Cut a very long story short;!. We need to tap of a small amount of power
from a county car park lighting system for a CCTV unit. This is fed with
a 3 core SWA cable where they have the three conductors arranged as;

Red = Switched Live

Yellow = Earth

Blue = Neutral

They have a box which has a photocell and infra red detector
arrangement that switches the live line to power the lights. What we
need is a continuously available mains supply at one end of this lot
around a 100 metres away.

Question..

Is it OK to change this so that the Yellow now carries the live or swap
that for the Red and make the Yellow the switched live and use the Steel
wire of the SWA cable as the Earth protective conductor?..

So now this becomes;


Red = Permanent live

Yellow = Switched live

Blue = Neutral

SWA wires = Earth



And of course label it all to denote that one is switched and the other
is live etc?..

Cheers..
--
Tony Sayer

tony sayer coughed up some electrons that declared:


Cut a very long story short;!. We need to tap of a small amount of power
from a county car park lighting system for a CCTV unit. This is fed with
a 3 core SWA cable where they have the three conductors arranged as;

Red = Switched Live

Yellow = Earth

Blue = Neutral

They have a box which has a photocell and infra red detector
arrangement that switches the live line to power the lights. What we
need is a continuously available mains supply at one end of this lot
around a 100 metres away.

Question..

Is it OK to change this so that the Yellow now carries the live or swap
that for the Red and make the Yellow the switched live and use the Steel
wire of the SWA cable as the Earth protective conductor?..

So now this becomes;


Red = Permanent live

Yellow = Switched live

Blue = Neutral

SWA wires = Earth



And of course label it all to denote that one is switched and the other
is live etc?..

Cheers..

I think the real question is will the SWA be suitable for the earth
provision? No problem that I can see with the alterations to the use of
cores - just sleeve red and black as appropriate.

The answer is probably. How big is the cable and can you estimate how long
the longest run is, back to the breaker? What is the breaker (type and
amps) There's some stuff in the Wiki that covers some of this.

Your stated colour scheme is quite sensible (= predictable to the future
uninitiated).

Also, do all the existing lights reliably have the cable armour made off
properly *and* is the armour connected to the earth terminal and/or
metalwork of the lamp (if any)? They might just have earthed the armour at
the feed end, if they knew they were going to use one of the cores as the
CPC...

Sure there might be some more gotchas - hang about for some extra
opinions...

Cheers

Tim

tony sayer wrote:
Cut a very long story short;!. We need to tap of a small amount of power
from a county car park lighting system for a CCTV unit. This is fed with
a 3 core SWA cable where they have the three conductors arranged as;

Red = Switched Live

Yellow = Earth

Blue = Neutral

They have a box which has a photocell and infra red detector
arrangement that switches the live line to power the lights. What we
need is a continuously available mains supply at one end of this lot
around a 100 metres away.

Question..

Is it OK to change this so that the Yellow now carries the live or swap
that for the Red and make the Yellow the switched live and use the Steel
wire of the SWA cable as the Earth protective conductor?..

So now this becomes;


Red = Permanent live

Yellow = Switched live

Blue = Neutral

SWA wires = Earth



And of course label it all to denote that one is switched and the other
is live etc?..

Cheers..

Sounds good to me. I wonder why they didn't use two-core SWA in the
first place? Good that they didn't, hey?

You might need to get your knickers in a twist with labelling dual
colour schemes if your new cabling is brown/blue or brown/black/grey...

tony sayer wrote:
Cut a very long story short;!. We need to tap of a small amount of power
from a county car park lighting system for a CCTV unit. This is fed with
a 3 core SWA cable where they have the three conductors arranged as;

Red = Switched Live

Yellow = Earth

Check this has not been paralleled with the armour!


So now this becomes;


Red = Permanent live

Yellow = Switched live

Blue = Neutral

SWA wires = Earth

Sheath with appropriate a colours and it ought to be ok. You will need
to check the earth (i.e. armour) continuity.

More relevant stuff he

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

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



--
Cheers,

John.

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

Dave Osborne wrote:
tony sayer wrote:
Cut a very long story short;!. We need to tap of a small amount of power
from a county car park lighting system for a CCTV unit. This is fed with
a 3 core SWA cable where they have the three conductors arranged as;

Red = Switched Live

Yellow = Earth

Blue = Neutral

They have a box which has a photocell and infra red detector
arrangement that switches the live line to power the lights. What we
need is a continuously available mains supply at one end of this lot
around a 100 metres away.

Question..

Is it OK to change this so that the Yellow now carries the live or swap
that for the Red and make the Yellow the switched live and use the Steel
wire of the SWA cable as the Earth protective conductor?..

So now this becomes;


Red = Permanent live

Yellow = Switched live

Blue = Neutral

SWA wires = Earth



And of course label it all to denote that one is switched and the other
is live etc?..

Cheers..

Sounds good to me. I wonder why they didn't use two-core SWA in the
first place? Good that they didn't, hey?

You might need to get your knickers in a twist with labelling dual
colour schemes if your new cabling is brown/blue or brown/black/grey...

It would work but it would be illegal in my opinion.

Use of a battery which charges when the lights on sounds the best idea
to me.

[g]

george (dicegeorge) wrote:


Dave Osborne wrote:
tony sayer wrote:
Cut a very long story short;!. We need to tap of a small amount of power
from a county car park lighting system for a CCTV unit. This is fed with
a 3 core SWA cable where they have the three conductors arranged as;

Red = Switched Live

Yellow = Earth

Blue = Neutral

They have a box which has a photocell and infra red detector
arrangement that switches the live line to power the lights. What we
need is a continuously available mains supply at one end of this lot
around a 100 metres away.

Question..

Is it OK to change this so that the Yellow now carries the live or swap
that for the Red and make the Yellow the switched live and use the Steel
wire of the SWA cable as the Earth protective conductor?..

So now this becomes;


Red = Permanent live

Yellow = Switched live

Blue = Neutral

SWA wires = Earth



And of course label it all to denote that one is switched and the other
is live etc?..

Cheers..

Sounds good to me. I wonder why they didn't use two-core SWA in the
first place? Good that they didn't, hey?

You might need to get your knickers in a twist with labelling dual
colour schemes if your new cabling is brown/blue or brown/black/grey...

It would work but it would be illegal in my opinion.

Which bit? and illegal why?



--
Cheers,

John.

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

"tony sayer" wrote in message
...

Cut a very long story short;!. We need to tap of a small amount of power
from a county car park lighting system for a CCTV unit. This is fed with
a 3 core SWA cable where they have the three conductors arranged as;

Red = Switched Live

Yellow = Earth

Blue = Neutral

They have a box which has a photocell and infra red detector
arrangement that switches the live line to power the lights. What we
need is a continuously available mains supply at one end of this lot
around a 100 metres away.

Question..

Is it OK to change this so that the Yellow now carries the live or swap
that for the Red and make the Yellow the switched live and use the Steel
wire of the SWA cable as the Earth protective conductor?..

So now this becomes;


Red = Permanent live

Yellow = Switched live

Blue = Neutral

SWA wires = Earth



And of course label it all to denote that one is switched and the other
is live etc?..

That is three-phase cable (old colours) and the sheath would have been the
intended earth connection had it been used for three-phase. Provided the
connections have all been properly made, there would be no problem with your
suggested changes. I would put a red sleeve over the ends of the yellow
wire, in case any of the labels come off or become illegible.

Colin Bignell

John Rumm wrote:
george (dicegeorge) wrote:


Dave Osborne wrote:
tony sayer wrote:
Cut a very long story short;!. We need to tap of a small amount of
power
from a county car park lighting system for a CCTV unit. This is fed
with
a 3 core SWA cable where they have the three conductors arranged as;

Red = Switched Live

Yellow = Earth

Blue = Neutral

They have a box which has a photocell and infra red detector
arrangement that switches the live line to power the lights. What we
need is a continuously available mains supply at one end of this lot
around a 100 metres away.

Question..

Is it OK to change this so that the Yellow now carries the live or swap
that for the Red and make the Yellow the switched live and use the
Steel
wire of the SWA cable as the Earth protective conductor?..

So now this becomes;


Red = Permanent live

Yellow = Switched live

Blue = Neutral

SWA wires = Earth



And of course label it all to denote that one is switched and the other
is live etc?..

Cheers..

Sounds good to me. I wonder why they didn't use two-core SWA in the
first place? Good that they didn't, hey?

You might need to get your knickers in a twist with labelling dual
colour schemes if your new cabling is brown/blue or brown/black/grey...

It would work but it would be illegal in my opinion.

Which bit? and illegal why?



I had assumed the yellow was designed to be an earth,
and the casing for physical protection,
but now I realise I was wrong,
the 3 wires were all designed for live 3 phase,
so perhaps it is OK,
if all the connections are changed and checked.

whoops

[g]

george (dicegeorge) coughed up some electrons that declared:


I had assumed the yellow was designed to be an earth,
and the casing for physical protection,
but now I realise I was wrong,
the 3 wires were all designed for live 3 phase,
so perhaps it is OK,
if all the connections are changed and checked.

whoops

[g]

Yes - that main thing is that the armour has continuity to all parts where a
CPC is expected (as I said previously) *and* that the L-E resistance
(R1+R2) is sufficiently low that on a L-E fault, th ebreaker opens within
the correct time which is either[1] 0.4s or 5s depending on circuit
function and type/size...

Usually this works for smaller sizes of SWA but I'd hate to take things at
face value, which is why I asked if the max circuit length, SWA size and
breaker size/type are known

[1] There's a 3rd timing, IIRC, but not one that's relevant to me right now
so I've forgotton.

Cheers

Tim

"John Rumm" wrote in message
o.uk...
tony sayer wrote:
Cut a very long story short;!. We need to tap of a small amount of power
from a county car park lighting system for a CCTV unit. This is fed with
a 3 core SWA cable where they have the three conductors arranged as;

Red = Switched Live

Yellow = Earth

Check this has not been paralleled with the armour!


So now this becomes;


Red = Permanent live

Yellow = Switched live

Blue = Neutral

SWA wires = Earth

Sheath with appropriate a colours and it ought to be ok. You will need to
check the earth (i.e. armour) continuity.

More relevant stuff he

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

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



and here

http://www.gadsolutions.biz/regulations/swa-as-the-cpc

Adam

And of course label it all to denote that one is switched and the other
is live etc?..

That is three-phase cable (old colours) and the sheath would have been the
intended earth connection had it been used for three-phase. Provided the
connections have all been properly made, there would be no problem with your
suggested changes. I would put a red sleeve over the ends of the yellow
wire, in case any of the labels come off or become illegible.

Colin Bignell



OK thanks to all who replied..

No, the lights aren't on long enough for battery charging and we have
tried that as one location does have a lump of CAT 5 cable which is
pushing the length for the CAT 5 spec at 115 metres and thats through a
very thin duct and it only just went in there with no problems to get
power or another cable is a no go..We tried POE but the drop is too
great even at 50 odd volts..

And we need mains volts for the cameras at different voltages and for a
remote network VCR and a wireless link, we could I suppose have a
collection of DC to DC converters but its all messy and whenever you
just need mains to plug in the test monitor!...

The "3 conductors and sheath earth" principle is a good one so thats
fine, in fact we'll more then likely have spare earth stake or so in
order to cope with lightning discharge potentials as this is in a hilly
place;!

The switched line is fused at 16 amps due to the 2 kW lighting load and
I think the cable is pushing it for that spec anyway!

In fact where this comes off the SWA cable they who put it in originally
have just used twin and earth to feed the lights with no extra
protection so we'll sort that and this being publicly accessible too!..

But the continuous live will be fused at 6 amps as were never likely to
take more than a half amp off it anyway and the whole will be on a RCD
as muggings will be working on this alone .. and out in the wilds so)

And what does the team think re the actual old cable colours and
sleeving it with the new ones?.

It would seem more logical to me to have Red as live and Yellow as
switched live..

Is there a colour code standard for this anyway live line and switched
in this sort of allocation?..

cheers...
--
Tony Sayer

On Sat, 20 Jun 2009 12:46:34 +0100 someone who may be tony sayer
wrote this:-

In fact where this comes off the SWA cable they who put it in originally
have just used twin and earth to feed the lights with no extra
protection so we'll sort that and this being publicly accessible too!..

The joints are made outside the lighting columns? In what and
mounted where?

I suggest that you test the armour carefully with a proper tester,
to make sure it is up to the job.
And what does the team think re the actual old cable colours and
sleeving it with the new ones?.

I would sleeve the cores in the correct colours, rather then harking
back to the days of old.

Is there a colour code standard for this anyway live line and switched
in this sort of allocation?..

I would sleeve them both in brown. I would use the red as the
permanent live and the yellow as the switched live.


--
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 article , David Hansen
scribeth thus
On Sat, 20 Jun 2009 12:46:34 +0100 someone who may be tony sayer
wrote this:-

In fact where this comes off the SWA cable they who put it in originally
have just used twin and earth to feed the lights with no extra
protection so we'll sort that and this being publicly accessible too!..

The joints are made outside the lighting columns? In what and
mounted where?

The lighting "columns" are in fact old telephone poles and are 20 foot
high. They had to use them and limit the height at the insistence of the
planners who have a thing about light pollution;!..

The lights are identical to the halogen floodlights that you'd have at
home. But without the switch. Two on the one pole one on the other.

The cable/s come from underground clipped to the wooden pole then into
small plastic encloses, the cables to the lights are done in 1.0 mm T&E
just clipped to the poles with no extra protection..


I suggest that you test the armour carefully with a proper tester,
to make sure it is up to the job.

Indeed..

And what does the team think re the actual old cable colours and
sleeving it with the new ones?.

I would sleeve the cores in the correct colours, rather then harking
back to the days of old.

Is there a colour code standard for this anyway live line and switched
in this sort of allocation?..

I would sleeve them both in brown. I would use the red as the
permanent live and the yellow as the switched live.


Right tho that doesn't sound too logical, or does one assume that both
are to be treated as live?..
--
Tony Sayer

http://www.gadsolutions.biz/regulations/swa-as-the-cpc

Adam



OK according to their cable calculator this setup is from electricity supply
in a small brick built housing to the first light pole is 20 metres..then
another pole 70 metres, and the CCTV supply a further 10 metres.

Total load for Three core PVC SWA which in effect will be two core is 1.5
kW total load plus the 10- watts for the CCTV .. but as only 1 kW of light is
on that pole then thats all OK for that bit as the existing cable is 1.5 so
thats a max load capability of 3.5 kW over 20 metres so assume a total load
capacity of say 2 kW then to the first pole thats well within .. the second
pole will draw 1 kW well 500 watts of light and a max of 500 to the other
equipment which will be far less then that..

So 70- metres from the fist pole will still be within the capabilities of the
1.5 cable?.. which is taking 2 kW from the supply to the first pole then 1 kW
of light on that then a further 70 metres to the second pole with a 500 watts
light load and up to say 500 watts absolute max for the other equipment?..

What do Queens regs say about that end having a an isolator and a single MCB
of say 6 amps feeding a dual 13 amp outlet socket not that anyone would plug
any more load in that then say 100 watts total?..

If it were possible to connect the gear in there directly to a cable outlet
then I'd do that but as their bloody wall warts .. not possible;(..
--
Tony Sayer

and here

http://www.gadsolutions.biz/regulations/swa-as-the-cpc

Adam


OK according to their cable calculator this setup is from electricity supply
in a small brick built housing to the first light pole is 20 metres..then
another pole 70 metres, and the CCTV supply a further 10 metres.

Total load for Three core PVC SWA which in effect will be two core is 1.5
kW total load plus the 100 watts for the CCTV .. but as only 1 kW of light is
on that pole then thats all OK for that bit as the existing cable is 1.5 so
thats a max load capability of 3.5 kW over 20 metres so assume a total load
capacity of say 2 kW then to the first pole thats well within .. the second
pole will draw 1 kW well 500 watts of light and a max of 500 to the other
equipment which will be far less then that..

So 70 metres from the fist pole will still be within the capabilities of the
1.5 cable?.. which is taking 2 kW from the supply to the first pole then 1 kW
of light on that then a further 70 metres to the second pole with a 500 watts
light load and up to say 500 watts absolute max for the other equipment?..


What do Queens regs say about that end having an isolator and a single MCB
of say 6 amps feeding a dual 13 amp outlet socket not that anyone would plug
any more load in that then say 100 watts total?..

If it were possible to connect the gear in there directly to a cable outlet
then I'd do that but as their bloody wall warts .. not possible;(..
--
Tony Sayer

On Sat, 20 Jun 2009 14:49:41 +0100 someone who may be tony sayer
wrote this:-

The lights are identical to the halogen floodlights that you'd have at
home. But without the switch. Two on the one pole one on the other.

I would replace them with high pressure sodium lights, powerful
enough to get the necessary light level for the CCTV in the whole
area. I assume the CCTV is not infra-red.

The lights will presumably be left on for long periods with CCTV, in
which case (as well as making the electricity meter spin round
quickly) they will need to budget for someone to constantly replace
the failed lamps. Having lamps come on suddenly will probably cause
the camera trouble for a few seconds, probably at the worst moment.

The cable/s come from underground clipped to the wooden pole then into
small plastic encloses,

Is the continuity of the armour maintained across the small plastic
enclosures? If not then after the first plastic enclosure the armour
is floating.

the cables to the lights are done in 1.0 mm T&E
just clipped to the poles with no extra protection..

Hmmmm. I would either fit conduit, or replace with cable suitable
for outdoor use.

I would sleeve them both in brown. I would use the red as the
permanent live and the yellow as the switched live.


Right tho that doesn't sound too logical, or does one assume that both
are to be treated as live?..

It sounds logical to me. One will be live at all times, the other
will be live when the lamps (either the current ones or new ones)
are energised. Whether there is a detector or photocell energising
this wire I would treat it as live at all times, unless I had taken
steps to make sure it cannot be energised.

Brown, black and grey (and numbering systems) are used to
differentiate between different phases on multi-phase AC circuits
(for DC circuits they do much the same thing). You are working on a
single phase circuit.





--
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

george (dicegeorge) wrote:


John Rumm wrote:
george (dicegeorge) wrote:


Dave Osborne wrote:
tony sayer wrote:
Cut a very long story short;!. We need to tap of a small amount of
power
from a county car park lighting system for a CCTV unit. This is fed
with
a 3 core SWA cable where they have the three conductors arranged as;

Red = Switched Live

Yellow = Earth

Blue = Neutral

They have a box which has a photocell and infra red detector
arrangement that switches the live line to power the lights. What we
need is a continuously available mains supply at one end of this lot
around a 100 metres away.

Question..

Is it OK to change this so that the Yellow now carries the live or
swap
that for the Red and make the Yellow the switched live and use the
Steel
wire of the SWA cable as the Earth protective conductor?..

So now this becomes;


Red = Permanent live

Yellow = Switched live

Blue = Neutral

SWA wires = Earth



And of course label it all to denote that one is switched and the
other
is live etc?..

Cheers..

Sounds good to me. I wonder why they didn't use two-core SWA in the
first place? Good that they didn't, hey?

You might need to get your knickers in a twist with labelling dual
colour schemes if your new cabling is brown/blue or brown/black/grey...

It would work but it would be illegal in my opinion.

Which bit? and illegal why?



I had assumed the yellow was designed to be an earth,
and the casing for physical protection,
but now I realise I was wrong,
the 3 wires were all designed for live 3 phase,
so perhaps it is OK,

Yup, if you just want live, neutral and earth you would usually use a
two core swa and use the screen as the earth. Some applications may
however require use of a core in addition to the screen. The colours are
frequently not what you would ideally want and will need over sleeving.

Its a particular nuisance when you have a mixture of old and new colours
as well as a mixture of two and three core, where you notionally have
black and blue both potentially being line and neutral. (in these cases
I sleeve new cable to match the old colours)



--
Cheers,

John.

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

tony sayer wrote:
http://www.gadsolutions.biz/regulations/swa-as-the-cpc

Adam



OK according to their cable calculator this setup is from electricity supply
in a small brick built housing to the first light pole is 20 metres..then
another pole 70 metres, and the CCTV supply a further 10 metres.

Total load for Three core PVC SWA which in effect will be two core is 1.5
kW total load plus the 10- watts for the CCTV .. but as only 1 kW of light is
on that pole then thats all OK for that bit as the existing cable is 1.5 so
thats a max load capability of 3.5 kW over 20 metres so assume a total load
capacity of say 2 kW then to the first pole thats well within .. the second
pole will draw 1 kW well 500 watts of light and a max of 500 to the other
equipment which will be far less then that..

So we have :

----20m---------P1-------70m----------P2----10m-----CCTV


Is it 1kW on pole 1, 500W on pole 2, and an allowance of 500W on the CCTV?

Voltage drop is an issue here. With 1000W load (4.35A) at P1 you have
2.52V of drop at that pole. With 500W (2.17A) at P2 you have another
4.4V of drop there (assuming a drop of 29mV/A/m).

So by the second pole you are already a little under spec on voltage to
be strictly in compliance with the regs. In terms of cable carrying
capacity the cable is fine.

You need to check disconnection times as well. What earthing system is
at the head end of the cable?

So 70- metres from the fist pole will still be within the capabilities of the
1.5 cable?.. which is taking 2 kW from the supply to the first pole then 1 kW
of light on that then a further 70 metres to the second pole with a 500 watts
light load and up to say 500 watts absolute max for the other equipment?..

What do Queens regs say about that end having a an isolator and a single MCB
of say 6 amps feeding a dual 13 amp outlet socket not that anyone would plug
any more load in that then say 100 watts total?..

As long as you label the socket appropriately you should be ok.

If it were possible to connect the gear in there directly to a cable outlet
then I'd do that but as their bloody wall warts .. not possible;(..


--
Cheers,

John.

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

"tony sayer" wrote in message
...

and here

http://www.gadsolutions.biz/regulations/swa-as-the-cpc

Adam


OK according to their cable calculator this setup is from electricity
supply
in a small brick built housing to the first light pole is 20 metres..then
another pole 70 metres, and the CCTV supply a further 10 metres.

Total load for Three core PVC SWA which in effect will be two core is
1.5
kW total load plus the 100 watts for the CCTV .. but as only 1 kW of light
is
on that pole then thats all OK for that bit as the existing cable is 1.5
so
thats a max load capability of 3.5 kW over 20 metres so assume a total
load
capacity of say 2 kW then to the first pole thats well within .. the
second
pole will draw 1 kW well 500 watts of light and a max of 500 to the other
equipment which will be far less then that..

So 70 metres from the fist pole will still be within the capabilities of
the
1.5 cable?.. which is taking 2 kW from the supply to the first pole then 1
kW
of light on that then a further 70 metres to the second pole with a 500
watts
light load and up to say 500 watts absolute max for the other equipment?..


What do Queens regs say about that end having an isolator and a single
MCB
of say 6 amps feeding a dual 13 amp outlet socket not that anyone would
plug
any more load in that then say 100 watts total?..

It is a non-standard but electrically safe circuit that only a competent
person can access. No problem IMHO.



If it were possible to connect the gear in there directly to a cable
outlet
then I'd do that but as their bloody wall warts .. not possible;(..

I have seen more 13A loft sockets running from the upstairs lighting than
you would believe.
The 6A MCB (or 5A fuse) for the lighting circuit provides all the protection
needed.

Adam

David Hansen coughed up some electrons that declared:


I would sleeve them both in brown. I would use the red as the
permanent live and the yellow as the switched live.

I would disagree on the sleeving - this cable is to "old" preharmonised
colours, therefor the sleeving should follow the same system (red and
black). That's what we were taught.

Cheers

Tim

"John Rumm" wrote in message
o.uk...
george (dicegeorge) wrote:


John Rumm wrote:
george (dicegeorge) wrote:


Dave Osborne wrote:
tony sayer wrote:
Cut a very long story short;!. We need to tap of a small amount of
power
from a county car park lighting system for a CCTV unit. This is fed
with
a 3 core SWA cable where they have the three conductors arranged as;

Red = Switched Live

Yellow = Earth

Blue = Neutral

They have a box which has a photocell and infra red detector
arrangement that switches the live line to power the lights. What we
need is a continuously available mains supply at one end of this lot
around a 100 metres away.

Question..

Is it OK to change this so that the Yellow now carries the live or
swap
that for the Red and make the Yellow the switched live and use the
Steel
wire of the SWA cable as the Earth protective conductor?..

So now this becomes;


Red = Permanent live

Yellow = Switched live

Blue = Neutral

SWA wires = Earth



And of course label it all to denote that one is switched and the
other
is live etc?..

Cheers..

Sounds good to me. I wonder why they didn't use two-core SWA in the
first place? Good that they didn't, hey?

You might need to get your knickers in a twist with labelling dual
colour schemes if your new cabling is brown/blue or
brown/black/grey...

It would work but it would be illegal in my opinion.

Which bit? and illegal why?



I had assumed the yellow was designed to be an earth,
and the casing for physical protection,
but now I realise I was wrong,
the 3 wires were all designed for live 3 phase,
so perhaps it is OK,

Yup, if you just want live, neutral and earth you would usually use a two
core swa and use the screen as the earth. Some applications may however
require use of a core in addition to the screen. The colours are
frequently not what you would ideally want and will need over sleeving.

Its a particular nuisance when you have a mixture of old and new colours
as well as a mixture of two and three core, where you notionally have
black and blue both potentially being line and neutral. (in these cases I
sleeve new cable to match the old colours)



I usually sleeve the old colours with the new colours where they meet. My
theory is that red sleeving will become harder to buy in the future.

As long as each cable is correctly identified with sleeving in either the
old or new colour scheme where old meets new then there is no problem.

Adam

What do Queens regs say about that end having an isolator and a single
MCB
of say 6 amps feeding a dual 13 amp outlet socket not that anyone would
plug
any more load in that then say 100 watts total?..

It is a non-standard but electrically safe circuit that only a competent
person can access. No problem IMHO.


It won't be, all bits have chubb locked enclosures, well the important
bits and only I have the key..


If it were possible to connect the gear in there directly to a cable
outlet
then I'd do that but as their bloody wall warts .. not possible;(..

I have seen more 13A loft sockets running from the upstairs lighting than
you would believe.

Yes we need this to be done correctly..

The 6A MCB (or 5A fuse) for the lighting circuit provides all the protection
needed.


OK...

Adam




--
Tony Sayer

In article , John
Rumm scribeth thus
tony sayer wrote:
http://www.gadsolutions.biz/regulations/swa-as-the-cpc

Adam



OK according to their cable calculator this setup is from electricity supply
in a small brick built housing to the first light pole is 20 metres..then
another pole 70 metres, and the CCTV supply a further 10 metres.

Total load for Three core PVC SWA which in effect will be two core is 1.5
kW total load plus the 10- watts for the CCTV .. but as only 1 kW of light is
on that pole then thats all OK for that bit as the existing cable is 1.5 so
thats a max load capability of 3.5 kW over 20 metres so assume a total load
capacity of say 2 kW then to the first pole thats well within .. the second
pole will draw 1 kW well 500 watts of light and a max of 500 to the other
equipment which will be far less then that..

So we have :

----20m---------P1-------70m----------P2----10m-----CCTV


Is it 1kW on pole 1, 500W on pole 2, and an allowance of 500W on the CCTV?

Yes 'tho the CCTV is prolly nearer to 60 watts ..


Voltage drop is an issue here. With 1000W load (4.35A) at P1 you have
2.52V of drop at that pole. With 500W (2.17A) at P2 you have another
4.4V of drop there (assuming a drop of 29mV/A/m).

So by the second pole you are already a little under spec on voltage to
be strictly in compliance with the regs. In terms of cable carrying
capacity the cable is fine.

Well it just means the light is a bit dimmer then it might, otherwise be
but no real problem.. The CCTV gear is on mains switch mode's that go
from 100 to 230 volts .. so quite tolerant..



You need to check disconnection times as well. What earthing system is
at the head end of the cable?

Haven't looked a Earth wire runs off somewhere and theres the "earth" on
the supply cable.. But walloping a few Furse stakes in here and there
isn't a problem..

So 70- metres from the fist pole will still be within the capabilities of the
1.5 cable?.. which is taking 2 kW from the supply to the first pole then 1 kW
of light on that then a further 70 metres to the second pole with a 500 watts
light load and up to say 500 watts absolute max for the other equipment?..

What do Queens regs say about that end having a an isolator and a single MCB
of say 6 amps feeding a dual 13 amp outlet socket not that anyone would plug
any more load in that then say 100 watts total?..

As long as you label the socket appropriately you should be ok.

OK..cheers..


If it were possible to connect the gear in there directly to a cable outlet
then I'd do that but as their bloody wall warts .. not possible;(..



--
Tony Sayer

In article , David Hansen
scribeth thus
On Sat, 20 Jun 2009 14:49:41 +0100 someone who may be tony sayer
wrote this:-

The lights are identical to the halogen floodlights that you'd have at
home. But without the switch. Two on the one pole one on the other.

I would replace them with high pressure sodium lights, powerful
enough to get the necessary light level for the CCTV in the whole
area. I assume the CCTV is not infra-red.

The powers that be don't want them to be on all the time, otherwise I
expect that would have been done by now seems someone thinks it will
light pollute the night sky and blind the wildlife..

As to the CCTV its amazing what modern cameras can pick up in low
light..

The lights are switched bu a rather complex overkill control system..


The lights will presumably be left on for long periods with CCTV, in
which case (as well as making the electricity meter spin round
quickly) they will need to budget for someone to constantly replace
the failed lamps. Having lamps come on suddenly will probably cause
the camera trouble for a few seconds, probably at the worst moment.

The cable/s come from underground clipped to the wooden pole then into
small plastic encloses,

Is the continuity of the armour maintained across the small plastic
enclosures? If not then after the first plastic enclosure the armour
is floating.


Have to check that I expect that the existing Yellow conductor is doing
that..

the cables to the lights are done in 1.0 mm T&E
just clipped to the poles with no extra protection..

Hmmmm. I would either fit conduit, or replace with cable suitable
for outdoor use.

Indeed..

I would sleeve them both in brown. I would use the red as the
permanent live and the yellow as the switched live.


Right tho that doesn't sound too logical, or does one assume that both
are to be treated as live?..

It sounds logical to me. One will be live at all times, the other
will be live when the lamps (either the current ones or new ones)
are energised. Whether there is a detector or photocell energising
this wire I would treat it as live at all times, unless I had taken
steps to make sure it cannot be energised.

Ok..


Brown, black and grey (and numbering systems) are used to
differentiate between different phases on multi-phase AC circuits
(for DC circuits they do much the same thing). You are working on a
single phase circuit.

Ok 'tho brown black and grey seems a grey area..






--
Tony Sayer

Bancom Communications U.K. Tel+44 1223 566577 Fax+44 1223 566588

4 Wingate close, Cambridge, England, CB2 9HW E-Mail

In article , scribeth
thus
On 20 Jun,
David Hansen wrote:

I would replace them with high pressure sodium lights, powerful
enough to get the necessary light level for the CCTV in the whole
area. I assume the CCTV is not infra-red.

Metal halide wuld give a more natural colour rendition, akin to the existing
lights, but would have a lot of the advantaged of the sodium lamps. They
would probably give less light spill, and please the planning authorities and
neighbours.


I expect they would but for a lot of the night no ones there at all
except the bunnies.. And foxy woxy;!..
--
Tony Sayer

In article , Tim S
scribeth thus
David Hansen coughed up some electrons that declared:


I would sleeve them both in brown. I would use the red as the
permanent live and the yellow as the switched live.

I would disagree on the sleeving - this cable is to "old" preharmonised
colours, therefor the sleeving should follow the same system (red and
black). That's what we were taught.

Cheers

Tim

OK, 'tho I note the various comments on that but somehow Blue, Red, and
Yellow seem a bit more logical..

Perhaps we'll have to put it to the vote)..
--
Tony Sayer

On Sat, 20 Jun 2009 14:49:41 +0100, tony sayer wrote:

snip

The lighting "columns" are in fact old telephone poles and are 20 foot
high. They had to use them and limit the height at the insistence of the
planners who have a thing about light pollution;!..

snip


Be careful. If the telegraph poles are "reclaimed" they may be
impregnated with creosote, which reacts with PVC over a period of time
IIRC. That wouldn't be good for unprotected cable.

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info
Filtering everything posted from googlegroups to kill spam.

On Sat, 20 Jun 2009 19:22:19 +0100 someone who may be tony sayer
wrote this:-

As to the CCTV its amazing what modern cameras can pick up in low
light..

The question is how the cameras react to the sudden switch on of
high lighting levels. Some produce a white image for several
seconds, until the camera adjusts itself. If the lights are
activated by people/animals then that white image may be just at the
time when you would most like to see/record the image.



--
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 article , David Hansen
scribeth thus
On Sat, 20 Jun 2009 19:22:19 +0100 someone who may be tony sayer
wrote this:-

As to the CCTV its amazing what modern cameras can pick up in low
light..

The question is how the cameras react to the sudden switch on of
high lighting levels. Some produce a white image for several
seconds, until the camera adjusts itself. If the lights are
activated by people/animals then that white image may be just at the
time when you would most like to see/record the image.



Very well the new ones do, these seem to get better with development....
--
Tony Sayer

In article , mick
scribeth thus
On Sat, 20 Jun 2009 14:49:41 +0100, tony sayer wrote:

snip

The lighting "columns" are in fact old telephone poles and are 20 foot
high. They had to use them and limit the height at the insistence of the
planners who have a thing about light pollution;!..

snip


Be careful. If the telegraph poles are "reclaimed" they may be
impregnated with creosote, which reacts with PVC over a period of time
IIRC. That wouldn't be good for unprotected cable.

^

These are quite some age and are ex GPO there doesn't seem to be any
noticeable deterioration exposed to the air and public!..
--
Tony Sayer

"David Hansen" wrote in message
...
On Sat, 20 Jun 2009 12:46:34 +0100 someone who may be tony sayer
wrote this
.....
And what does the team think re the actual old cable colours and
sleeving it with the new ones?.

I would sleeve the cores in the correct colours, rather then harking
back to the days of old. ...

There is absolutely no reason to do so. Existing installations can continue
to use the old colours and the proposed red = live / yellow = switched live
/ blue = neutral is exactly the way the circuits should be wired.

Colin Bignell

On Sun, 21 Jun 2009 16:30:53 +0100 someone who may be "nightjar"
cpb@insert my surname here.me.uk wrote this:-

I would sleeve the cores in the correct colours, rather then harking
back to the days of old. ...

There is absolutely no reason to do so.

In your opinion, which you are entitled to.


--
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 Sun, 21 Jun 2009 10:31:52 +0100, tony sayer wrote:

In article , mick
scribeth thus
On Sat, 20 Jun 2009 14:49:41 +0100, tony sayer wrote:

snip

The lighting "columns" are in fact old telephone poles and are 20 foot
high. They had to use them and limit the height at the insistence of
the planners who have a thing about light pollution;!..

snip


Be careful. If the telegraph poles are "reclaimed" they may be
impregnated with creosote, which reacts with PVC over a period of time
IIRC. That wouldn't be good for unprotected cable.

^

These are quite some age and are ex GPO there doesn't seem to be any
noticeable deterioration exposed to the air and public!..


duh... yeah... :-)

The pole will be fine - the pvc insulation may get it's plasticisers
leached out by the creosote, making it dry and brittle. Eventually the
pvc drops off, leaving bare copper. That's if I've understood it
correctly. Of course, it *may* not be creosote that they used and the pvc
formulation *may* be different now. Personally, I've never run pvc cable
against creosoted telegraph poles. :-) Some nice galv conduit wouldn't
be amiss & would also protect the wiring against being nibbled by mice
etc.

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info
Filtering everything posted from googlegroups to kill spam.

David Hansen wrote:
On Sun, 21 Jun 2009 16:30:53 +0100 someone who may be "nightjar"
cpb@insert my surname here.me.uk wrote this:-

I would sleeve the cores in the correct colours, rather then harking
back to the days of old. ...
There is absolutely no reason to do so.

In your opinion, which you are entitled to.

When adding a small amount of new colour wiring to a large amount of
old, it makes more sense to sleeve the new to match the old rather than
the other way around. That way you only need add sleeving to new wires
and not existing ones.

--
Cheers,

John.

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

In article , mick
scribeth thus
On Sun, 21 Jun 2009 10:31:52 +0100, tony sayer wrote:

In article , mick
scribeth thus
On Sat, 20 Jun 2009 14:49:41 +0100, tony sayer wrote:

snip

The lighting "columns" are in fact old telephone poles and are 20 foot
high. They had to use them and limit the height at the insistence of
the planners who have a thing about light pollution;!..

snip


Be careful. If the telegraph poles are "reclaimed" they may be
impregnated with creosote, which reacts with PVC over a period of time
IIRC. That wouldn't be good for unprotected cable.

^

These are quite some age and are ex GPO there doesn't seem to be any
noticeable deterioration exposed to the air and public!..


duh... yeah... :-)

The pole will be fine - the pvc insulation may get it's plasticisers
leached out by the creosote, making it dry and brittle. Eventually the
pvc drops off, leaving bare copper. That's if I've understood it
correctly. Of course, it *may* not be creosote that they used and the pvc
formulation *may* be different now. Personally, I've never run pvc cable
against creosoted telegraph poles. :-) Some nice galv conduit wouldn't
be amiss & would also protect the wiring against being nibbled by mice
etc.

Yep thats what is now intended
--
Tony Sayer

When I tried to do this at a mates house, provide unswitched live on the
yellow conductor I found the yellow was bonded to the SWA armour somewhere,
possibly an undergorund junction box so was not possible to do.

"tony sayer" wrote in message
...

Cut a very long story short;!. We need to tap of a small amount of power
from a county car park lighting system for a CCTV unit. This is fed with
a 3 core SWA cable where they have the three conductors arranged as;

Red = Switched Live

Yellow = Earth

Blue = Neutral

They have a box which has a photocell and infra red detector
arrangement that switches the live line to power the lights. What we
need is a continuously available mains supply at one end of this lot
around a 100 metres away.

Question..

Is it OK to change this so that the Yellow now carries the live or swap
that for the Red and make the Yellow the switched live and use the Steel
wire of the SWA cable as the Earth protective conductor?..

So now this becomes;


Red = Permanent live

Yellow = Switched live

Blue = Neutral

SWA wires = Earth



And of course label it all to denote that one is switched and the other
is live etc?..

Cheers..
--
Tony Sayer




__________ Information from ESET NOD32 Antivirus, version of virus
signature database 4180 (20090623) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com





__________ Information from ESET NOD32 Antivirus, version of virus signature database 4180 (20090623) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com

In article , Ian_m
scribeth thus
When I tried to do this at a mates house, provide unswitched live on the
yellow conductor I found the yellow was bonded to the SWA armour somewhere,
possibly an undergorund junction box so was not possible to do.

No this is fine, its all above ground well the jointed are..

--
Tony Sayer

In article , tony sayer
scribeth thus
In article , Ian_m
scribeth thus
When I tried to do this at a mates house, provide unswitched live on the
yellow conductor I found the yellow was bonded to the SWA armour somewhere,
possibly an undergorund junction box so was not possible to do.

No this is fine, its all above ground well the jointed are..


Further to this shenanigans we went to site yesterday and discovered
that Three of the SWA connections weren't that well connected, one was
totally disconnected the Steel having rusted away completely. What it
seems had happened is that they terminate in plastic boxes on the
underside of those and over time water has seeped into the top of where
the plastic cover goes and thence into the clamped part of the joint.

In fact one was full of water, and all were corroded quite badly for
about a foot or so .

However we came across un-rusted metal and made the connections. However
it looks that despite the sealing the same will happen again. It would
be more sensible to have the cables coming in the sides where the rain
will run off quicker, but that isn't practical. Anyone got any ideas in
how to prevent this perhaps filling them all with silicone sealant or
similar?..


cheers...
--
Tony Sayer

"tony sayer" wrote in message
...
In article , tony sayer
scribeth thus
In article , Ian_m
scribeth thus
When I tried to do this at a mates house, provide unswitched live on the
yellow conductor I found the yellow was bonded to the SWA armour
somewhere,
possibly an undergorund junction box so was not possible to do.

No this is fine, its all above ground well the jointed are..


Further to this shenanigans we went to site yesterday and discovered
that Three of the SWA connections weren't that well connected, one was
totally disconnected the Steel having rusted away completely. What it
seems had happened is that they terminate in plastic boxes on the
underside of those and over time water has seeped into the top of where
the plastic cover goes and thence into the clamped part of the joint.

In fact one was full of water, and all were corroded quite badly for
about a foot or so .

However we came across un-rusted metal and made the connections. However
it looks that despite the sealing the same will happen again. It would
be more sensible to have the cables coming in the sides where the rain
will run off quicker, but that isn't practical. Anyone got any ideas in
how to prevent this perhaps filling them all with silicone sealant or
similar?..


cheers...
--
Tony Sayer



The plastic box I have just used has a small drain hole at the bottom.

Lawrence

Further to this shenanigans we went to site yesterday and discovered
that Three of the SWA connections weren't that well connected, one was
totally disconnected the Steel having rusted away completely. What it
seems had happened is that they terminate in plastic boxes on the
underside of those and over time water has seeped into the top of where
the plastic cover goes and thence into the clamped part of the joint.

In fact one was full of water, and all were corroded quite badly for
about a foot or so .

However we came across un-rusted metal and made the connections. However
it looks that despite the sealing the same will happen again. It would
be more sensible to have the cables coming in the sides where the rain
will run off quicker, but that isn't practical. Anyone got any ideas in
how to prevent this perhaps filling them all with silicone sealant or
similar?..


The plastic box I have just used has a small drain hole at the bottom.

Lawrence


There isn't a problem with water -in- the box, its where it drains down
the outside and then goes under the box and seemingly makes its way into
the bit between the bottom of the box and the top of the sealing of the
gland cover...

BTW thanks to the gent recommending Magi Gel I did reply but it bounced
back;!..
--
Tony Sayer