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Discussion Starter #1
Hi there

I live in the UK and have a compressor (of the music effects unit variety) which I bought set at 115v with a US Type A, Unpolarised plug attached. In one of the old maunals for the unit (there were several revisions), it advised UK users who wished to change to UK plugs that it was wired Blue:Neutral and Brown:Live etc. Also stating that the plug required a 3 Amp fuse. Straight forward enough I thought. Therefore, I switched the unit to 230v with the switch on the back and cut off the plug with the intention of putting a UK plug on it.

However, on cutting the US Type A, Unpolarised plug off the cable which is a two cable conjoined cable (kinda like headphone wire), I found out that this outer layer was the only thing covering the copper wire inside. Therefore, there are no colours there to wire correctly into a UK plug.

Would it matter which way around the two wires are wired into a UK plug? Doesn't the unpolarised apply to the UK too dependent on the unit being supplied the power?

What is the likely outcome should this wiring be wrong if the unit is switched on?


Kindest regards

R.
 

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If it has an unpolarized plug on the unit it should be double insulated (unless a very old unit) and it shouldn't matter which wire is which. However it is always a good idea to check for continuity between the wires and any metal frame.
 

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Odd that it would be unpolarized, even if double insulated. But in the U.S. we usually identify which wire in neutral, even when the wires are the same color. Sometimes one wire will have small type letters. Or it may have ridges. This is the neutral.
 

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Discussion Starter #5 (Edited)
Hi there

Thank you very much for your replies everyone. I'll be sure to check that link Yoyizit.

Well...The unit works just fine wired into a UK plug.

Yes InPhase277 and hayewe farm. It's an old unit. From the 1980s I believe. This is probably why it lacks the additional layer of insulation.

When I got the unit, it was set to 115v. Therefore, being in the UK I used a step down transfomer with it. Once I realised it had a recessed and covered voltage switch on the back, I changed it to 230v and used a US to UK adapter. However, my confusion began when I had the bright idea of putting a UK plug on the thing yesterday evening.

Given what a couple of you have said regarding the polarity not beng an issue, and having had a look inside the US to UK adapter I've been using this past 8 weeks (see pics), it was apparent that this adapter didn't have anything fancy inside that would have made allowances for wrong wiring etc.





Therefore, using this adapter with the Type A, unpolarised US plug plugged into it either way around, would have presented each wire (in my unit's mains cable) to different UK plug pins. This surely means that my wiring of the UK plug (instead of continuing US to UK adapter) will have changed nothing safety-wise? Providing my plug is wired securely of course.

Incidentally, there were no ridges or markings on any of the cables. Do you thinnk it would be wise to take it somewhere to have a better cable (double insulated) put in and have it checked out? The person who had it before me had it for 20 years with it running smoothly without incidence.


Kindest Regards and Thanks

R.
 

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Thanks hayewe farm

This is beyond my capabilities and would likely have to be someone else. How would this be done though?


Regards

R.
You could do it with a cheap test meter found at the hardware store. But likely, if it had plug with no ground (you call it earth) pin, and it was made as recently as the 1980s, it is probably fine either way it is wired. AC doesn't care which wire is which, and the electronics within the device regulate the power once it is there.

Also, there may be a fuse inside the unit. If you feel like looking, the live wire will be the one connected to the fuse.
 

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Discussion Starter #8
Thanks InPhase277

I actually took a couple of pics when the unit (dbx compressor) was open. They are here. Note: that they were taken from the front of the unit looking toward the rear. Apologies for the first one being blurred.

There appear to be 3 wires which come from the a plastic part at the back of the unit, this I think is the voltage selecter switch on the back of the unit. These are not the cable wires which exit the unit (to a plug) but are before this stage. Looking at these wires from the front of the unit looking towards the back, they appear to be a Red (Left), Black (Centre) and an additional Black (Right). See first pic.

The Centre Black wire becomes one of my two conjoined mains wires which exit from the rear. The other two wires - the Red (Left) and Black (Right) go into the NTK gold coloured Transformer.

A White wire comes out of the NTK Transformer and goes into a white plastic cap where it appears to terminate (see pic 2). Out of this plastic cap, a Black wire comes out. This Black wire is the second of my pair of conjoined mains cable wires.

Does this look right to you?

There's a schematic here with the voltage selector etc at the bottom left of the page. I don't know if there's a fuse though. I have a 3 amp one in my plug.


Thanks and kindest regards

R.
 

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On double insulated devices the choice of which is grounded doesn't matter except with lights. You always want the ungrounded lead tied to the center button because you might come into contact with the outer edge of the base and you always want that to be tied to the grounded leg.
 

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Ok, the pics and the description helped alot. In the U.S. we use white as the neutral wire. The wire of the cord that is connected to the transformer's white wire needs to be connected to the neutral pin of your plug.
 

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Ok, the pics and the description helped alot. In the U.S. we use white as the neutral wire. The wire of the cord that is connected to the transformer's white wire needs to be connected to the neutral pin of your plug.
It is totally unneccessary to worry about which wire is hooked to the grounded leg. With a nonpolerized plug it could be pluged in so the hot or the neutral was hooked to the white wire.
 

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It is totally unneccessary to worry about which wire is hooked to the grounded leg. With a nonpolerized plug it could be pluged in so the hot or the neutral was hooked to the white wire.
For all we know, the OP meant unpolarized in that it didn't have a ground pin. Someone not familiar with U.S. plugs may not have noticed one blade wider than the other. In any case, while it may work either way, the manufacturer had a clear intent in mind when they wired the thing. The hot line goes to the voltage selector switch, and the neutral goes straight to the transformer. It would be best to stick to this convention.
 

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All windings of a transformer are isolated and insulated. The lead wire colors are pole designations and have little to do with conventions. The leads connect to no other device and there is no on/off switch. There would be no benefit in redoing the wiring.
 

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All windings of a transformer are isolated and insulated. The lead wire colors are pole designations and have little to do with conventions. The leads connect to no other device and there is no on/off switch. There would be no benefit in redoing the wiring.
Why are you so against the guy doing it right?
 

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I just believe that in this case there is no right or wrong. Having bought hundreds of transformers even ones with the same part number with different colored wires for the poles. There is no standard for the transformers.
 

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I just believe that in this case there is no right or wrong. Having bought hundreds of transformers even ones with the same part number with different colored wires for the poles. There is no standard for the transformers.
You are right that there is no standard for the transformers, but there is a convention on which wire we switch and which one we send straight through. The hot live wire is connected to the voltage selector switch, and the grounded neutral goes straight in. Does it really matter from a physics standpoint? No, but it is best to follow the established convention for these kinds of things.
 

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Discussion Starter #17
Hi Again

You're both being very kind in helping my out with this. Thank you so much.

I've kinda understood what you've been talking about. However, were you both assuming I had a plug with one pin wider then the other?

What I had on the unit was a 2-pin unpolarized Type A plug (both pins exactly the same size). Here's a pic:



As it stands (with the unit working fine), it appears my Neutral wire (in the unit) is wired to Live in my UK plug and that the Live wire (in the unit) is wired to Neutral in my UK plug.

Am I being advised to change yhe wires in my plug around for piece of mind to have adhered to convention?

And, on the other hand, not to bother?


Regards

R.
 

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InPhase277 is suggesting you rewire to follow convention my point is it will have no detriment effect wired either way and not affect the operation. It's your unit so it's entirely up to you. The discussion has to do with point of view rather than safety or function. If the unit was much older, say 1950 or older, it would be important because it was common to bond one line to the chassis.
 

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You are right that there is no standard for the transformers, but there is a convention on which wire we switch and which one we send straight through. The hot live wire is connected to the voltage selector switch, and the grounded neutral goes straight in. Does it really matter from a physics standpoint? No, but it is best to follow the established convention for these kinds of things.
If it was an on/off switch I would agree. However there are production and service advantages in wiring voltage selector switches to the grounded conductor. The terminals do not need to be heat shrinked or insulated which cuts production costs and allows for easier replacement. Both conductors in this type of application are considered straight through.
 

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Discussion Starter #20
Hi Again

I just want to thank you both for your help here. You've both been very supportive.


Thanks again. Much appreciated.

R.
 
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