Probably, on the basis that there's no real need for the change so far
as they are concerned and it costs them money to send a man round... I
can't see any real justification for you to change from what sounds like
a TN-S system (earth return via sheath) to a TN-C-S system (PME - earth
return via neutral) - you'll still need the earth rod for operation from
the generator in either case.
Ok, but the reason for the change, was the earth cable from the incomer to
the CU is small (looks about 5mm) - maybe this is adequate? (The
reconnection bloke thought it was small, and suggested a PME connection)
: Will it be ok to have the earth connected to both the neutral (Mains)
and a
: rod (Generator) at the same time?
Probably yes, but again, this is something which I would confirm (in
witing!) with your electricity supplier. Sketch out the proposed circuit
arrangement (specifying cable sizes, etc.) and give them a bullet pointed
list of the main features. Remember that it is not impossible (but
fortunately quite difficult!) for you to electrocute the electricity
supplier's staff if you get this wrong so make sure they are happy. They
may not be willing to comment on your proposal but at the least should
specify what standard you should meet - probably either an electricity
supply industry standard or the appropriate parts of the IEE regs (or
both).
Okay, but with the transfer switch, there shouldn't be a problem!
Don't forget that the supply from the generator will need to be protected
by a 100mA time delayed RCD unless you have something a lot more
impressive than the average earth rod (standard earthing rules for a TT
supply). It may also be necessary anyway due to high fault current loop
impedance as a result of the generator impedance (almost certainly will
be required for a little 800VA thingy). Hopefully it is obvious to you
that the connection between neutral and earth for the generator supply
should be on the generator (supply) side of the RCD.
At the moment, it goes like this...
Main supply 80A
Generator 26A (Briggs & Stratton 7500LE) (
http://tinyurl.com/xikn)
Earth from incomer (supply sheath) to CU via 5mm cable
L&N from meter into DP isolator
L&N from isolator to transfer switch (Double Pole, Three position switch
(Mains, off & Generator))
L,N&E from generator into transfer switch (Transfer switch has a 30mA RCD
for the generator)
(The generator neutral and earth are connected together in here, before the
RCD)
The earth rod is situated next to the generator, and is connected to the
chassis of the generator (via the supplied earthing bolt)
There is also a power conditioner in between the generator and the transfer
switch (Bloody heavy!)
L,N&E then run from the transfer switch into CU (L&N into the top of the
100A/30mA RCD, and earth the opposite end of the earthing strip) - there
are then two additional L&N wires running from the top of the 100A/30mA RCD
to the 40A/30mA RCD
The generator has a 30A thermal fuse on it's control panel
Do I actually need the RCD in the transfer switch (on the generator circuit)
as all circuits are protected via the RCD's in the CU? Will this cause
problems having RCD's connected to RCD's? (I was thinking of swapping the
RCD in the transfer switch for an isolator)
Many thanks for your help!
Sparks...