IEC 320 C14 Strange Wiring in Device From Japan

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ambd1

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Hi,

I hope you are well. I am new to the forum, so I thank you in advance for you help.

I have a tube amplifier from Japan that came with a very strange wiring in a fused power switch IEC 320 C14. I am located in the United States. I have already dealt with the difference in voltage between Japan and the US, but I am having trouble understanding why the power switch came wired in this strange way.

This is the front side of the fused power switch.



Please find below what I believe is the correct wiring for a fused power switch IEC 320 C14 for the United States.



And, below is the wiring for that power switch in this Japanese amplifier. I have marked some connections with yellow and red, only as reference to the cables coming from inside the amplifier, as I do not know yet which one is neutral and which one is hot.



The fact that the jumpers for hot and neutral coming from the IEC do not go to the same positions (as per the correct wiring) on the switch side would only matter if this switch when OFF only cuts the live/hot wire connection, right? If the power switch actually cuts both, neutral and hot, when OFF then it does not matter where the jumpers go on the right side, as long as both go on the narrow (lower) pair of electrodes, is that correct?

But, why the cable in yellow is connected to the fused hot? sort of bypassing the power switch? I know Japan current is mostly not polarized, but in the United States, what would be the correct way of wiring this for the amplifier?

Any help would be greatly welcome.

Thanks,

Alan
 

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It's usual to have the fuse and switch in the live side, but there will be no difference in behaviour if one or both of those is in the neutral connections. If the neutral is turned off by a switch or by a fuse, the whole mains side will be live, but unless there is a problem with the isolation, that make no difference.

Many mains power connectors are not polarised. Mains connectors in much of Europe are not polarised, and the C7/C8 connectors aren't polarised. Bayonet lamps aren't polarised. If there is ever a fuse or switch after a non-polarised connector, the switch and fuse can end up on the neutral side.

If unpolarised connectors are not likely to be used, there is no incentive for a manufacturer to keep the switch and fuse in the live side, as the user can just plug it in the other way round.

The lamp need both live and neutral connections to work, so if the switch contains a lamp, the assembly will need both live and neutral connections.

The switch can be double pole to isolate both live and neutral.

In the end, as long as the switch and the fuse are both in series with the supply, it doesn't matter which lead they are in. If you want to rewire the back of the inlet to keep the fuse and switch in the live side, go ahead.
 
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Thanks for your help.

But, and I apologize if this should be evident for me, so you are implying that in this case the red cable is the live/hot, right? Because if the yellow cable is live/hot then when the power switch is in the OFF position, the yellow cable will not be affected by the switch since it is not connected to it.

And, then, what would the safe/proper way to wire this to be used in the United States?

Thanks,
 
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The if the yellow wire is live / hot, and the switch is off, the yellow cable will not be affected.

However,
1) the appliance will be turned off as there is no return path
2) It doesn't matter that all the live / neutral connections are now live because you should never rely on a switch to make stuff safe to work on. There is no substitute for unplugging.
 
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ambd1 said:
And, then, what would the safe/proper way to wire this to be used in the United States?
Click to expand...
Any method that has a fuse and a switch in circuit is safe and proper. Either the fuse or the switch can turn off the appliance, and all of the hot/neutral wiring should always be considered live unless unplugged.

I suppose that the best would be a polarised plug, a double pole switch and a fuse in the live, but there is no practical advantage.
 
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Thanks for your help!

Yes, as you said, a double pole fused would be better. But, if I would to keep this switch in place of the amplifier, and if I do not want to be unplugging it every time I will use it, is the wiring as it is now OK in terms of not getting a shock when touching it or using it? or should I change something?
 
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You could just move the connection from the direct live to switched live.

I would never knowingly leave anything with only neutral switched - you never know what may happen or who may work on it in the future.


I had an experience with something similar in the 70s; I was helping out in a small electronics shop and the owners son, who lived in the flat above the shop at the time, came in with a new, freestanding "electric fire" wanting a plug for it. I offered to fit it but he refused, saying he could do it.

A few days later his toddler-age daughter started examining the fire whilst it was turned off, put her hand through the chrome bars and grabbed the wire wound ceramic element.

She got severe burns as the guy had wired the plug backwards & the fire only had a single-pole switch - which disconnected the neutral due to the reversed wiring; the element was permanently live.

Never switch a neutral only!
 
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Hardly - many electrical/electronic items switch the neutral instead of the live, it really makes very little difference.

However, from a personal point of view, I'd always switch the live (or both) if I was wiring something - however, I wouldn't change a commercial product that was wired the other way, as it already meets all required legislation, and any such unauthorised modification means that you are then personally responsible for anything that might happen to it in the future.

Interestingly, I've recently wired the exact same socket/fuse/switch assembly as in the pictures - it's simple enough, the live output from the fuse goes to the input of the switch, and the output is taken from the output of the switch - the neutral from the socket is linked to the other connection of the neon in the switch, the other neon connection is linked internally to the output of the switch. Best to measure which pin is which first, and particularly which pin of the s=witch is the output, and has the neon connected to it.
 
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Thanks for the suggestion, and thanks for sharing that story,

That is unfortunate. That is why is always better to be cautious and respect electricity.

So, I guess that I should just move the yellow cable (assuming yellow is hot) as in the image below



or I should completely rewire it like below?
Because, if this switch is just a single pole switch, as I think it is, in OFF position it will only block current on one side, the live/hot side (inside a yellow rectangle on the image below), and it will not block current on the other side. So, for OFF position to effectively block the live/hot, the live/hot coming from the IEC on the left needs to be connected with a jumper to the lower electrode inside the yellow rectangle, and not to the lower electrode to the right side. Or I am missing something?

 
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