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  #1   Report Post  
Andy Hall
 
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Default Cable colours for 110v fixed wiring


For convenience of use in the workshop I've added wiring and EN 60309
yellow industrial outlets carrying 110v from a centre tapped site
transformer switched on when power is required.

There is a male wall mounted connector near the CU to pick up the
outlet from the transformer and the wiring from that runs through the
third compartment of the three compartment trunking to a few outlets
around the walls. This trunking section is segregated and dedicated
to the 110v wiring which is wired in PVC singles.

I need to add some more outlets and am doing some additional 230v
wiring as well and while looking at some other issues looked at the
identification section 514 of BS7671

I had done the original wiring using red and black for the two 55v
cables and green/yellow for the centre tapped earth on the argument of
it being a single phase circuit.

However, having thought about it, I rather wonder since one could
argue that the two 55v cables are equivalent with neither being at or
close to ground potential. There does not seem to be an official
colour identification spec. in BS7671 (even in the new colours) to
cover this case.

It doesn't seem right to run it with two reds either, although I
suppose one could argue that a red and a yellow as being two "phases"
would be legitimate. Equally, it could be reasonably argued that
two yellows be used, especially since they would be 6mm^2 and quite
obvious as well as segregated on the basis that yellow is associated
with the 110v transformer and outlets.

I can't see anything that clearly covers this scenario of a split low
voltage single phase a.c. circuit.

Thoughts?


..andy

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  #2   Report Post  
Andrew Gabriel
 
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Default Cable colours for 110v fixed wiring

In article ,
Andy Hall writes:

For convenience of use in the workshop I've added wiring and EN 60309
yellow industrial outlets carrying 110v from a centre tapped site
transformer switched on when power is required.


It doesn't seem right to run it with two reds either, although I


I've seen it done (once) in two browns, which was a mixure of singles
in conduit and T&E. This was before that would become the new colour
replacing two reds of course. (These colour T&E have been in use in
the Irish Republic for some years, so they probably have been available
with some difficulty for long time.) Given the new colours, I would be
tempted to go for two yellows now if it's all singles and you aren't
using yellow for anything else.

AFAIR, the yellow Arctic flex uses the standard brown/blue/green/yellow.

suppose one could argue that a red and a yellow as being two "phases"
would be legitimate. Equally, it could be reasonably argued that
two yellows be used, especially since they would be 6mm^2 and quite
obvious as well as segregated on the basis that yellow is associated
with the 110v transformer and outlets.


I guess you remembered to allow for 4 times the power loss due to
voltage drop.

--
Andrew Gabriel
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Mike Tomlinson
 
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Default Cable colours for 110v fixed wiring

In article , Andy Hall
writes

Thoughts?


My first reaction is that, although you have the 110v and 230v cables
segregated in your trunking, it would be sensible to choose different
colours for different voltages, purely as an identification aid in case
you have a 'senior moment'.

How about running the 110v cct in the American wiring colours - black
for live/hot, white for neutral, green/yellow for earth? If you look at
the flex wiring for 110v power tools, those are the colours used.

--
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  #4   Report Post  
Andy Hall
 
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Default Cable colours for 110v fixed wiring

On 26 Jun 2004 08:51:48 GMT, (Andrew
Gabriel) wrote:

In article ,
Andy Hall writes:

For convenience of use in the workshop I've added wiring and EN 60309
yellow industrial outlets carrying 110v from a centre tapped site
transformer switched on when power is required.


It doesn't seem right to run it with two reds either, although I


I've seen it done (once) in two browns, which was a mixure of singles
in conduit and T&E. This was before that would become the new colour
replacing two reds of course. (These colour T&E have been in use in
the Irish Republic for some years, so they probably have been available
with some difficulty for long time.) Given the new colours, I would be
tempted to go for two yellows now if it's all singles and you aren't
using yellow for anything else.


It is all singles.

Table 51A in the blue book only lists yellow as used for the Y phase
of a three phase circuit, although of course it is also commonly used
as one of the lives in two way lighting. I've used 1mm^2 yellow in
the centre compartment of the trunking for that purpose.

Interestingly, table 51 in Amendment 2 allows yellow as a control
circuit colour.

Given that the 110v wiring is running in another compartment and is in
6mm^2, it is pretty obvious and yellow does seem reasonable and not
missing from existing Table 51A.



AFAIR, the yellow Arctic flex uses the standard brown/blue/green/yellow.


Yes it does. I looked at some in an extension.



suppose one could argue that a red and a yellow as being two "phases"
would be legitimate. Equally, it could be reasonably argued that
two yellows be used, especially since they would be 6mm^2 and quite
obvious as well as segregated on the basis that yellow is associated
with the 110v transformer and outlets.


I guess you remembered to allow for 4 times the power loss due to
voltage drop.


Oh, yes. Hence the 6mm^2. The lengths are relatively short.

..andy

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  #5   Report Post  
Andy Hall
 
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Default Cable colours for 110v fixed wiring

On Sat, 26 Jun 2004 10:20:38 +0100, Mike Tomlinson
wrote:

In article , Andy Hall
writes

Thoughts?


My first reaction is that, although you have the 110v and 230v cables
segregated in your trunking, it would be sensible to choose different
colours for different voltages, purely as an identification aid in case
you have a 'senior moment'.


I did debate that, although on pulling off the trunking lids it does
become obvious because the wiring from the edge compartment drops only
into the EN60309 sockets and nowhere else.



How about running the 110v cct in the American wiring colours - black
for live/hot, white for neutral, green/yellow for earth? If you look at
the flex wiring for 110v power tools, those are the colours used.


I considered that as well, except that American ground connection is
green and not green/yellow, and there is potential confusion over
black in the new wiring colours anyway.

Added to this, I already have 6mm^2 black and red in the main section
of the trunking to carry single phase 230v radial circuits for the
machine outlets.

..andy

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  #6   Report Post  
N. Thornton
 
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Default Cable colours for 110v fixed wiring

Andy Hall wrote in message . ..
For convenience of use in the workshop I've added wiring and EN 60309
yellow industrial outlets carrying 110v from a centre tapped site
transformer switched on when power is required.

There is a male wall mounted connector near the CU to pick up the
outlet from the transformer and the wiring from that runs through the
third compartment of the three compartment trunking to a few outlets
around the walls. This trunking section is segregated and dedicated
to the 110v wiring which is wired in PVC singles.

I need to add some more outlets and am doing some additional 230v
wiring as well and while looking at some other issues looked at the
identification section 514 of BS7671

I had done the original wiring using red and black for the two 55v
cables and green/yellow for the centre tapped earth on the argument of
it being a single phase circuit.

However, having thought about it, I rather wonder since one could
argue that the two 55v cables are equivalent with neither being at or
close to ground potential. There does not seem to be an official
colour identification spec. in BS7671 (even in the new colours) to
cover this case.

It doesn't seem right to run it with two reds either, although I
suppose one could argue that a red and a yellow as being two "phases"
would be legitimate. Equally, it could be reasonably argued that
two yellows be used, especially since they would be 6mm^2 and quite
obvious as well as segregated on the basis that yellow is associated
with the 110v transformer and outlets.

I can't see anything that clearly covers this scenario of a split low
voltage single phase a.c. circuit.

Thoughts?



If you use the same colours as something else, ie red or yellow/green,
mistakes are liable to occur in future. A purpose of colour selcetion
is to greatly reduce this chance. This is especially relevant with
yellow/green colour, which I certainly would not use for the 0v line,
any more than one would use it for 240v neutral.


Regards, NT
  #7   Report Post  
Dave Liquorice
 
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Default Cable colours for 110v fixed wiring

On Sat, 26 Jun 2004 10:35:06 +0100, Andy Hall wrote:

Given that the 110v wiring is running in another compartment and is
in 6mm^2, it is pretty obvious and yellow does seem reasonable ...


From the "common sense" stand point the supply is balanced so there is
not need to identify the phases (like there is in 3 phase) so the same
colour can be used for both. Both are at 55v above earth and yellow is
already associated with 110v "safe" supplies it therefore seems
logical to use two yellows.

The center tap, is that bonded to local earth or floating? If it is
bonded and thus a real protective earth then green/yellow would be
logical. If it's floating hum, well...

--
Cheers
Dave. pam is missing e-mail



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Owain
 
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Default Cable colours for 110v fixed wiring

"N. Thornton" wrote
| If you use the same colours as something else, ie red or yellow/green,
| mistakes are liable to occur in future. A purpose of colour selcetion
| is to greatly reduce this chance. This is especially relevant with
| yellow/green colour, which I certainly would not use for the 0v line,
| any more than one would use it for 240v neutral.

But in this setting the 55-0-55 centre tap is earth, it's analogous to using
red-yellow-blue and green/yellow on a three-phase supply with no neutral.

Owain


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Andy Hall
 
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Default Cable colours for 110v fixed wiring

On Sat, 26 Jun 2004 12:22:34 +0100 (BST), "Dave Liquorice"
wrote:

On Sat, 26 Jun 2004 10:35:06 +0100, Andy Hall wrote:

Given that the 110v wiring is running in another compartment and is
in 6mm^2, it is pretty obvious and yellow does seem reasonable ...


From the "common sense" stand point the supply is balanced so there is
not need to identify the phases (like there is in 3 phase) so the same
colour can be used for both. Both are at 55v above earth and yellow is
already associated with 110v "safe" supplies it therefore seems
logical to use two yellows.

The center tap, is that bonded to local earth or floating? If it is
bonded and thus a real protective earth then green/yellow would be
logical. If it's floating hum, well...


It is bonded to earth.

Like you say and Andrew had also suggested, large yellow cables seem
sensible. It isn't even as though phase identification is important
as it is with three phase. Nevertheless, I'll probably connect it
consistently.




..andy

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  #10   Report Post  
Dave Plowman (News)
 
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Default Cable colours for 110v fixed wiring

In article ,
Andy Hall wrote:
It doesn't seem right to run it with two reds either, although I
suppose one could argue that a red and a yellow as being two "phases"
would be legitimate. Equally, it could be reasonably argued that
two yellows be used, especially since they would be 6mm^2 and quite
obvious as well as segregated on the basis that yellow is associated
with the 110v transformer and outlets.


Absolutely no help, but I always use yellow for AC other than mains in
electronics. Suppose it's because I didn't want to double up on every
colour of equipment wire, and have that as one of my 24/0.2 reels.

--
*Generally speaking, you aren't learning much if your lips are moving.*

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


  #11   Report Post  
Dave Plowman (News)
 
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Default Cable colours for 110v fixed wiring

In article ,
Mike Tomlinson wrote:
How about running the 110v cct in the American wiring colours - black
for live/hot, white for neutral, green/yellow for earth? If you look at
the flex wiring for 110v power tools, those are the colours used.


I'd certainly *not* use black, given that it's already a designated colour.

--
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Dave Plowman London SW
To e-mail, change noise into sound.
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Mike Tomlinson
 
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Default Cable colours for 110v fixed wiring

In article , Dave Plowman (News)
writes

I'd certainly *not* use black, given that it's already a designated colour.


Andy did say that he has used segmented trunking. And if it were me
installing the wiring, I'd use cable ties to group cables together to
avoid confusion. Perhaps use grey instead of black?

--
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Q. What's the most annoying thing on Usenet?

  #13   Report Post  
Christian McArdle
 
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Default Cable colours for 110v fixed wiring

I can't see anything that clearly covers this scenario of a split low
voltage single phase a.c. circuit.


Personally, I'd use new colours. Blue for neutral (0V) and two phase colours
for the 55V, avoiding brown, purely to distinguish from standard 230V live.
I would not use green/yellow unless it was used as a protective conductor,
in which case green/yellow would be compulsory.

Christian.


  #14   Report Post  
Owain
 
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Default Cable colours for 110v fixed wiring

"Mike Tomlinson" wrote
| Andy did say that he has used segmented trunking. And if it
| were me installing the wiring, I'd use cable ties to group
| cables together to avoid confusion. Perhaps use grey instead
| of black?

Three-wire dc circuits are supposed to be L+ brown, Mid (possibly earthed)
Blue, and L- Grey, so brown and grey would be 'consistent'.

However "control circuits, ELV and other applications" phase colour can be
Brown, Black, Red, Orange, Yellow, Violet, Grey, White, Pink or Turqoise.
Neutral or Mid-wire is Blue. An earthed PELV conductor is blue.

(from Wiring Matters).

I think White is/was Telecomms Functional Earth, which might not be too
happy about being mistaken for 55 V ac.

Owain


  #15   Report Post  
Andy Hall
 
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Default Cable colours for 110v fixed wiring

On Sat, 26 Jun 2004 18:18:27 +0100, "Christian McArdle"
wrote:

I can't see anything that clearly covers this scenario of a split low
voltage single phase a.c. circuit.


Personally, I'd use new colours. Blue for neutral (0V) and two phase colours
for the 55V, avoiding brown, purely to distinguish from standard 230V live.
I would not use green/yellow unless it was used as a protective conductor,
in which case green/yellow would be compulsory.

Christian.


I did think about that, but then thought that really the 0v is not
really a neutral but more of a protective earth since it is connected
to the case of the tool if it is not double insulated and through to
earth at the transformer. It shouldn't be carrying current either
except under fault conditions.
Therefore I think that it should be green/yellow.

Then the question is for the two 55v lines
This really only leaves grey using the new colours because I would not
want to use black.




..andy

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  #16   Report Post  
G&M
 
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Default Cable colours for 110v fixed wiring


"Andy Hall" wrote in message
...

For convenience of use in the workshop I've added wiring and EN 60309
yellow industrial outlets carrying 110v from a centre tapped site
transformer switched on when power is required.

There is a male wall mounted connector near the CU to pick up the
outlet from the transformer and the wiring from that runs through the
third compartment of the three compartment trunking to a few outlets
around the walls. This trunking section is segregated and dedicated
to the 110v wiring which is wired in PVC singles.

I need to add some more outlets and am doing some additional 230v
wiring as well and while looking at some other issues looked at the
identification section 514 of BS7671

I had done the original wiring using red and black for the two 55v
cables and green/yellow for the centre tapped earth on the argument of
it being a single phase circuit.

However, having thought about it, I rather wonder since one could
argue that the two 55v cables are equivalent with neither being at or
close to ground potential. There does not seem to be an official
colour identification spec. in BS7671 (even in the new colours) to
cover this case.

It doesn't seem right to run it with two reds either, although I
suppose one could argue that a red and a yellow as being two "phases"
would be legitimate.



White is often used for both 110v wires in sound and lighting touring
equipment to identify it as NOT one fo the three 240v phases or directly
connected to it. Up to the 1970s white (line-ish) and black (neutral-ish)
were used.



  #17   Report Post  
Dave Plowman (News)
 
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Default Cable colours for 110v fixed wiring

In article ,
G&M wrote:
White is often used for both 110v wires in sound and lighting touring
equipment to identify it as NOT one fo the three 240v phases or directly
connected to it.


That certainly makes more sense than yellow, but of course might be much
more difficult to obtain.

Up to the 1970s white (line-ish) and black (neutral-ish)
were used.


If it's off an isolating transformer, there's no such thing.

--
*Acupuncture is a jab well done.*

Dave Plowman London SW
To e-mail, change noise into sound.
  #18   Report Post  
Andrew Gabriel
 
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Default Cable colours for 110v fixed wiring

In article ,
"G&M" writes:

White is often used for both 110v wires in sound and lighting touring
equipment to identify it as NOT one fo the three 240v phases or directly


Not to be confused with cream, which is a clean earth.

connected to it. Up to the 1970s white (line-ish) and black (neutral-ish)
were used.


Those are the US colours, except they're the wrong way round.

--
Andrew Gabriel
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N. Thornton
 
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Default Cable colours for 110v fixed wiring

"Owain" wrote in message ...
"N. Thornton" wrote
| If you use the same colours as something else, ie red or yellow/green,
| mistakes are liable to occur in future. A purpose of colour selcetion
| is to greatly reduce this chance. This is especially relevant with
| yellow/green colour, which I certainly would not use for the 0v line,
| any more than one would use it for 240v neutral.

But in this setting the 55-0-55 centre tap is earth, it's analogous to using
red-yellow-blue and green/yellow on a three-phase supply with no neutral.

Owain


I'm a bit unclear what the OP is doing with the 110v CT wiring. I
would have expected a power circuit to use N rather than E. 240v
neutral is earth too, but theres reason we dont use it for CPC earth.
The Americans do.

Without knowing quite what OP is doing with that CT...


Regards, NT
  #20   Report Post  
G&M
 
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Default Cable colours for 110v fixed wiring


"Dave Plowman (News)" wrote in message
...
In article ,
G&M wrote:
White is often used for both 110v wires in sound and lighting touring
equipment to identify it as NOT one fo the three 240v phases or directly
connected to it.


That certainly makes more sense than yellow, but of course might be much
more difficult to obtain.

Up to the 1970s white (line-ish) and black (neutral-ish)
were used.


If it's off an isolating transformer, there's no such thing.


Not quite. B****y valve amps without transformers were the problem.
Everything had to be carefully earthed to avoid ground buzz so convention
was the black one could be connected to the common earth if needed, the
white most definitely couldn't. Nowadays I think all such amps use
isolating transformers and in any case all live (as opposed to soon to be
dead) guitarists have protective cutouts on their leads.




  #21   Report Post  
Andy Hall
 
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Default Cable colours for 110v fixed wiring

On 26 Jun 2004 16:11:16 -0700, (N. Thornton) wrote:

"Owain" wrote in message ...
"N. Thornton" wrote
| If you use the same colours as something else, ie red or yellow/green,
| mistakes are liable to occur in future. A purpose of colour selcetion
| is to greatly reduce this chance. This is especially relevant with
| yellow/green colour, which I certainly would not use for the 0v line,
| any more than one would use it for 240v neutral.

But in this setting the 55-0-55 centre tap is earth, it's analogous to using
red-yellow-blue and green/yellow on a three-phase supply with no neutral.

Owain


I'm a bit unclear what the OP is doing with the 110v CT wiring.


It was in the original post. The circuit is to distribute 110v from
a site transformer to fixed outlets (EN60309 yellow type) to run power
tools in the workshop. This is because it is a PITA lugging the
transformer around and more convenient just to plug them into a wall
outlet.

The transformer is an isolating type and has a centre tapped secondary
giving 55-0-55v with the centre tap connected to ground.

Thus there are, in effect, two phase connections of 55v each (they are
balanced about earth) and the earth. Neither of the 55v
connections can be described as a neutral because it is 55v away from
earth. Equally, no current will flow through the centre tapped wire
unless there is a fault because it will be connected to the tool case
or not connected.

I
would have expected a power circuit to use N rather than E.


It's isolated and balanced.......


240v
neutral is earth too, but theres reason we dont use it for CPC earth.
The Americans do.

Without knowing quite what OP is doing with that CT...


Regards, NT


..andy

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  #22   Report Post  
Dave Plowman (News)
 
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Default Cable colours for 110v fixed wiring

In article ,
G&M wrote:
Up to the 1970s white (line-ish) and black (neutral-ish)
were used.


If it's off an isolating transformer, there's no such thing.


Not quite. B****y valve amps without transformers were the problem.
Everything had to be carefully earthed to avoid ground buzz so convention
was the black one could be connected to the common earth if needed, the
white most definitely couldn't.


I mean the circuit - as in Andy's case, is fed from an isolating
transformer, so there is no relation to earth - unless the centre tap is
earthed, etc.

I know what you mean about those bl***y awful AC/DC valve amps, though -
death traps.

Nowadays I think all such amps use
isolating transformers and in any case all live (as opposed to soon to be
dead) guitarists have protective cutouts on their leads.


The better valve ones did then too.

--
*How much deeper would the oceans be without sponges? *

Dave Plowman London SW
To e-mail, change noise into sound.
  #23   Report Post  
Andy Wade
 
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Default Cable colours for 110v fixed wiring

"Andy Hall" wrote in message
...

Like you say and Andrew had also suggested, large yellow cables seem
sensible.


The correct answer to your original question though is undoubtably (IMHO) to
use two reds (old colours) or browns (new colours). The conductors
concerned are phase conductors of a single-phase AC circuit. Neither is a
neutral because of the earthed centre tap.

If you use yellow then to comply with BS 7671 all terminations need to be
marked with red (brown if using new colours) sleeving. I agree with you
that the distributed centre tap is a circuit protective conductor, not a
neutral, and therfore should be grn/ylw and not black or blue.

It isn't even as though phase identification is important as it is
with three phase. Nevertheless, I'll probably connect it
consistently.


That's logical but not necessary. But I'd do the same :-)

IMO a better approach, if you're concerned about identifying individual
conductors or circuits in an installation where there's a large number of
wires in one trunking system, is to use the correct BS 7671 colours in
conjunction with wire number markings - for which systems are available from
RS, etc. (as you probably already know) - and to keep relevant
documentation.

--
Andy


  #24   Report Post  
Andy Hall
 
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Default Cable colours for 110v fixed wiring

On Sun, 27 Jun 2004 11:20:48 +0100, "Andy Wade"
wrote:

"Andy Hall" wrote in message
.. .

Like you say and Andrew had also suggested, large yellow cables seem
sensible.


The correct answer to your original question though is undoubtably (IMHO) to
use two reds (old colours) or browns (new colours). The conductors
concerned are phase conductors of a single-phase AC circuit. Neither is a
neutral because of the earthed centre tap.


This was one of my debates with myself because considering that it is
a centre tapped supply, there are, in effect, two phases albeit not
with the conventional 3 phase 120 degree shift. On the other hand,
the centre tap is not a current carrying conductor, so after thinking
some more I came to the same conclusion as you.

In fact what I've done is to use yellows but to put red markers at
each termination.

I've used numbers as well, but I had been using those as well because
there are becoming quite a large number of wires with all the radial
circuits for outlets and machines being run.


If you use yellow then to comply with BS 7671 all terminations need to be
marked with red (brown if using new colours) sleeving. I agree with you
that the distributed centre tap is a circuit protective conductor, not a
neutral, and therfore should be grn/ylw and not black or blue.

It isn't even as though phase identification is important as it is
with three phase. Nevertheless, I'll probably connect it
consistently.


That's logical but not necessary. But I'd do the same :-)

IMO a better approach, if you're concerned about identifying individual
conductors or circuits in an installation where there's a large number of
wires in one trunking system, is to use the correct BS 7671 colours in
conjunction with wire number markings - for which systems are available from
RS, etc. (as you probably already know) - and to keep relevant
documentation.


Yes, it's all going onto a spreadsheet.



..andy

To email, substitute .nospam with .gl
  #25   Report Post  
Andy Wade
 
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Default Cable colours for 110v fixed wiring

"Andy Hall" wrote in message
...

On Sun, 27 Jun 2004 11:20:48 +0100, "Andy Wade" wrote:
The conductors concerned are phase conductors of a single-phase AC
circuit. Neither is a neutral because of the earthed centre tap.


This was one of my debates with myself because considering that it is
a centre tapped supply, there are, in effect, two phases albeit not
with the conventional 3 phase 120 degree shift.


See sci.engr.electical.compliance /passim/ for interminable threads on the
subject of "is it 1-phase 3-wire or is it 2-phase?". I prefer the former,
reserving 2-phase to refer to two phases and neutral from a conventional
3-ph system, or two phases in quadrature.

On the other hand, the centre tap is not a current carrying
conductor, so after thinking some more I came to the same conclusion
as you.


Yes, in this case it's clearly a 2-wire single-phase circuit since there is
no third live [1] conductor. Since neither wire is a neutral (see
definition) they must both count as phase conductors (but are not separate
phases of a polyphase system). QED.

In fact what I've done is to use yellows but to put red markers at
each termination.


Fairynuff, that complies.

Yes, it's all going onto a spreadsheet.


A useful approach. I record things like the terminal numbers on neutral and
earth bars for each circuit from a dis-board in the same way.

[1] That's "live" in the BS 7671 sense of "load current carrying" - nothing
to do with the voltage above earth. C.f. "protective conductor.

--
Andy




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Andy Hall
 
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Default Cable colours for 110v fixed wiring

On Mon, 28 Jun 2004 10:28:59 +0100, "Andy Wade"
wrote:

"Andy Hall" wrote in message
.. .

On Sun, 27 Jun 2004 11:20:48 +0100, "Andy Wade" wrote:
The conductors concerned are phase conductors of a single-phase AC
circuit. Neither is a neutral because of the earthed centre tap.


This was one of my debates with myself because considering that it is
a centre tapped supply, there are, in effect, two phases albeit not
with the conventional 3 phase 120 degree shift.


See sci.engr.electical.compliance /passim/ for interminable threads on the
subject of "is it 1-phase 3-wire or is it 2-phase?". I prefer the former,
reserving 2-phase to refer to two phases and neutral from a conventional
3-ph system, or two phases in quadrature.


OK. This does make sense when presented that way, although I can't
think of many scenarios where you would have two out of three phases
used, apart perhaps, from wiring a large building with two phases only
on different floors, each single phase, and not needing the third.



On the other hand, the centre tap is not a current carrying
conductor, so after thinking some more I came to the same conclusion
as you.


Yes, in this case it's clearly a 2-wire single-phase circuit since there is
no third live [1] conductor. Since neither wire is a neutral (see
definition) they must both count as phase conductors (but are not separate
phases of a polyphase system). QED.


Make sense.


In fact what I've done is to use yellows but to put red markers at
each termination.


Fairynuff, that complies.

Yes, it's all going onto a spreadsheet.


A useful approach. I record things like the terminal numbers on neutral and
earth bars for each circuit from a dis-board in the same way.


Right. I've used the numbering from the bus bars and breakers,
keeping them consistent, and prefixing with a 1 or 2 to mark which of
the two stacked CUs.


[1] That's "live" in the BS 7671 sense of "load current carrying" - nothing
to do with the voltage above earth. C.f. "protective conductor.


..andy

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  #27   Report Post  
Lurch
 
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Default Cable colours for 110v fixed wiring

On Mon, 28 Jun 2004 11:05:36 +0100, Andy Hall
strung together this:

On Mon, 28 Jun 2004 10:28:59 +0100, "Andy Wade"
wrote:

"Andy Hall" wrote in message

I can't
think of many scenarios where you would have two out of three phases
used, apart perhaps, from wiring a large building with two phases only
on different floors, each single phase, and not needing the third.

Although not very common there are 2-phase appliances like welders and
other medium sized industrial machines.
--

SJW
A.C.S. Ltd
  #28   Report Post  
Terry
 
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Default Cable colours for 110v fixed wiring

On Sun, 27 Jun 2004 11:20:48 +0100, "Andy Wade" wrote:
The conductors concerned are phase conductors of a single-phase AC
circuit. Neither is a neutral because of the earthed centre tap.


This was one of my debates with myself because considering that it is
a centre tapped supply, there are, in effect, two phases albeit not
with the conventional 3 phase 120 degree shift.


See sci.engr.electical.compliance /passim/ for interminable threads on

the
subject of "is it 1-phase 3-wire or is it 2-phase?". I prefer the

former,
reserving 2-phase to refer to two phases and neutral from a conventional
3-ph system, or two phases in quadrature.



Same looseness of terminology used here in Canada. Unfortunately.
If the conductors are NOT actually the one, two or three phase wires of a
three phase system, why refer to them as 'phase wires' at all?
Why not use the term 'legs'.
Two examples come to mind;
On UK industrial sites AIUI transformers are used to step down 240 to 120
volts to power electric tools. A centre tap of the secondary of the
transformer is earthed. Hence we have two conductors at around 60 volts to
earth, for safety. Neither of those conductors are 'phase wires', they are
two conductors of the same single phase. (Although not correct for AC one
can almost think of them as plus 60 volts and minus 60 volts!).
Also. In North America atypical is a SINGLE phase 13,000 volt feed to the
local distribution transformer where it steps down to 230 volts centre
tapped.
Three wires come from each distribution transformer to several houses. The
centre tap is considered zero potential and is earthed; the maximum voltage
to earth is therefore 115 volts (RMS). The three wires are all on the same
single phase. In fact the nearest place, in our case, that three phase is
available is some distance away. Three phase is rarely, if ever supplied to
a domestic installation..
After the three wire service enters the house one of the legs is generally
black and the other red. The 115 volt loads are distributed, hopefully
evenly between the two legs and neutral, using single pole breakers. Heavier
loads such as water heaters, clothes dryers, electric cooking etc. are
connected between the two legs providing 230 volts using double pole
breakers.
But it's all single phase! 200 amp service at 230 volts (46Kva) is normal
these days for a typical house. Although I have seen one very large house
that had two such 200 amp services; they must have extra load such as a
indoor pool and/or some kind of elevator. (Growing marijuana also requires
much light btw!).


  #29   Report Post  
Andy Wade
 
Posts: n/a
Default Cable colours for 110v fixed wiring

"Lurch" wrote in message ...

Although not very common there are 2-phase appliances like welders
and other medium sized industrial machines.


Yes, but if they're just connected across 2 of the 3 phases then they're
really 400V single phase. (In principle you could run such an item off a
230V single phase supply using a step-up transformer.) Only if a neutral
connection is needed to provide a 230V supply for control circuits, or
whatever, would it be correct to describe it as 2-phase.

--
Andy


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