Hi, I'm planning to cut into the ground floor power cable ring and
extend it into the adjacent, integral garage. The concrete block walls
of the garage will make it necessary to run the cable in conduit
(plastic).

I intend to have one vertical run of 2.5M, with 3 x 2 gang boxes and
sockets contained within this run. I then want to elbow the top and
place another 2 gang box and socket at the end of a 1.5M horizontal
run, which will then form an inverted L shape. To maintain the ring
structure I'll need to return the cable to the extension starting
point.

Is it common practice to return the cable down the same conduit that
it came up in, or is it better to form a conduit loop?
The latter option is going to require twice as much conduit, so I'd
rather use the former method if practical.

--
Kind regards,
Geoff Mills

On Wed, 16 Sep 2009 16:09:50 +0100 someone who may be Geoff Mills
wrote this:-

Is it common practice to return the cable down the same conduit that
it came up in,

Yes.

Assuming metal conduit, if there is not a copper protective
conductor drawn into the conduit then you need to be particularly
careful about making proper joints to maintain the continuity of the
trunking which forms the protective conductor.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

In an earlier contribution to this discussion,
David Hansen wrote:

On Wed, 16 Sep 2009 16:09:50 +0100 someone who may be Geoff Mills
wrote this:-

Is it common practice to return the cable down the same conduit that
it came up in,

Yes.

Assuming metal conduit, if there is not a copper protective
conductor drawn into the conduit then you need to be particularly
careful about making proper joints to maintain the continuity of the
trunking which forms the protective conductor.


He explicitly said he'd be using plastic conduit!
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

On Wed, 16 Sep 2009 16:44:53 +0100 someone who may be "Roger Mills"
wrote this:-

He explicitly said he'd be using plastic conduit!

Apologies. I didn't spot the orphaned word.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On Wed, 16 Sep 2009 16:29:27 +0100, David Hansen
wrote:

On Wed, 16 Sep 2009 16:09:50 +0100 someone who may be Geoff Mills
wrote this:-

Is it common practice to return the cable down the same conduit that
it came up in,

Yes.

Assuming metal conduit, if there is not a copper protective
conductor drawn into the conduit then you need to be particularly
careful about making proper joints to maintain the continuity of the
trunking which forms the protective conductor.

Thanks,
I hadn't considered metal conduit before, nor that the conduit itself
could be used for earthing. Lots to learn.
--
Kind regards,
Geoff Mills

In article ,
Geoff Mills wrote:
I hadn't considered metal conduit before, nor that the conduit itself
could be used for earthing. Lots to learn.

Much stronger if in the sort of place where it could get bashed.
The minimum you'd need is a die to thread the cut ends. Assuming you can
do it all in straight runs.

--
*Nothing is foolproof to a sufficiently talented fool*

Dave Plowman London SW
To e-mail, change noise into sound.

On Thu, 17 Sep 2009 09:37:59 +0100, "Dave Plowman (News)"
wrote:

In article ,
Geoff Mills wrote:
I hadn't considered metal conduit before, nor that the conduit itself
could be used for earthing. Lots to learn.

Much stronger if in the sort of place where it could get bashed.
The minimum you'd need is a die to thread the cut ends. Assuming you can
do it all in straight runs.

Good points. I'm usually a belt and braces man but the relative ease
of working with plastic conduit is going to swing it on this occasion.
--
Kind regards,
Geoff Mills

"Geoff Mills" wrote in message
...
On Wed, 16 Sep 2009 16:29:27 +0100, David Hansen
wrote:

On Wed, 16 Sep 2009 16:09:50 +0100 someone who may be Geoff Mills
wrote this:-

Is it common practice to return the cable down the same conduit that
it came up in,

Yes.

Assuming metal conduit, if there is not a copper protective
conductor drawn into the conduit then you need to be particularly
careful about making proper joints to maintain the continuity of the
trunking which forms the protective conductor.

Thanks,
I hadn't considered metal conduit before, nor that the conduit itself
could be used for earthing. Lots to learn.

Metal conduit is excellent if you need more mechanical protection than heavy
duty plastic offers, but it is not easy to work with. You need a pipe
threader and, if you want to make pretty shapes, which you can do with care
and a hot air gun in PVC, a pipe bender. As noted, the earthing it offers
can be unreliable, so I always run earth wires in it as well.

Colin Bignell

On Thu, 17 Sep 2009 08:40:14 +0100 someone who may be "nightjar"
cpb@insert my surname here.me.uk wrote this:-

As noted, the earthing it offers
can be unreliable, so I always run earth wires in it as well.

If it is installed and maintained improperly. However, that is true
of other ways of doing the same thing.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

"David Hansen" wrote in message
...
On Thu, 17 Sep 2009 08:40:14 +0100 someone who may be "nightjar"
cpb@insert my surname here.me.uk wrote this:-

As noted, the earthing it offers
can be unreliable, so I always run earth wires in it as well.

If it is installed and maintained improperly. However, that is true
of other ways of doing the same thing.

For the marginal cost of an extra wire run, it is safer to assume that it
will, at some point, not be properly maintained.

Colin Bignell

"Geoff Mills" wrote in message
...
Hi, I'm planning to cut into the ground floor power cable ring and
extend it into the adjacent, integral garage. ...

Is it common practice to return the cable down the same conduit that
it came up in, ...

It is acceptable, but if you are using twin and earth cable, rather than
individual conduit wires, you may find it a bit of a tight fit around elbows
in 20mm conduit. I prefer 25mm conduit if I am running two 2.5mm T&E cables.

Colin Bignell

On Wed, 16 Sep 2009 18:01:10 +0100, "nightjar" cpb@insert my surname
here.me.uk wrote:


"Geoff Mills" wrote in message
.. .
Hi, I'm planning to cut into the ground floor power cable ring and
extend it into the adjacent, integral garage. ...

Is it common practice to return the cable down the same conduit that
it came up in, ...

It is acceptable, but if you are using twin and earth cable, rather than
individual conduit wires, you may find it a bit of a tight fit around elbows
in 20mm conduit. I prefer 25mm conduit if I am running two 2.5mm T&E cables.

Colin Bignell

Thanks, I started out with the idea that I'd be using T&E cable though
perhaps individual wires are more suitable. But then again, if that is
so, why would anyone be running 2 T&E cables through conduit?

--
Kind regards,
Geoff Mills

"Geoff Mills" wrote in message
...
....
Thanks, I started out with the idea that I'd be using T&E cable though
perhaps individual wires are more suitable. But then again, if that is
so, why would anyone be running 2 T&E cables through conduit?

Individual wires is the better choice. However, it probably depends upon
whether you are doing enough to justify buying three reels of conduit wire.

Colin Bignell

On Thu, 17 Sep 2009 08:28:30 +0100, "nightjar" cpb@insert my surname
here.me.uk wrote:


"Geoff Mills" wrote in message
.. .
...
Thanks, I started out with the idea that I'd be using T&E cable though
perhaps individual wires are more suitable. But then again, if that is
so, why would anyone be running 2 T&E cables through conduit?

Individual wires is the better choice. However, it probably depends upon
whether you are doing enough to justify buying three reels of conduit wire.

Colin Bignell

Are individual wires not usually sold by the metre? I like the idea of
these because only one earth wire would be needed. Trouble is the girl
who answered the phone at the local Peco said she'd never heard of
using individual wire. She always sells T&E for the purpose and this
with 20mm conduit, as 25mm is special order and only sold in bulk.
Fortunately there is a local Screwfix now.
--
Kind regards,
Geoff Mills

In article ,
Geoff Mills wrote:
Individual wires is the better choice. However, it probably depends
upon whether you are doing enough to justify buying three reels of
conduit wire.

Colin Bignell

Are individual wires not usually sold by the metre? I like the idea of
these because only one earth wire would be needed. Trouble is the girl
who answered the phone at the local Peco said she'd never heard of
using individual wire. She always sells T&E for the purpose and this
with 20mm conduit, as 25mm is special order and only sold in bulk.
Fortunately there is a local Screwfix now.

TLC cut most cables - but not this one. Probably no demand. You could
check Ebay, though.
Just for info you used to be able to get it in stranded too - which made
pulling through conduit that much easier. Dunno if you still can.

--
*It's this dirty because I washed it with your wife's knickers*

Dave Plowman London SW
To e-mail, change noise into sound.

"Geoff Mills" wrote in message
...
On Thu, 17 Sep 2009 08:28:30 +0100, "nightjar" cpb@insert my surname
here.me.uk wrote:


"Geoff Mills" wrote in message
. ..
...
Thanks, I started out with the idea that I'd be using T&E cable though
perhaps individual wires are more suitable. But then again, if that is
so, why would anyone be running 2 T&E cables through conduit?

Individual wires is the better choice. However, it probably depends upon
whether you are doing enough to justify buying three reels of conduit
wire.

Colin Bignell

Are individual wires not usually sold by the metre?

I always buy frrom my local electrical wholesaler, who would probably give
me a very odd look if I asked to buy anything other than armoureed cable in
cut lengths. I usually buy conduit wire in 100m reels. I think 50m is also
available, but I used more than one of the 100m reeels last time I did a
factory rewire, so it wasn't worth buying less.

I like the idea of
these because only one earth wire would be needed. Trouble is the girl
who answered the phone at the local Peco said she'd never heard of
using individual wire. She always sells T&E for the purpose and this
with 20mm conduit, as 25mm is special order and only sold in bulk.

Again, my local electrical wholesaler (Newey & Eyre) will supply 25mm in
single lengths. It is to order only, but delivery is next day, to my
address.

Colin Bignell

In article ,
Geoff Mills wrote:
Thanks, I started out with the idea that I'd be using T&E cable though
perhaps individual wires are more suitable. But then again, if that is
so, why would anyone be running 2 T&E cables through conduit?

Saves buying the singles? They have thicker insulation than stripped TW&E.
And IIRC only come in 100 mtr drums - dunno anyone that sells cut lengths.

--
*No hand signals. Driver on Viagra*

Dave Plowman London SW
To e-mail, change noise into sound.

On Thu, 17 Sep 2009 09:41:44 +0100, "Dave Plowman (News)"
wrote:

In article ,
Geoff Mills wrote:
Thanks, I started out with the idea that I'd be using T&E cable though
perhaps individual wires are more suitable. But then again, if that is
so, why would anyone be running 2 T&E cables through conduit?

Saves buying the singles? They have thicker insulation than stripped TW&E.
And IIRC only come in 100 mtr drums - dunno anyone that sells cut lengths.

Is stripped T&E a realistic option for a small job? If so, does the
earth wire have to be sheathed throughout it's length?
--
Kind regards,
Geoff Mills