Electrician Talk banner
1 - 12 of 12 Posts

·
Electron Flow Consultant
Joined
·
3,309 Posts
Discussion Starter · #1 ·
What color do you designate as "+" for 2 wire instruments? Around here, with a few exceptions, black is always "+". This is true at most of the industrial facilities in the area. It is also shown this way in several tables in The Instrument Engineer's Handbook. What does everyone else see?
 

·
Bilge Rat
motors and controls.........
Joined
·
8,897 Posts
White pos here. Its preferred so if you have red/black and white/black cable in the same plant black is neg everywhere.
Same here, black is always – , and the other color is +.

Using black for + will cause confusion for anyone not familiar with the plants color code.

Come to think of it, I've never seen black used for +.
 

·
antisocial group ******
Joined
·
773 Posts
Black is always the low side here too. We will use any color OTHER then black for the high side.
 

·
Electron Flow Consultant
Joined
·
3,309 Posts
Discussion Starter · #7 ·
White pos here. Its preferred so if you have red/black and white/black cable in the same plant black is neg everywhere.
Nor sure why white would be +, not all cable has white, but they all have a black.
 

·
Electron Flow Consultant
Joined
·
3,309 Posts
Discussion Starter · #8 ·
Same here, black is always – , and the other color is +.

Using black for + will cause confusion for anyone not familiar with the plants color code.

Come to think of it, I've never seen black used for +.
Definitely important to know the color code at each facility, most of our sites have black as +, a few are the opposite. If you don't inform your crew, you can have big problems.
 

·
Registered
Joined
·
8,050 Posts
sparky970 said:
Definitely important to know the color code at each facility, most of our sites have black as +, a few are the opposite. If you don't inform your crew, you can have big problems.
Indeed. For us it varies by system. So our powder coat line might have one designation that you couldn't apply to the other side of the building with the torit or conveyor systems.

A little reconnaissance goes a long way in facilities
 

·
Registered
Joined
·
1,622 Posts
Since analog signals are DC, everywhere that I have ever worked, where cable was used, the black conductor was - (Neg.) and any other color was + (Pos.).
Of course, specs can vary from place to place and some places have no specs.
 

·
Registered
Joined
·
2,970 Posts
We did a terminal a few years ago where there was 2 different PLCs on site - 1 for the pipeline company and one for the storage company... Storage PLC and devices was all White positive.. Pipeline was all Black positive.. 2 transmitters on the same pipe, side by side were wired differently.. We had to have 2 separate crews doing the field device terminations - 1 for each method..

Colors mess up everyone... Number the wires and the problem would be solved.. #1 could be positive... In a multi pair cable same thing but it would be "-1"... It would clear up alot of problems... IMO
 

·
Registered
Joined
·
3,270 Posts
varmit said:
Since analog signals are DC, everywhere that I have ever worked, where cable was used, the black conductor was - (Neg.) and any other color was + (Pos.).
Of course, specs can vary from place to place and some places have no specs.
What he said
 
1 - 12 of 12 Posts
Top