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Old 12th Jun 2016, 2:24 pm   #1
camtechman
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Default Unsafe Wiring ? & Strange 3 Core Colours !

Just added a nice looking set of metal cased, Japanese wireless intercoms to my collection but, although I was keen to try them out, the colours of the 3 core wires of the mains leads made me hesitate !

So I set about dismantling the units to check them out to see where they were connected . Why the caution? Well the 3 wire colours are Blue, Pale Yellow & Orange and, although they had their mains plugs removed, from the length of the stripped back wires, where mains plugs were once fitted, it seemed to indicate that the blue wire was likely to be the neutral, the orange the live & the pale yellow the earth.

Sure enough, the blue was neutral, the orange was live & yellow the earth (but why those colours) ?

The next thing I saw amazed me !

The orange wire was soldered to an isolated PCB pad, from which it was also connected to a thinner red wire which, in turn, was connected to one side of a single pole switched 5K ohm volume control.

The other side of the switch then fed back an identical thin red wire to one of two primary connections of a smallish mains transformer. The only problem was the switched volume control was the same type used on Japanese pocket transistor radios.

So we've got 240 V AC passing through a less than robust, well known for causing crackling when operated ! Let alone not known for best insulation (but OK at 9V DC) between the switch contacts and in close proximity to the volume control connections.

The units have a label on the back stating 220-240 Volts (and not even A/C mentioned) and the whole PCB is fitted close to the metal casing and not a sight of any insulating material to keep both apart and not a sniff of any fuse!

From the style they could be late 60's to early 70's
I've provided a few pics to see what your thoughts are.
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Old 12th Jun 2016, 2:43 pm   #2
TonyDuell
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Default Re: Unsafe Wiring ? & Strange 3 Core Colours !

I wonder if the 'orange' is a corruption of 'brown' (either because the manufacuters mis-undersood the European colours or because the dye has changed with time) and that the 'yellow' is either 'green' that has changed in the same way or they misunderstood 'green and yellow' as 'green or yellow'.

In any case, like you I always check the internal wiring before fitting a plug. On anything old or new.
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Old 12th Jun 2016, 2:53 pm   #3
camtechman
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Default Re: Unsafe Wiring ? & Strange 3 Core Colours !

Having cut back the tatty mains plug ends and the internal end, the colours seem to be original and no fading.

The mains wire is unusually stout, a strong outer grey colour, which, when cut back, reveals a bluish/green inner insulation sleeve, on which is printed Jeon Dah PVC Cable, perhaps to meet UK standards. Shame the inner components are not as good.

If you hear a big bang, you'll know I tried my best LOL.
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Old 12th Jun 2016, 5:22 pm   #4
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Default Re: Unsafe Wiring ? & Strange 3 Core Colours !

I am happy go lucky, but appreciating just what mains can do take it easy so we get another post!
 
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