On Thu, 21 Apr 2005 23:38:23 +0100, "Sparks" wrote:

Just checking it's not just me, but I think my new induction hob is faulty!!

Probably not.

When turning on the local isolator near the hob, the RCD trips.
If I reset the RCD it will trip either immediately or after a few seconds
If I isolate the hob (Via the double pole isolator, OR by the single pole
MCB in the CU) the tripping stops.

Induction hobs use high frequency and high current in the induction
coils. The switching electronics produce a lot of RF interference
which needs to be filtered to stop it getting back into the mains
supply.

A whole house RCD isn't fussed about where leakage is coming from and
if you have a number of noise filtered devices (such as computers,
printers, fax machines)on other circuits then each can leak about
3.5mA and it is likely that the RCD is already on the point of
tripping and the hob filter has just pushed it over the edge. Noise
filter leakage usually occurs whether the device is switched on
(using its own power switch) or not.

If I measure the current between its earth wire and Neutral, I am getting
about 2.9A

The current reading is irrelevant as has been pointed out.

If I measure the voltage, it is about 120v

Which is exactly as you would expect from a noise filtered device.

Do I send it back, or connect it to the non RCD CU!
(I personally would think 120v @ 2.9A leakage to earth is not too clever,

It isn't there. Your measurement ignored the neutral/earth voltage
difference. You would get similar results from any device in the
house.

would think it is faulty, but would just like to see what others think)

Connecting lots of things to a single 30mA RCD is a recipe for
nuisance tripping. You seem to have somewhat of an attachment to
RCD's so if you really want one connect the hob to a non-RCD circuit
and put a dedicated RCD on the hob alone.

Is not RCD protecting things like this really as wise as people make out?

Yes - whole house RCD's have killed more people than they have saved.
Increasing use of electronic devices and the increased need for RF
filtering means many houses now qualify as high protective conductor
current environments and should meet Sect 607 requirement.
(www.cda.org.uk/megab2/elecapps/pub142lo.pdf covers Sect 607 well).

Sparks (who wants to RCD everything possible, now more than ever!)

If you feel you must then use lots of individual RCD's at each device
you wish to protect.

--
Peter Parry.
http://www.wpp.ltd.uk/