Building a deck this week, complicated bugger but that's not important.

Going around the existing patio (and the new deck) is a power supply to the
adjacent shed. Its a 2.5mm TO&I cable encased in white PVC flexible
conduit - a bit like the stuff used to tidy up cables behind your PC.

Current owners moved in 3 years ago & it was already there, not mentioned on
survey. Next door seem to have the same thing, nobody is sure how old it
is.

Is this legal & safe? Nothing to do with me really, the deck doesn't go
near it, just seems a bit of a bodge. I thought you had to use armoured
cable?

Should I advise the householder to get it checked out?


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

The Medway Handyman wrote:

Going around the existing patio (and the new deck) is a power supply to the
adjacent shed. Its a 2.5mm TO&I cable encased in white PVC flexible
conduit - a bit like the stuff used to tidy up cables behind your PC.

What is TO&I in this context?



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:
The Medway Handyman wrote:

Going around the existing patio (and the new deck) is a power supply
to the adjacent shed. Its a 2.5mm TO&I cable encased in white PVC
flexible conduit - a bit like the stuff used to tidy up cables
behind your PC.

What is TO&I in this context?

Whoops! T&E I meant :-(



--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

On Wed, 18 Jun 2008 23:04:31 GMT, The Medway Handyman wrote:

Building a deck this week, complicated bugger but that's not important.

Going around the existing patio (and the new deck) is a power supply to the
adjacent shed. Its a 2.5mm TO&I cable encased in white PVC flexible
conduit - a bit like the stuff used to tidy up cables behind your PC.

Current owners moved in 3 years ago & it was already there, not mentioned on
survey. Next door seem to have the same thing, nobody is sure how old it
is.

Is this legal & safe? Nothing to do with me really, the deck doesn't go
near it, just seems a bit of a bodge. I thought you had to use armoured
cable?

Should I advise the householder to get it checked out?

I think you've almost answered your own question.

No offence, but you ain't qualified to offer an expert opinion other than
you have your doubts and, perhaps, it don't look right to you. All you can
do is advise the householder to seek the advice of an electrician. Whether
he does so or not is up to him, but it's then out of your hands.


--
the dot wanderer at tesco dot net

The Medway Handyman wrote:
John Rumm wrote:
The Medway Handyman wrote:

Going around the existing patio (and the new deck) is a power supply
to the adjacent shed. Its a 2.5mm TO&I cable encased in white PVC
flexible conduit - a bit like the stuff used to tidy up cables
behind your PC.
What is TO&I in this context?

Whoops! T&E I meant :-(


Well the main risks with T&E outside is exposure to sunlight and lack of
mechanical protection. The fact that it is sleeved in something helps
greatly. However it is impossible to say how good or bad it is without
knowing what the arrangements are made at both the head of the cable,
and what is going on in the shed.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm coughed up some electrons that declared:

The Medway Handyman wrote:
John Rumm wrote:
The Medway Handyman wrote:

Going around the existing patio (and the new deck) is a power supply
to the adjacent shed. Its a 2.5mm TO&I cable encased in white PVC
flexible conduit - a bit like the stuff used to tidy up cables
behind your PC.
What is TO&I in this context?

Whoops! T&E I meant :-(


Well the main risks with T&E outside is exposure to sunlight and lack of
mechanical protection. The fact that it is sleeved in something helps
greatly. However it is impossible to say how good or bad it is without
knowing what the arrangements are made at both the head of the cable,
and what is going on in the shed.


I've just cut off and made safe a bit of T+E dangling between the trees,
feeding some gate lights.

I would estimate it to be about 10-15 years old. It wasn't brittle but the
sheath was noticably harder than it should have been. Don't know how much
longer it would be before it became dangerously hardend, but it was well on
its way.

The PVC round conduit on the last leg to the bulkhead fittings shattered
when I touched it with the strimmer cord (hence the urgency in
disconnecting the circuit) - that was very very brittle.

So yes, sunlight does very much affect PVC, from first hand experience.

Cheers

Tim

On Jun 19, 12:04*am, "The Medway Handyman"
wrote:

Building a deck this week, complicated bugger but that's not important.

Going around the existing patio (and the new deck) is a power supply to the
adjacent shed. *Its a 2.5mm TO&I cable encased in white PVC flexible
conduit - a bit like the stuff used to tidy up cables behind your PC.

Current owners moved in 3 years ago & it was already there, not mentioned on
survey. *Next door seem to have the same thing, nobody is sure how old it
is.

Is this legal & safe? *Nothing to do with me really, the deck doesn't go
near it, just seems a bit of a bodge. *I thought you had to use armoured
cable?

Should I advise the householder to get it checked out?


Loads of sheds are supplied by T&E. It may not meet new install rules
but its standard equipment and works ok, and is normal for existing
installs. You've got conduit too, luxury. No reason to get it checked
- unless there is a reason to get it checked.


NT

On Jun 19, 12:04*am, "The Medway Handyman"
wrote:

Building a deck this week, complicated bugger but that's not important.

Going around the existing patio (and the new deck) is a power supply to the
adjacent shed. *Its a 2.5mm TO&I cable encased in white PVC flexible
conduit - a bit like the stuff used to tidy up cables behind your PC.

Current owners moved in 3 years ago & it was already there, not mentioned on
survey. *Next door seem to have the same thing, nobody is sure how old it
is.

Is this legal & safe? *Nothing to do with me really, the deck doesn't go
near it, just seems a bit of a bodge. *I thought you had to use armoured
cable?

Should I advise the householder to get it checked out?

Loads of sheds are supplied by T&E. It may not meet new install rules
but its standard equipment and works ok, and is normal for existing
installs. You've got conduit too, luxury. No reason to get it checked
- unless there is a reason to get it checked.


NT

In article ,
Tim S writes:
I've just cut off and made safe a bit of T+E dangling between the trees,
feeding some gate lights.

I would estimate it to be about 10-15 years old. It wasn't brittle but the
sheath was noticably harder than it should have been. Don't know how much
longer it would be before it became dangerously hardend, but it was well on
its way.

The PVC round conduit on the last leg to the bulkhead fittings shattered
when I touched it with the strimmer cord (hence the urgency in
disconnecting the circuit) - that was very very brittle.

So yes, sunlight does very much affect PVC, from first hand experience.

I've known a number of lengths of PVC T&E exposed to sunlight,
some of them older than me and dating back almost to the introduction
of PVC wiring. None have deteriorated noticably (unlike me).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Andrew Gabriel coughed up some electrons that declared:

In article ,
Tim S writes:
I've just cut off and made safe a bit of T+E dangling between the trees,
feeding some gate lights.

I would estimate it to be about 10-15 years old. It wasn't brittle but
the sheath was noticably harder than it should have been. Don't know how
much longer it would be before it became dangerously hardend, but it was
well on its way.

The PVC round conduit on the last leg to the bulkhead fittings shattered
when I touched it with the strimmer cord (hence the urgency in
disconnecting the circuit) - that was very very brittle.

So yes, sunlight does very much affect PVC, from first hand experience.

I've known a number of lengths of PVC T&E exposed to sunlight,
some of them older than me and dating back almost to the introduction
of PVC wiring. None have deteriorated noticably (unlike me).


Wonder why the variance?...

My PVC was white, whatever difference that might make...

Tim S wrote:
Andrew Gabriel coughed up some electrons that declared:

In article ,
Tim S writes:
I've just cut off and made safe a bit of T+E dangling between the trees,
feeding some gate lights.

I would estimate it to be about 10-15 years old. It wasn't brittle but
the sheath was noticably harder than it should have been. Don't know how
much longer it would be before it became dangerously hardend, but it was
well on its way.

The PVC round conduit on the last leg to the bulkhead fittings shattered
when I touched it with the strimmer cord (hence the urgency in
disconnecting the circuit) - that was very very brittle.

So yes, sunlight does very much affect PVC, from first hand experience.
I've known a number of lengths of PVC T&E exposed to sunlight,
some of them older than me and dating back almost to the introduction
of PVC wiring. None have deteriorated noticably (unlike me).


Wonder why the variance?...

My PVC was white, whatever difference that might make...

There are numerous makers of PVC cable, and they are not all then same
even when new. Some are much softer to strip and cut than others for
example. Most of them are affected by sunlight in some way, but to what
extent varies. Very few will harden so much as to become brittle enough
to shed insulation all by themselves, however after prolonged exposure,
they may become more succeptable to damage when hit or bent. Some will
basically remain as they were when new and just get a bit stiffer.

The main problem with T&E outside is it is not strong enough to bury
directly, and is not that well suited to hanging from a support wire.
Running it in conduit (even plastic) is fine in many cases. It will
usually be ok clipped to a wall on its own.

What you need to watch is that inappropriate use of it is not also an
indication of a lashup in other respects - like inadequate earth fault
protection, or exporting a house earth in inappropriate circumstance.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Sat, 21 Jun 2008 03:45:39 +0100, John Rumm
wrote:


What you need to watch is that inappropriate use of it is not also an
indication of a lashup in other respects - like inadequate earth fault
protection, or exporting a house earth in inappropriate circumstance.

Can you give an outline of "inappropriate circumstances" please John?

EricP wrote:
On Sat, 21 Jun 2008 03:45:39 +0100, John Rumm
wrote:


What you need to watch is that inappropriate use of it is not also an
indication of a lashup in other respects - like inadequate earth fault
protection, or exporting a house earth in inappropriate circumstance.

Can you give an outline of "inappropriate circumstances" please John?

The most likely one would be a house with a TN-C-S (PME) earth - i.e.
one that is derived from the suppliers neutral conductor at the main
cutout in the house. One of the potential faults with these
installations that needs to be given consideration is what happens if
the suppliers neutral were ever disconnected but the live left
unaffected (JCB through cable etc). This would leave the neutral and the
earth floating. Given it would be connected to the live side of the
supply via all your appliances, and there would be no current flowing,
so the potential of the neutral and earth (and by implication the metal
cases of all your appliances) would tend to rise to 240V.

This obviously raises a possible serious shock risk. There are a number
of things than can be done to mitigate the effects of the problem. One
of these[1] is good equipotential bonding - making sure that an
equipotential zone exists in the house that electrically commons
together anything that might acquire a different electrical potential
from the electrical earth/neutral. This has two effects - the fortuitous
earthing of things like water and gas supplies will tend to lower the
touch voltage experienced anyway, and more importantly, if you are
unable to make contact with conductive parts that are at significantly
different voltages, its hard to get a shock in the first place - even if
the things you are touching are all at 240V. The Faraday cage principle.

Now maintaining an equipotential zone is easy enough inside a nice
insulated house. However if you want to feed power and the PME earth to
an outbuilding, you need to also ensure the equipotential zone is
maintained in it as well. So for example if the building had a tap
connected via a metal pipe, that would need a main equipotential bond.
This then has the knock on implication that the earth you supply to the
building needs to be large enough to function as a main bonding
conductor as well as an earth (so 10mm^2 copper equivalent as a
minimum). T&E on its own does not have a suitably sized CPC (earth wire)
to perform this function. The real problem comes with buildings where
there is easy access to an independent earth i.e. something with a bare
soil floor like a greenhouse. Here it is virtually impossible to make
the exported PME earth safe, since you can't control what other
potentials it is possible to make contact with along with the earth. The
solution in these cases is to use the PME earth only for protecting the
submain to the outbuilding but then to isolate it on entry so that it is
unused and inaccessible in the building. You then provide your own earth
connection locally using an earth rod. This makes the outbuilding TT
install[2] in its own right, with its own RCD protection.

[1] Needless to say the supplier will also try to mitigate the dangers
of this fault condition by ensuring they connect their combined neutral
and earth conductor to real earth at a number of separate locations.

More on the subtleties of taking power to outbuildings etc cxan be found
he

http://wiki.diyfaq.org.uk/index.php?...ricity_outside


[2] For info on TT Earthing see:

http://wiki.diyfaq.org.uk/index.php?title=TT_Earthing



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/