Mnemonic aid for blue=white, brown=black (120V AC mains)

I don't have any trouble equating brown and black wires. Blue is the tint of very white light such as "pure" white LEDs.

I *have* always thought it odd that the "cooler" color temperatures at the 2700 K end of color temperature is considered "warm" white while the higher color temperatures around 4000 K are considered "cool". Does that make sense?

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Rick C

In the R.O.W. (rest of world, i.e outside USA) where IEC coloUrs prevail, brown is active and blue is neutral.

Black or Brown will knock you down.

Brown is hot, brown is burnt.

#brownwiresmatter

When I was first rewiring plugs (when I took toy train controllers around to a friend that only had the obsolete 5A sockets), red=live, black=neutral, green=earth.

So the progression to brown=live blue=neutral green/yellow=earth was easy: brown ~= red blue ~= black. Or, if you prefer, brown is "hotter" than blue.

Here, there are few constants.

E.g., in "electronics", 0V is typically black with +V being red (often).

[I've seen places adopt "warm" colors (red, orange, yellow) for positive voltages with "cool" colors (blue, violet) for negative supplies.]

In a regular 120VAC branch circuit, black is (instead!) *hot* while white is neutral.

The second hot in a cable is typically red (i.e., a 3 conductor + ground cable is black/red/white/copper).

Green, of course, being "earth"/safety ground.

However, ANY color other than green/grey/white can be used to carry power (hot). So, a BLUE conductor -- *or* a BROWN conductor -- can also be "hot".

I.e., white/grey/green/bare are (reasonably) safe (with which to come into contact) -- unless a (e.g., white!) wire is "taped black", etc.

The brown/blue/green issue obviously relies on context to ensure the "proper" interpretation for these "non-neutral" colors.

Green things are usually alive. Earth is usually brown. Black things are often dead although black lives matter. Green and yellow things (eg primroses) are alive too. At least white is a sort of neutral colour. Blue is cold, although the earth is blue from space.

It makes little sense. From today, the new global standard shall be:

Red - live/hot Grey - neutral Brown - earth/ground

The old colours here were red, black and green for LNE. With slightly grubby rubber cable, my father, who is red/green colour-blind, consistently swapped red and green when wiring the garage. That caused a problem for me when adding an extra socket.

Cheers

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Syd

Unfortunately 8% of men (

One could easily associate "alive" with "live" (i.e., hot) -- which is definitely not the case.

Blue could be equated with "sky" -- which wouldn't suggest "ground".

All of this rationale would be a stretch (IMO).

For blue/brown/green in the context of a power cord, green == safety ground is a no-brainer. Beyond that, blue is closer to white in the (resistor) color code -- while brown (and red!) are closer to black.

The trouble comes (in the US) in that anything other than green/grey/white can "be hot" (or a traveler). So, when faced with two colors that could

*potentially* be hot (blue and brown), I take pause and have to think: "which is more likely to be neutral". Then, I rattle off the color code in my head and bind blue/brown to white/black as a result.

I find this a tedious process; I just *remember* white and green as neutral; no association required! Looking for something similar for blue/brown. You want to be *sure* when facing potentially live circuits -- not hesitating to go through this contrived "resistor color code" association...

When *anyone* (DIYer) wires something, all bets are off.

We had a wall-switch, here, in the garage, that "didn't appear to DO anything". You'd flip it on, then off, and nothing would visibly change. One day, while playing with it, I caught a shock from touching one of the (visible) mounting screws for the cover plate.

Took the thing out of the Jbox and discovered that it was wired wrong: the traveler was wired to the GREEN screw on the switch: "Hmmm, what do I do with this OTHER (colored) wire? Only three places where it can be connected...

*Should* have been a "three-way" (SPDT) switch but the DIY-er obviously didn't understand that when he installed the regular switch (SPST) in its place. As a result, the mounts would be attached to the traveler -- which could be at line potential depending on the position of the *other* 3-way switch in the circuit.

In another home, I found a kitchen duplex receptacle tied to black and red. And, folks wondered why anything plugged into it promptly failed!

Blue is Cool (neutral) Brown is Hot

Cheers

Yes, that is what the OP is referring to. Here black is hot and white is neutral while in the rest of the world brown is hot and blue neutral, so he is asking for a way to easily remember this since we don't see the international colors so often.

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Rick C

If the circuit is live, just scratch the wire in question against a known ground.

It should be pretty obvious which is which.

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Tim Wescott 
Control systems, embedded software and circuit design 

For UK 240V , 3 wire, someone not technical, once told me , this is what was what, well it is at least logical , unfortunately highly dangerous. The stripey yellow and green one , marked like a snake, is the dangerous one so must be the live wire, the brown one is earth colour so must be earth, leaving just the blue for the remaining one.

The racist way..youall be white you blue-blooded Brit; de slaves be black or brown, Sho 'nuff.

over here black is neutral and red is live, so it's just the closest colour...

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This email has not been checked by half-arsed antivirus software

Actually from AS/NZ3000:2007 (and onwards) Clause 3.8.1:

"Where identification is achieved using the colour of the conductor insulation, the coulrs specified in Table 3.4 shall be used/"

and Table 3.4: *earth is green/yellow *neutral is black or light blue *active is "any colour other than green, yellow, green/yellow, black or light blue"

while the recommended colours for actives are: *red or brown for single phase *red,white or dark blue for multiphase.

There is of course a HUGE amount of legacy installation out there, using red-black-green or red-black-green/yellow.

Maybe try a mnemonic to remember what's wrong instead of what's right, like "black and blue will undo hue."

or if you are in a black/white world with brown/light_blue as the alternative (NOT old red/black ...)

"black and red both leave you dead".