Two recent threads about moving a CU mentioned that an additional 100
Amp DP isolator was fitted after the meter. When is this necessary?

As my installation doesn't have one I will need to break the seal and
pull the cutout when I eventually swap my CU for a 17th edition one.

Meter is in cupboard outside, and about two meters of tails though the
porch wall to the CU.
Supply is TN-S (I think).

--
Graham.
%Profound_observation%

Graham. wrote:


Two recent threads about moving a CU mentioned that an additional 100
Amp DP isolator was fitted after the meter. When is this necessary?

It's not - it's a convenience to save pulling the cutout fuse.

As my installation doesn't have one I will need to break the seal and
pull the cutout when I eventually swap my CU for a 17th edition one.

You could install your own at that time - it's nothing more than a 100A DP
main switch (from a CU) fitted in a nice Wylex slimline housing with 4 entry
holes optimised for meter tails.


Meter is in cupboard outside, and about two meters of tails though the
porch wall to the CU.
Supply is TN-S (I think).

--
Tim Watts Personal Blog: http://www.dionic.net/tim/

"History will be kind to me for I intend to write it."

Owain wrote:
On Nov 27, 9:25 pm, Graham. wrote:
Meter is in cupboard outside, and about two meters of tails though
the porch wall to the CU.

Depends on the DNO, but if the tails are more than 3m some insist on a
switch-fuse to provide overcurrent protection to the tails.

Isoaltor only:
http://www.tlc-direct.co.uk/Products/WYREC2S.html

I am not sure I get this bit of the link

"It's safer because the supply tails are fixed and finalised in a sealed
unit - instead of being left hanging loose ready to connect to the meter."

--
Adam

ARW wrote:
I am not sure I get this bit of the link
"It's safer because the supply tails are fixed and finalised in a sealed
unit - instead of being left hanging loose ready to connect to the meter."

I was puzzled by that. From what they did in my place I inferred it
mean that the consumption-side installer installs consumption-side
tails into the isolator, and the the supplier comes along and installs
the supply-side tails into the isolator; instead of installing the CU
and leaving a pair of tails dangling for the supplier to wire into
their meter.

JGH

In article
s.com, Owain scribeth thus
On Nov 28, 10:18*pm, jgharston wrote:
ARW wrote:
I am not sure I get this bit of the link
"It's safer because the supply tails are fixed and finalised in a sealed
unit - instead of being left hanging loose ready to connect to the meter."

ITYM 'left hanging loose ready to connect to the CU"

I was puzzled by that. From what they did in my place I inferred it
mean that the consumption-side installer installs consumption-side
tails into the isolator, and the the supplier comes along and installs
the supply-side tails into the isolator; instead of installing the CU
and leaving a pair of tails dangling for the supplier to wire into
their meter.

If the supply-side tails are installed first they can be installed
into the supply side of the isolator and the isolator locked off. Then
there are no live parts. The customer-side tails go into the dead
customer-side of the isolator and the isolator is only unlocked when
everything's nice and safe.

No pulling the Big Fuse, no risk of arcing, etc.

In some fit-outs the supply and meter will go in before the CU and
internal wiring so there are no customer tails to connect at that
time.

Owain




JOOI what spec does the cut out isolator switch have to be?.

Would a 100 amp one in a wall mounted 2 Units wide DIN rail enclosure
be sufficient?...


Like these?..

http://www.toolstation.com/shop/Elec...umer+Units/Sch
neider+Switch+Disconnector+100A+DP/d190/sd2901/p90524

http://www.toolstation.com/shop/Elec...nits/Enclosure
+IP20+2+Module/d190/sd2979/p30350



--
Tony Sayer

tony sayer wrote:

JOOI what spec does the cut out isolator switch have to be?.

Would a 100 amp one in a wall mounted 2 Units wide DIN rail enclosure
be sufficient?...


Like these?..

http://www.toolstation.com/shop/Elec...umer+Units/Sch
neider+Switch+Disconnector+100A+DP/d190/sd2901/p90524

http://www.toolstation.com/shop/Elec...nits/Enclosure
+IP20+2+Module/d190/sd2979/p30350

An isolator is just a DP main switch in a suitable housing - yes the above
would work.

The Wylex REC2S is a bog standard main switch in a highly optimised housing.

http://www.fastlec.co.uk/wylex-100a-...losure-supply-
isolator-
p-14050.html?utm_source=googlebase&utm_medium=feedma nager&utm_term=cx_term&utm_content=cx_content&utm_ campaign=cx_name#.ULdipOC6mtY

The one thing about the REC2S is you can remove the cover on the load side
terminals only, leaving the supply side covered. This makes it a tiny bit
safer.


--
Tim Watts Personal Blog: http://www.dionic.net/tim/

"She got her looks from her father. He's a plastic surgeon."