (wet areas) in SA and this is with
> RCD installed in the DB. All switches are on the outside of the room.
>
>
>
> Cheers Wallace.
>
>
>
>
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