ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Top Posters(30 Days)
Potseal 11
Recent Posts
Permit Snafus...AHJs and Contractors Jump in
by sparky. 04/29/17 05:59 PM
201 volt equipment?
by bigpapa. 04/29/17 12:15 AM
Schneider LC1D09
by jraef. 04/28/17 11:05 PM
Electrode boilers question
by annemarie1. 04/27/17 01:40 PM
Why cables look like they do
by LongRunner. 04/26/17 09:36 AM
New in the Gallery:
SE cable question
Popular Topics(Views)
235,003 Are you busy
169,843 Re: Forum
163,043 Need opinion
Who's Online Now
0 registered members (), 40 guests, and 11 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
#23378 - 03/16/03 07:25 PM History of color coding?  
rmiell  Offline
Member
Joined: Nov 2000
Posts: 242
La Junta, Co. USA
Anyone have any history about when and why the present use of black for hot and white for neutral(grounded) for AC, while red is used for positive and black for negative in DC, came into being?

Did Edison or Tesla ever get into this?

Thanks

Rick Miell


Work Gear for Electricians and the Trades

#23379 - 03/17/03 12:21 AM Re: History of color coding?  
DBC1  Offline
Member
Joined: Mar 2003
Posts: 16
Tulsa, OK USA
Rick, sorry cannot help with when black and white were used for AC circuits.

But you are mistaken about your DC colors. There is no color code for DC. Each industry does there own thing. Walk into any telephone office and it will vary from office to office. The positive is black because it is the grounded conductor, just the oppisite of ac. The negative, or hot, can be black, white, blue, or red. It's just to confuse the Russian's. [Linked Image]


#23380 - 03/17/03 09:25 AM Re: History of color coding?  
electure  Offline


Member
Joined: Dec 2000
Posts: 4,259
Fullerton, CA USA
Rick,
My earliest reference book, 1924, makes no mention of any colors for AC or DC.
It does refer to "neutral", but doesn't say anything about grounding it. The only mention of grounding is that NM Cable contained a wire 2 sizes smaller than the others, which should be used for grounding of metal boxes...S


#23381 - 03/17/03 07:47 PM Re: History of color coding?  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Rick,
You may have already seen this, but we had quite a discussion on the color codes, past and present, of various countries. The thread is here with a condensed summary posted in the technical reference section here .

These just go to show that what might seem to be an "obvious" choice of colors to somebody who grew up with them, might not be to somebody else.

In the West we accept red and black as common colors for positive and negative on D.C., such as on test leads, but I have a Russian-made meter which has white and black leads and probes (I still have no idea which way round the Russians use them.)

On the D.C. issue, here in England black was adopted for the grounded pole of a D.C. system (as it is with A.C. systems). Red and blue were then used for D.C. lines positive or negative with respect to ground on a 3-wire system, but our "code" for building wiring specified that the hot pole of a 2-wire DC circuit should be red, even where it waa derived from the negative side of a 3w DC system!

You can see the red/blue coding on D.C. switchgear on the London Underground (subway system) and elsewhere. For example, in old G.P.O. telephone offices the positive (grounded) busbar was bare while the negative busbar was identified blue.

I too would be interested to learn when the common American colors came into general use, and/or when they were first specified by the NEC.



Member Spotlight
SafetyWired
SafetyWired
Pa, USA
Posts: 44
Joined: July 2013
Show All Member Profiles 
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.010s Queries: 14 (0.002s) Memory: 0.7612 MB (Peak: 0.8924 MB) Zlib enabled. Server Time: 2017-04-30 11:02:34 UTC