Hi peeps,

I am wiring in an intercom system from my gate intercom to the house. It is
a video intercom and uses non screened twisted cables. The manufacturer
recommends this-
http://uk.rs-online.com/web/p/produc...FdOhtAod_iUA7Q
Which, for the 100m i need, is quite expensive. I was wondering if i could
use flat 1.5mm twin and just twist it a fair bit?

Whaddya recon?

Ta

Steve

In article , Mr
Sandman writes

Which, for the 100m i need, is quite expensive.

you're not joking!

I was wondering if i could
use flat 1.5mm twin and just twist it a fair bit?

Cat5 network cable will be fine and is dirt cheap. You'll only use one
pair out of the four, but it doesn't matter.

--
(\_/)
(='.'=)
(")_(")

"Mr Sandman" wrote in message
o.uk...
Hi peeps,

I am wiring in an intercom system from my gate intercom to the house. It
is a video intercom and uses non screened twisted cables. The
manufacturer recommends this-
http://uk.rs-online.com/web/p/produc...FdOhtAod_iUA7Q

Which, for the 100m i need, is quite expensive. I was wondering if i
could use flat 1.5mm twin

Bet you can.

and just twist it a fair bit?

Wont make any difference, you need to twist it before it's a twin.

Whaddya recon?

Should be fine and doesn't cost much to try.

On Wed, 25 Jun 2014 12:06:05 +0100, "Mr Sandman"
wrote:

Hi peeps,

I am wiring in an intercom system from my gate intercom to the house. It is
a video intercom and uses non screened twisted cables. The manufacturer
recommends this-
http://uk.rs-online.com/web/p/produc...FdOhtAod_iUA7Q
Which, for the 100m i need, is quite expensive. I was wondering if i could
use flat 1.5mm twin and just twist it a fair bit?

Whaddya recon?

Ta

Steve


100M of CAT5 is about £20.

--

Graham.

%Profound_observation%

cat 5 e is not thick enough for the distance, they recommend at least
1mm2...

"Mike Tomlinson" wrote in message ...

In article , Mr
Sandman writes

Which, for the 100m i need, is quite expensive.

you're not joking!

I was wondering if i could
use flat 1.5mm twin and just twist it a fair bit?

Cat5 network cable will be fine and is dirt cheap. You'll only use one
pair out of the four, but it doesn't matter.

--
(\_/)
(='.'=)
(")_(")

In article ,
Mike Tomlinson wrote:
In article , Mr
Sandman writes

Which, for the 100m i need, is quite expensive.

you're not joking!

I was wondering if i could
use flat 1.5mm twin and just twist it a fair bit?

Cat5 network cable will be fine and is dirt cheap. You'll only use one
pair out of the four, but it doesn't matter.

The cable shown is 16 AWG or approx 1.3mm² - so may be carrying a fair bit
of DC to power the remote.

--
*24 hours in a day ... 24 beers in a case ... coincidence? *

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

On Wed, 25 Jun 2014 13:07:45 +0100, "Mr Sandman"
wrote:

cat 5 e is not thick enough for the distance, they recommend at least
1mm2...


You need to tell us more about the intercom. It could be that the pair
is being used to power the thing as well as carry low level audio.

--

Graham.

%Profound_observation%

"Mr Sandman" wrote in message
o.uk...

Hi peeps,

I am wiring in an intercom system from my gate intercom to the house. It
is a video intercom and uses non screened twisted cables. The manufacturer
recommends this-
http://uk.rs-online.com/web/p/produc...FdOhtAod_iUA7Q
Which, for the 100m i need, is quite expensive. I was wondering if i could
use flat 1.5mm twin and just twist it a fair bit?

Whaddya recon?

Ta

Steve

This any good?

http://www.ebay.co.uk/itm/SCREENED-T...item5afebb23ef

or if it's in ducting / cnduit, buy a couple of 100 m rolls of 1.5 mm
conduit cable and twist them with a drill.

Andrew

In article , Dave Plowman (News)
writes

The cable shown is 16 AWG or approx 1.3mm² - so may be carrying a fair bit
of DC to power the remote.

Double (or more) the pairs up, then, e.g. use both blue and blue/white
wires for +ve and both green and green/white wires for -ve.

Still leaves you with two spare pairs.

--
(\_/)
(='.'=)
(")_(")

In article , Andrew Mawson andrew@please_re
move_me.mawson.org.uk writes

http://www.ebay.co.uk/itm/SCREENED-T...r-CBBR6385-/39
0820733935?pt=UK_BOI_Electrical_Components_Suppli es_ET&hash=item5afebb23ef

at 1.91 per m, it's gonna cost £191 for the 100m the OP wants?

--
(\_/)
(='.'=)
(")_(")

On Wednesday, June 25, 2014 12:06:05 PM UTC+1, Mr Sandman wrote:

Hi peeps,
I am wiring in an intercom system from my gate intercom to the house. It is
a video intercom and uses non screened twisted cables. The manufacturer
recommends this-
http://uk.rs-online.com/web/p/produc...FdOhtAod_iUA7Q
Which, for the 100m i need, is quite expensive. I was wondering if i could
use flat 1.5mm twin and just twist it a fair bit?
Whaddya recon?
Ta
Steve

Yep. Or use singles and a drill. Twist then tug a bit to set it.


NT

On 25/06/2014 12:06, Mr Sandman wrote:
Hi peeps,

I am wiring in an intercom system from my gate intercom to the house.
It is a video intercom and uses non screened twisted cables. The
manufacturer recommends this-
http://uk.rs-online.com/web/p/produc...FdOhtAod_iUA7Q

Which, for the 100m i need, is quite expensive. I was wondering if i
could use flat 1.5mm twin and just twist it a fair bit?

Whaddya recon?

Ta

Steve
It's speaker cable - http://www.belden.com/techdatas/metric/8471.pdf.

Look for a Belden 8471 equivalent. A quick search brings up these
(neither of which I've heard of so I can't vouch for them).

http://www.quadtronics.co.uk/8471-eq...00m-2025-p.asp

http://www.electricwholesale.co.uk/b...471-lsf-cable/

Unless you really need the LSZH bit it's a lot cheaper.

You need to look at the electrical requirements to see if Cat 5 (as
suggested by others) would do. Its DC resistance is much higher.

wrote in message
...
On Wednesday, June 25, 2014 12:06:05 PM UTC+1, Mr Sandman wrote:

Hi peeps,
I am wiring in an intercom system from my gate intercom to the house. It
is
a video intercom and uses non screened twisted cables. The manufacturer
recommends this-
http://uk.rs-online.com/web/p/produc...FdOhtAod_iUA7Q
Which, for the 100m i need, is quite expensive. I was wondering if i
could
use flat 1.5mm twin and just twist it a fair bit?
Whaddya recon?
Ta
Steve

Yep. Or use singles and a drill. Twist then tug a bit to set it.

But don't do it too much, or you'll go blind

In article ,
writes:
On Wednesday, June 25, 2014 12:06:05 PM UTC+1, Mr Sandman wrote:
Hi peeps,
I am wiring in an intercom system from my gate intercom to the house. It is
a video intercom and uses non screened twisted cables. The manufacturer
recommends this-
http://uk.rs-online.com/web/p/produc...FdOhtAod_iUA7Q
Which, for the 100m i need, is quite expensive. I was wondering if i could
use flat 1.5mm twin and just twist it a fair bit?
Whaddya recon?
Ta
Steve
Yep. Or use singles and a drill. Twist then tug a bit to set it.

I have done this in the past.

For a suspended wire, you might also want to twist in a catenary wire,
to provide enough tensile strength to carry the weight and wind forces
over a long span.

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

"Graham." wrote in message
...

On Wed, 25 Jun 2014 13:07:45 +0100, "Mr Sandman"
wrote:

cat 5 e is not thick enough for the distance, they recommend at least
1mm2...


You need to tell us more about the intercom. It could be that the pair
is being used to power the thing as well as carry low level audio.

--

Graham.

%Profound_observation%

Here you go, yes it does carry the power to the remote video unit, but i
expect the high mm2 is for video quality rather than high current load.

http://www.onlinesecurityproducts.co...cdv2796kp.html

Steve

"Mike Tomlinson" wrote in message
...
In article , Dave Plowman (News)
writes

The cable shown is 16 AWG or approx 1.3mm² - so may be carrying a fair bit
of DC to power the remote.

Double (or more) the pairs up, then, e.g. use both blue and blue/white
wires for +ve and both green and green/white wires for -ve.

Still leaves you with two spare pairs.


You would be better off doubling up by using the blue and green as +ve and
the blue/white and green/white as -ve.

--
Adam

On Wednesday, June 25, 2014 12:06:05 PM UTC+1, Mr Sandman wrote:
I am wiring in an intercom system from my gate intercom to the house. It is
a video intercom and uses non screened twisted cables.

I would try a loudspeaker cable such as
http://www.canford.co.uk/GPS-GENERAL...DSPEAKER-CABLE

cores are twisted on a 100 mm lay. £72 + VAT per 100 metres for the 1.5mm 2 core.

1mm is okay for 80 metres from gate panel to PSU or PSU to furthest monitor
http://doc.avaccesscontrol.co.uk/cdv...eDistances.pdf
http://www.farfisasecurity.co.uk/ind...product_id=623

Power consumption by the gate units is
DC 24V (supplied by PS1-24V or PS5-24V) Working status 200mA
Lock Power supply: 12Vdc, 300mA(Internal Power)

Owain

On Wed, 25 Jun 2014 18:28:00 +0100, ARW wrote:

The cable shown is 16 AWG or approx 1.3mm² - so may be carrying a
fair
bit of DC to power the remote.

Double (or more) the pairs up, then, e.g. use both blue and
blue/white
wires for +ve and both green and green/white wires for -ve.

You would be better off doubling up by using the blue and green as +ve
and the blue/white and green/white as -ve.

Why?

--
Cheers
Dave.

On Wednesday, June 25, 2014 6:30:45 PM UTC+1, wrote:
On Wednesday, June 25, 2014 12:06:05 PM UTC+1, Mr Sandman wrote:

I am wiring in an intercom system from my gate intercom to the house. It is
a video intercom and uses non screened twisted cables.
I would try a loudspeaker cable such as
http://www.canford.co.uk/GPS-GENERAL...DSPEAKER-CABLE
cores are twisted on a 100 mm lay. £72 + VAT per 100 metres for the 1.5mm 2 core.

Bell wire's 1/10th the price. Vdrop is 44mV/A/m for 1mm2 for pvc, so 0.22v/A/m for 0.2mm2 or 66mV/m at 0.3A - 6.6v @ 100m 0.3A. If I designed the intercom I'd make it work with that drop, but if they ask for 1.5mm it probably won't.


NT

1mm is okay for 80 metres from gate panel to PSU or PSU to furthest monitor
http://doc.avaccesscontrol.co.uk/cdv...eDistances.pdf
http://www.farfisasecurity.co.uk/ind...product_id=623
Power consumption by the gate units is
DC 24V (supplied by PS1-24V or PS5-24V) Working status 200mA
Lock Power supply: 12Vdc, 300mA(Internal Power)
Owain

"Dave Liquorice" wrote in message
ll.co.uk...
On Wed, 25 Jun 2014 18:28:00 +0100, ARW wrote:

The cable shown is 16 AWG or approx 1.3mm² - so may be carrying a
fair
bit of DC to power the remote.

Double (or more) the pairs up, then, e.g. use both blue and
blue/white
wires for +ve and both green and green/white wires for -ve.

You would be better off doubling up by using the blue and green as +ve
and the blue/white and green/white as -ve.

Why?

To make use of the twisted pair.



--
Adam

On Wed, 25 Jun 2014 20:41:41 +0100, ARW wrote:

Double (or more) the pairs up, then, e.g. use both blue and
blue/white wires for +ve and both green and green/white wires for
-ve.

You would be better off doubling up by using the blue and green as
+ve
and the blue/white and green/white as -ve.

Why?

To make use of the twisted pair.

eh? The pairs are colour/colourwhite not colour/colour or
colourwhite/colourwhite.

--
Cheers
Dave.

En el artículo o.uk,
Dave Liquorice escribió:

Why?

So that the twists in the cable are maintained for each wire. The
twists help to cancel out interference.

--
(\_/)
(='.'=)
(")_(")

And if he really wants a project, I've done it with a piece of single core
pvc wire, about 2.5 times the run, One end tied to a door handle the other
walked down the garden till its taught, and then wind for the twists to
suit.
Brian

--
From the Sofa of Brian Gaff Reply address is active
"Mike Tomlinson" wrote in message
...
In article , Mr
Sandman writes

Which, for the 100m i need, is quite expensive.

you're not joking!

I was wondering if i could
use flat 1.5mm twin and just twist it a fair bit?

Cat5 network cable will be fine and is dirt cheap. You'll only use one
pair out of the four, but it doesn't matter.

--
(\_/)
(='.'=)
(")_(")

On 25/06/2014 15:25, Andy wrote:
On 25/06/2014 12:06, Mr Sandman wrote:
Hi peeps,

I am wiring in an intercom system from my gate intercom to the house.
It is a video intercom and uses non screened twisted cables. The
manufacturer recommends this-
http://uk.rs-online.com/web/p/produc...FdOhtAod_iUA7Q


Which, for the 100m i need, is quite expensive. I was wondering if i
could use flat 1.5mm twin and just twist it a fair bit?

Whaddya recon?

Ta

Steve
It's speaker cable - http://www.belden.com/techdatas/metric/8471.pdf.

Look for a Belden 8471 equivalent. A quick search brings up these
(neither of which I've heard of so I can't vouch for them).

http://www.quadtronics.co.uk/8471-eq...00m-2025-p.asp

http://www.electricwholesale.co.uk/b...471-lsf-cable/

Unless you really need the LSZH bit it's a lot cheaper.


For info, LSZH is Low Smoke Zero Halogen.... basically its a special
polymer that when set on fire does not release much smoke and zero
halogenated compounds.

On 25/06/2014 21:08, Mike Tomlinson wrote:
En el artículo o.uk,
Dave Liquorice escribió:

Why?

So that the twists in the cable are maintained for each wire. The
twists help to cancel out interference.



I believe from my electronic days this is referred to as CMRR Common
Mode Rejection Ratio.

Its also used in Ethernet cabling, you will see four twisted pairs in
there too,

On 25/06/2014 21:11, Brian Gaff wrote:
And if he really wants a project, I've done it with a piece of single core
pvc wire, about 2.5 times the run, One end tied to a door handle the other
walked down the garden till its taught, and then wind for the twists to
suit.

Using an electric drill to twist the cable.?


--
mailto:news{at}admac(dot}myzen{dot}co{dot}uk

On 25/06/2014 23:19, alan wrote:
On 25/06/2014 21:11, Brian Gaff wrote:
And if he really wants a project, I've done it with a piece of single
core
pvc wire, about 2.5 times the run, One end tied to a door handle the
other
walked down the garden till its taught, and then wind for the twists to
suit.

Using an electric drill to twist the cable.?


I'd use a hand drill myself.

--
Tciao for Now!

John.

En el artículo , alan
escribió:

Using an electric drill to twist the cable.?

'tis how I do it (using a battery drill on its slowest speed).

Also need to bear in mind that a 100m length of wire won't be 100m by
the time you've twisted it, it'll be roughly a third shorter depending
on how may twists have been applied.

--
(\_/)
(='.'=)
(")_(")

"Mike Tomlinson" wrote in message ...

En el artículo , alan
escribió:

Using an electric drill to twist the cable.?

'tis how I do it (using a battery drill on its slowest speed).

Also need to bear in mind that a 100m length of wire won't be 100m by
the time you've twisted it, it'll be roughly a third shorter depending
on how may twists have been applied.

--
good point! I think i will have a shot at it. Will see what i can find
cheapish and use an electric drill to twist.

How about this -
http://www.screwfix.com/p/philex-spe...0m-white/87199

Steve

"Mr Sandman" wrote in message
o.uk...



"Mike Tomlinson" wrote in message ...

En el artículo , alan
escribió:

Using an electric drill to twist the cable.?

'tis how I do it (using a battery drill on its slowest speed).

Also need to bear in mind that a 100m length of wire won't be 100m by
the time you've twisted it, it'll be roughly a third shorter depending
on how may twists have been applied.

--
good point! I think i will have a shot at it. Will see what i can find
cheapish and use an electric drill to twist.

How about this -
http://www.screwfix.com/p/philex-spe...0m-white/87199

Steve

or this -
http://www.screwfix.com/p/conduit-wi...00m-blue/34152

What is better for twisting, solid core or stranded?

Steve

On Wed, 25 Jun 2014 21:08:55 +0100, Mike Tomlinson wrote:

Why?

So that the twists in the cable are maintained for each wire.

But if you take colour and colour there are no twists(*) as you
have picked a single wire from two pairs.

The twists help to cancel out interference.

There could be an argument that spliting the supply across two pairs
means that each pair has supply "noise" and "anti-noise" so will tend
to cancel out and not radiate. But that only works if the DC supply
is being fed from a balanced source, ie both legs floating, most DC
supplies have one leg tied to ground/chassis. It's also making the
assumption that the "noise" is the same in both legs, with a bit of
active kit sucking power I doubt that will be the case, even if you
sorted out a balanced feed.

I'm sure those that designed PoE and used both wires of one pair for
+V and both wires of another pair for -V knew what they were doing.
B-)

(*) There might be a very long twist due to the lay of the pairs in
the cable but being long won't be very effective and each wire would
not be closely twisted with its twin.

--
Cheers
Dave.

On Thursday, June 26, 2014 3:40:21 AM UTC+1, Mike Tomlinson wrote:
En el art�culo , alan
escribi�:

Using an electric drill to twist the cable.?
'tis how I do it (using a battery drill on its slowest speed).
Also need to bear in mind that a 100m length of wire won't be 100m by
the time you've twisted it, it'll be roughly a third shorter depending
on how may twists have been applied.

You'd have to do an awful lot of twisting to lose 1/3 the length. Twist till 10% down should be plenty.


NT

If cost is critical, TLC do twin 1.5mm flex for 40 quid 100 metres.

--
*If all is not lost, where the hell is it?

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

On 26/06/2014 09:08, Dave Liquorice wrote:


I'm sure those that designed PoE and used both wires of one pair for
+V and both wires of another pair for -V knew what they were doing.
B-)

Its nothing to do with noise though.
The pairs can still be used for signals while having power on them.
The power induced noise on the pair will be cancelled out by the twisting.

On Thu, 26 Jun 2014 13:25:55 +0100, Dennis@home wrote:

I'm sure those that designed PoE and used both wires of one pair
for
+V and both wires of another pair for -V knew what they were
doing.
B-)

Its nothing to do with noise though.

But DC won't be a problem (apart from on off) no matter what wires
you use. Only AC can couple from one conductor to another.

The pairs can still be used for signals while having power on them.

This is true, use it all the time in the day job. "Ordinary" PoE uses
the two spare pairs in Cat5 to carry +V on one pair and -V on the
other.

The power induced noise on the pair will be cancelled out by the
twisting.

Ish. The twists are there to try and ensure that any induced noise is
identical in each wire of the pair. The receiver is looking for a
difference between the wires for a signal. Noise induced equally in
both wires (common mode) doesn't produce a difference so isn't "seen"
by the reciever.

Anyway this isn't sorting out why Adam suggested colour/colour
and colourwhite/colourwhite for supply and return.

If the two pairs formed a star quad it would be important to select
the corect wires. I can't see how spliting the power across two
pairs, one wire from each pair per leg, carries any advantage.

--
Cheers
Dave.

wrote in message
...
On Wednesday, June 25, 2014 6:30:45 PM UTC+1,
wrote:
On Wednesday, June 25, 2014 12:06:05 PM UTC+1, Mr Sandman wrote:

I am wiring in an intercom system from my gate intercom to the house.
It is
a video intercom and uses non screened twisted cables.
I would try a loudspeaker cable such as
http://www.canford.co.uk/GPS-GENERAL...DSPEAKER-CABLE
cores are twisted on a 100 mm lay. £72 + VAT per 100 metres for the 1.5mm
2 core.

Bell wire's 1/10th the price. Vdrop is 44mV/A/m for 1mm2 for pvc, so
0.22v/A/m for 0.2mm2 or 66mV/m at 0.3A - 6.6v @ 100m 0.3A. If I designed
the intercom I'd make it work with that drop, but if they ask for 1.5mm it
probably won't.


NT

1mm is okay for 80 metres from gate panel to PSU or PSU to furthest
monitor
http://doc.avaccesscontrol.co.uk/cdv...eDistances.pdf
http://www.farfisasecurity.co.uk/ind...product_id=623
Power consumption by the gate units is
DC 24V (supplied by PS1-24V or PS5-24V) Working status 200mA
Lock Power supply: 12Vdc, 300mA(Internal Power)
Owain

couldn't you just install the conduit for the wires, then leave it empty,
fit a trumpet bell on each end and use it like the old voice tubes on ships?

On 26/06/2014 16:29, Dave Liquorice wrote:
On Thu, 26 Jun 2014 13:25:55 +0100, Dennis@home wrote:

I'm sure those that designed PoE and used both wires of one pair
for
+V and both wires of another pair for -V knew what they were
doing.
B-)

Its nothing to do with noise though.

But DC won't be a problem (apart from on off) no matter what wires
you use. Only AC can couple from one conductor to another.

The pairs can still be used for signals while having power on them.

This is true, use it all the time in the day job. "Ordinary" PoE uses
the two spare pairs in Cat5 to carry +V on one pair and -V on the
other.

It doesn't use spare pairs as PoE works with gigE and that usually uses
all the pairs.


The power induced noise on the pair will be cancelled out by the
twisting.

Ish. The twists are there to try and ensure that any induced noise is
identical in each wire of the pair. The receiver is looking for a
difference between the wires for a signal. Noise induced equally in
both wires (common mode) doesn't produce a difference so isn't "seen"
by the reciever.

Anyway this isn't sorting out why Adam suggested colour/colour
and colourwhite/colourwhite for supply and return.

If the two pairs formed a star quad it would be important to select
the corect wires. I can't see how spliting the power across two
pairs, one wire from each pair per leg, carries any advantage.


Well with ethernet the two legs of a pair are connected together at each
end by some copper wire, the winding in the pulse transformers.

Shoving a power supply across them is going to produce smoke at one or
both ends if its plugged into a gigE switch.

I suspect adam doesn't know the pairs are looped when plugged in, or
does know and he is being mischeveous.

"Dennis@home" wrote in message
eb.com...
On 26/06/2014 16:29, Dave Liquorice wrote:
On Thu, 26 Jun 2014 13:25:55 +0100, Dennis@home wrote:

I'm sure those that designed PoE and used both wires of one pair
for
+V and both wires of another pair for -V knew what they were
doing.
B-)

Its nothing to do with noise though.

But DC won't be a problem (apart from on off) no matter what wires
you use. Only AC can couple from one conductor to another.

The pairs can still be used for signals while having power on them.

This is true, use it all the time in the day job. "Ordinary" PoE uses
the two spare pairs in Cat5 to carry +V on one pair and -V on the
other.

It doesn't use spare pairs as PoE works with gigE and that usually uses
all the pairs.


The power induced noise on the pair will be cancelled out by the
twisting.

Ish. The twists are there to try and ensure that any induced noise is
identical in each wire of the pair. The receiver is looking for a
difference between the wires for a signal. Noise induced equally in
both wires (common mode) doesn't produce a difference so isn't "seen"
by the reciever.

Anyway this isn't sorting out why Adam suggested colour/colour
and colourwhite/colourwhite for supply and return.

If the two pairs formed a star quad it would be important to select
the corect wires. I can't see how spliting the power across two
pairs, one wire from each pair per leg, carries any advantage.


Well with ethernet the two legs of a pair are connected together at each
end by some copper wire, the winding in the pulse transformers.

Shoving a power supply across them is going to produce smoke at one or
both ends if its plugged into a gigE switch.

I suspect adam doesn't know the pairs are looped when plugged in, or does
know and he is being mischeveous.



Plugged in? I never suggested plugging anything in.

--
Adam

On Thu, 26 Jun 2014 19:24:19 +0100, Dennis@home wrote:

This is true, use it all the time in the day job. "Ordinary" PoE
uses
the two spare pairs in Cat5 to carry +V on one pair and -V on the
other.

It doesn't use spare pairs as PoE works with gigE and that usually uses
all the pairs.

That's why I said "ordinary". B-)

If the two pairs formed a star quad it would be important to
select
the corect wires. I can't see how spliting the power across two
pairs, one wire from each pair per leg, carries any advantage.

Well with ethernet the two legs of a pair are connected together at each
end by some copper wire, the winding in the pulse transformers.

Only on the ones carrying data, the "spare" pairs 10 or 100 Mbps are
open circuit. Gigabit is different as that does use all 4 pairs.

Shoving a power supply across them is going to produce smoke at one or
both ends if its plugged into a gigE switch.

I suspect adam doesn't know the pairs are looped when plugged in, or
does know and he is being mischeveous.

And is also talking about this intercom application. TBH I can't see
why and intercom would want to draw 200 mA @ 24 V (4.8 W) the lock
release is local. Hum, maybe that 200 mA is trickle charge for the
lock release battery? Thus not that fussy about volts/current. I
wonder what the electronics actually live off?

--
Cheers
Dave.

"Dave Liquorice" wrote in message
ll.co.uk...
On Wed, 25 Jun 2014 20:41:41 +0100, ARW wrote:

Double (or more) the pairs up, then, e.g. use both blue and
blue/white wires for +ve and both green and green/white wires for
-ve.

You would be better off doubling up by using the blue and green as
+ve
and the blue/white and green/white as -ve.

Why?

To make use of the twisted pair.

eh? The pairs are colour/colourwhite not colour/colour or
colourwhite/colourwhite.


It's the way you are taught to install CCTV. One pair for the video signal
and the other pairs for the power. It is supposed to improve the signal.

--
Adam