Correctly putting power plugs - polarization

Hi all,

I would like to check if I have all my power plugs connected to my powerblock correctly so asked an expert. He suggested the Ultimate Polarity Checker (Kemp electronics has one), but also a way simpler technique. With a screwdriver with embedded “voltage finder light” it is also possible. If you disconnect the IEC connector from a device and look straight into it (see my ugly picture below), then inserting the screwdriver in “A” should let the light go on. If it is “B” that puts the light on, the powercord is wrongly connected and should be changed.

I did the check and one (pre-amp) was wrong so I changed

I just want to be sure this is a valid way of checking. Do you guys recognize this and agree with the approach?



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It makes sense although I’ve never tried it. One side is live and the other is a neutral return.

You should perhaps state your location, as this issue will vary depending on the plug/socket arrangements used in your country, and many European countries are quite different to the UK in this respect.

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Hi @ChrisSU and @bruss , I am in Belgium so central Europe
The person telling me is somebody who is a professional in the music industry. He also lent me this Ultimate Polarity Checker that in the end checks the same but a way more complex process to get to the end result


IEC320 orientation is as shown in this drawing.
The “Socket (Female)” is the plug thats on the cable
The Live (L ) should light your voltage indicator (phase tester as you call it)
If the Neutral (N) lights the tester, you need to reverse the Schuko plug.


@Mike-B spot on; exactly what I tried to explain but you do so way better then me … thanks for the help

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so who is right? As i understand it IvdZ says that live is/should be on the right side and Mike-B on the left side as we face the male plug.

This was discussed recently Phase tester useful?

Depends on the unit. Naim units’ IEC sockets are correct and Naim’s included schuko-IEC power cords are marked on the respective live side of the schuko plug. The mark differs over the years, e.g., some older ones have a white paint marker spot (at least my CD5i-2 did, and a friend’s Nait 5i. So does the PowerIgel by the German Naim distributor, MusicLine). Others have a little riffle in the plastic of the plug. My dealer in Germany always pointed this out to me (and maybe the German distributor also added a little leaflet with the info at least in the past, but not sure if my recollection is correct and if they still do - can’t find it in the manual stash of last year’s purchases)

Non-Naim gear generally does not have this and indeed it happens that L and N on the IEC socket are not always where they should be. There are test devices for this, e.g. the Oehlbach phase tester or the Clear Components Phase Detector. You plug the IEC end of the power cord into the unit and the schuko end into the tester, then the tester lights up on the live side. There are some earlier threads about this which you will find when searching for these products.

Mike B is correct with his diagram.

Please don’t confuse this, my diagram is the IEC standard. No question, no confusion.

Maybe your confusion is the ‘male’ & ‘female’ description.
The Naim equipment has the male pins, the cable plug has the female sockets.


As he always is, it’s just with schuko plugs it’s not obvious on the other end.

So, say i plug the schuko plug on wall socket, then left side of female socket (as we face it) should light with a testing screwdriver, if not, i unplug schuko reverse it and reconnect back to the wall socket.
Is this a correct procedure for Naim components?

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Ah, there is no German/Austrian standard way but in France the regs say

" Looking into an outlet with the earth pin in the upper position, left is neutral and right is live*"
So on the plug, looking towards it then left is live.
However further confusion is that older properties may not be wired to these modern regs.

Yes, so long as all are the same at the IEC end then that’s what matters. FWIW, Musicline used to test all the Naim mains leads they supplied, as sometimes they could differ, and marked the positive at the schuko plug end with a dot.

Interestingly I found that the most important thing is to get everything in the Naim system the same, whether one way or the other, as this gave best performance.

It’s best never to assume that Schuko sockets, even in a mains extension strip, are correctly wired for polarity. All you need is a contactless induction pen to check this.


It’s mess with schuko :slight_smile: Your quote seems to be for the schuko socket, and there may well be a regulation in Germany as well (I’d be surprised if there was not). But as you said, you can’t much trust an unknown sparky who did the installation who-knows-when.

Trust will also depend on the age of the building, location, etc.; I once lived in an apartment in Berlin that had been wired in the GDR and a sparky, who I hired once to sort out some very weird things, gave up trying to understand what they had done, and just recommended not using certain wires.
FWIW, in my new German apartment building, live is left on the schuko sockets.

But there is the additional complication with the IEC-schuko cords, where you also can’t be always sure how the L/N of IEC ends are wired to the schuko ends (hence the Oehlbach tester and the like)

Correct, and I talek about the female connector on the cable so we agree @Mike-B @charnik

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Not for me. In fact I only changed 1 cable,being the power cable of the AQ Powerquest I use as net filter. All Naim boxes go into that and the phase tester had no use there.

Update for France and Naim plug.
The French socket with earth pin at the top. Looking at the wall socket, the live connection is the bottom LEFT.

This makes the iec connector at the Naim end of a Naim supplied lead give the live at the bottom RIGHT.

You still need to measure to be sure since someone can have swapped the wires.