Any advice on how to proceed with these 4 wires ?
Switch off any breaker even remotely likely to power this setup.
With your double wide box labelled as #1 and the other two boxes labelled as #2 and #3 and the four yellow wires in box #1 labelled as A, B, C & D,
run your ohmmeter with its extension cord from a yellow wire in box #2 to each of the four unconnected yellow wire ends in box #1. But first put your meter on the 240vac scale and check for 'zero' voltage; you never know.
Repeat for box #3.
4 +3 +2 + 1 = 10 tests in all.
If you can't get 'zero' voltage turn off your main breaker and try again.
In principle an AC voltage should not affect an ohmmeter that uses DC current to test the resistance, but the real world is not quite so predictable.
I've never put my test procedure in writing because it's in my head and some of it may depend on instinct.
Since you might have this fixed by now without this procedure, I'll post it in chunks as the need arises. Here are the cases covered so far for an unidentified wire of indeterminate color coming out of a resi. box:
Distant Wire End [E] has on it. . .
120v w/respect to ground [E1] or
ground [E2] or
open [E3] or
other?
Wire Middle [M] has in it. . .
splice, good or bad, with different color on each side or not [M1], or
lamp [M2] or
switch [M3] or
other?
Any other real-life cases are certainly welcome.
Maybe this will turn lurkers into members.
http://en.wikipedia.org/wiki/1%_rule_(Internet_culture)
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The 1% rule states that the number of people who create content on the internet represents approximately 1% (or less) of the people actually viewing that content (e.g., For every one person who posts on a forum, there are at least ninety-nine other people viewing that forum but not posting). The term was coined by authors and bloggers Ben McConnell and Jackie Huba[1] although there are earlier references to the same concept[2] that did not use this name.
The "90-9-1" version of this rule states that 1% of people create content, 9% edit or modify that content, and 90% view the content without contributing.
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