Has anyone a 4 pole (ie 3 phase with switched neutral) isolator /
switch disconnector / switch fuse with a rating of 160a - 200a or
greater kicking arround that they'd like to convert to folding money?
I'm having a somewhat larger than normal 3 phase supply installed and
would like it's first point of calling to be an isolator - being 'TT'
it needs to be four pole.

AWEM

On Tue, 22 Jul 2008 08:39:45 +0100, "Andrew Mawson"
 wrote:

>Has anyone a 4 pole (ie 3 phase with switched neutral) isolator /
>switch disconnector / switch fuse with a rating of 160a - 200a or
>greater kicking arround that they'd like to convert to folding money?
>I'm having a somewhat larger than normal 3 phase supply installed and
>would like it's first point of calling to be an isolator - being 'TT'
>it needs to be four pole.
>
>AWEM

What is 'TT' ?? and why do you need to break the Neutral, which should be tied
to ground anyway?

Peter
--
Peter A Forbes
Prepair Ltd, Rushden, UK
peterforbes@prepair.co.uk
http://www.prepair.co.uk
http://www.prepair.eu

"Peter A Forbes"  wrote in message
news:cm6b84tktpl54rl5a9kpp24tptdhl4dcqk@4ax.com...
> On Tue, 22 Jul 2008 08:39:45 +0100, "Andrew Mawson"
>  wrote:
>
> >Has anyone a 4 pole (ie 3 phase with switched neutral) isolator /
> >switch disconnector / switch fuse with a rating of 160a - 200a or
> >greater kicking arround that they'd like to convert to folding
money?
> >I'm having a somewhat larger than normal 3 phase supply installed
and
> >would like it's first point of calling to be an isolator - being
'TT'
> >it needs to be four pole.
> >
> >AWEM
>
> What is 'TT' ?? and why do you need to break the Neutral, which
should be tied
> to ground anyway?
>
> Peter
> --
> Peter A Forbes
> Prepair Ltd, Rushden, UK
> peterforbes@prepair.co.uk
> http://www.prepair.co.uk
> http://www.prepair.eu

Overhead supply - ground is by earth electrode, EDF do not guarantee
neutral will stay near earth despite the fact I can see the main bond
between neutral and earth on the transformer on my land 20 yds from
where the supply will terminate ! With TT supplies Neutral has to be
treated like a live conductor.

See:

http://tinyurl.com/68qqpf


AWEM

> What is 'TT' ?? and why do you need to break the Neutral, which should be tied
> to ground anyway?
>
> Peter
> --
> Peter A Forbes
> Prepair Ltd, Rushden, UK
> peterfor...@prepair.co.ukhttp://www.prepair.co.ukhttp://www.prepair.eu

TT is a supply where the supplier does not provide an earth.Earthing
on the customer premises is by ground rod.Neutral must never be tied
to earth in these circumstances.
I did not know there was a requirement to switch the neutral and would
be very surprised if the board is asking for that,but wait to be
corrected.
I think there is also a requirement for an RCD on the incomer.
TT is quite common in rural situations.
Mark.

Mark.

wrote in message
news:bd47f335-0b1d-445c-942a-ce8eca6b6909@s50g2000hsb.googlegroups.com...
>
>
> > What is 'TT' ?? and why do you need to break the Neutral, which
should be tied
> > to ground anyway?
> >
> > Peter
> > --
> > Peter A Forbes
> > Prepair Ltd, Rushden, UK
> >
peterfor...@prepair.co.ukhttp://www.prepair.co.ukhttp://www.prepair.eu
>
> TT is a supply where the supplier does not provide an earth.Earthing
> on the customer premises is by ground rod.Neutral must never be tied
> to earth in these circumstances.
> I did not know there was a requirement to switch the neutral and
would
> be very surprised if the board is asking for that,but wait to be
> corrected.
> I think there is also a requirement for an RCD on the incomer.
> TT is quite common in rural situations.
> Mark.
>
> Mark.
>

Correct - there is no EDF requirement to switch any of  the incoming
cables, but for testing purposes on a TT system Neutral has to be
treated as a potentially live conductor so must be isolated. Also
correct that an RCD is required -  100mA trip on the whole system, and
the 30mA type on all sockets.

AWEM

ps anyone got an isolator???????

>
> > TT is a supply where the supplier does not provide an earth.Earthing
> > on the customer premises is by ground rod.Neutral must never be tied
> > to earth in these circumstances.
> > I did not know there was a requirement to switch the neutral and
> would
> > be very surprised if the board is asking for that,but wait to be
> > corrected.
> > I think there is also a requirement for an RCD on the incomer.
> > TT is quite common in rural situations.
> > Mark.
>
> > Mark.
>
> Correct - there is no EDF requirement to switch any of  the incoming
> cables, but for testing purposes on a TT system Neutral has to be
> treated as a potentially live conductor so must be isolated. Also
> correct that an RCD is required -  100mA trip on the whole system, and
> the 30mA type on all sockets.
>
> AWEM
>
> ps anyone got an isolator???????

Andrew,all three phase isolators have a detachable link on the neutral
terminal block for testing purposes.
Mark.

You`ve probably seen this.I`ve bought from this guy and he`s sound.
http://cgi.ebay.co.uk/BILL-200-AMPS-SWITCH-FUSE-TPN_W0QQitemZ350076873609QQcmdZViewItem?hash=item350076873609&_trksid=p3286.m14.l1318

On Tue, 22 Jul 2008 08:39:45 +0100, "Andrew Mawson"
 wrote:

>Has anyone a 4 pole (ie 3 phase with switched neutral) isolator /
>switch disconnector / switch fuse with a rating of 160a - 200a or
>greater kicking arround that they'd like to convert to folding money?
>I'm having a somewhat larger than normal 3 phase supply installed and
>would like it's first point of calling to be an isolator - being 'TT'
>it needs to be four pole.
>
>AWEM


Haven't got one you can have, but if you can put up with new then you can use
one of these:-

http://www.tlc-direct.co.uk/Main_Index/Distribution_and_Switchgear_Index/CMD_Switch_Main/CMD_Switch160/index.html

Never had any problems with these folk.

The other thing to do is to just ask the frogs to fit an isolator when they
install the supply. Worked for me when I got my meter changed (not by edf and
not three phase though...)



Mark Rand
RTFM

In article
,  
 "mark@ems-fife.co.uk"   in
uk.rec.models.engineering wrote:

>
>>
>> > TT is a supply where the supplier does not provide an earth.Earthing
>> > on the customer premises is by ground rod.Neutral must never be tied
>> > to earth in these circumstances.
>> > I did not know there was a requirement to switch the neutral and
>> would
>> > be very surprised if the board is asking for that,but wait to be
>> > corrected.
>> > I think there is also a requirement for an RCD on the incomer.
>> > TT is quite common in rural situations.
>> > Mark.
>>
>> > Mark.
>>
>> Correct - there is no EDF requirement to switch any of  the incoming
>> cables, but for testing purposes on a TT system Neutral has to be
>> treated as a potentially live conductor so must be isolated. Also
>> correct that an RCD is required -  100mA trip on the whole system, and
>> the 30mA type on all sockets.
>>
>> AWEM
>>
>> ps anyone got an isolator???????
>
>Andrew,all three phase isolators have a detachable link on the neutral
>terminal block for testing purposes.

There is a requirement in the wiring regs requiring that all circuit
conductors can be disconnected from the supply by a "linked switch".
ie phase(s) and neutral, but there's an easement such that if one
conductor is effectively earthed, the you need only switch the live
conductor(s) and provide a bolted neutral isolating link.  Dunno where
it is in the madness that passes for the regs these days, but it's A2
in the 14th edition.

Regards,

David P.