"Andy Wade" wrote in message
...
Stefek Zaba wrote:

But I've neither read deeply nor thought hard about this, so I'd welcome
anyone better-informed weighing in...

I haven't been following this thread that closely, but the recent
questions seem to be ...

Yea, but, when I earth my metal gas pipe and metal water pipe, like the
good little boy I am, does this then make my house installation partly
TT, thus potentally unsafe as you describe!
(This is why I asked :-) )

An installation can't be partly TT. If there's a metallic earth path back
to the substation transformer then it's TN, if there isn't then it's TT.
(IT doesn't apply here.)

Can any one shed any light on this question!?

(Another reason I ask this, is, if a generator is installed, this has to
have a rod (AIUI), but if this has a rod, connected to the house earth
supply, does this them break the earthing rules on my TN-S system?)

Transfer switches only seem to switch the L&N (Via an "all off" position)

A generator installation has to have its own means of earthing, in case
the connection to the supply distributor's mains earth has been severed.
The earths can be connected in parallel - there's no need for switching.


Okay, the origanal question was why shouldt I connect the house earth to the
garage TT earthing arangement - why must they be kept seperate?
(The cable run up to the garage is about 50m in 4mm SWA)


NB 2. Reg. 551-02-03 requires automatic load shedding arrangements if the
generator is not rated to supply the whole installation.


So it has to be impossible to switch on too much?
or can there just be some instructions to turn off some MCB's?


Sparks...