Black and blue wires in light switch


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Old 02-19-17, 03:58 PM
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Black and blue wires in light switch

Hi all, I am trying to replace an existing switch with a new wifi switch. Unfortunately when I opened the current switch the wires make no sense to me. This house is from 1967. Photos included. I know that grounding switches wasn't code back then so I only expected to see a live and a neutral, but has neutral ever been blue?! Also when I disconnected the switch it looks like the black wire was looped. Any idea on how to solve this conundrum, or will I have to live with the old switch until I get new wiring?

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Last edited by PJmax; 02-19-17 at 04:05 PM. Reason: added pics from links
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Old 02-19-17, 04:09 PM
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Welcome to the forums.

You have different colors then you are used to seeing because your wiring is in conduit. There was no neutral required for any standard switch in the past.
Now....by code.... a neutral must be in every switch box.

I see the neutral wire in the back of the box.
See if you can carefully pull a loop out of the box.
 
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Old 02-19-17, 04:14 PM
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expected to see a live and a neutral
For that time period I expect a switch loop, only a hot in and a hot out. Only white and gray can be neutral. Green, Green/Yellow, bare are the only ground colors, all other colors are hots. I would expect the wiring to be in conduit* if there is a blue, is it? If so you may be able to pull a neutral.

*4-conductor cable has a blue but I wouldn't expect it in old residential wiring.

OOPS Pete types faster.
 
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Old 02-19-17, 04:17 PM
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I changed my reply three times. I missed the wifi switch addition.

That is a 1900 (4"sq) box so I'm pretty sure it's a conduit system.
 
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Old 02-19-17, 06:00 PM
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Conduit

Hi all--thank you for the replies!

1) Yes, it is definitely a conduit system (metallic).

2) Just to confirm your responses, does that mean that both the black and the blue wires are live, the white is neutral and there just is no ground at all?

3) For installing my new switch [which uses 2x black (live) 1x white (neutral) and 1x green (ground {optional})]. I would connect:

black-black,
black-blue,
*carefully* pull the neutral and connect white-white,
cap off the green ground wire which will not be in use.
 
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Old 02-19-17, 06:09 PM
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There should be a tapped/threaded hole in the back of the box for a ground screw. Not super critical in that application as the switch gets its ground thru the two mounting screws and the box which is grounded via the conduit.

Correct.... the two blacks which is currently a loop is your hot and goes to the hot wire of the switch. The blue is the light or load wire and white is neutral.
 
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Old 02-19-17, 06:11 PM
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With the switch design being a little different, could you fill out your profile and let us know where you are located? It may be a different electrical system than we have in North America.
 
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Old 02-19-17, 06:41 PM
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Thanks!

I filled out my profile, but it all makes sense now knowing the blue is the light/load wire. We will attempt the change out and let you know how it goes.

UPDATE: We got the wifi switch hooked up and it is working like a dream thanks to you all!
 

Last edited by Meghan Glæs; 02-19-17 at 07:06 PM.
 

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