Polarity Test - Extension Lead (surge protection) - Failed

[D J Sheridan]

Hi all,
This has got me stumped as it's the first time in 8 years this has happened.
I undertook a 250v test on a brand new recently purchased Surge Protection extension lead - all is well but on each of the 6 sockets it failed the Polarity Test.
Tested the IEC Lead and all was fine so not that, also plugged in the extension lead and all is okay with appliances connected to all 6 sockets... so much head scratching going on now.

Would you say this fails the extension lead? Or is it something to do with the Surge Protection system of it?

Cheers...

 

[Pete999]

What type and make is the SP device?

 

[pirate]

I had the same problem testing some surge protection leads.

The polarity test on the tester i use has limitations in the way it operates. This is necessary, as there is circuitry built in the machine to protect from miss-operation where for example IEC ( kettle ) leads have been plugged in to the tester while the other end is connected to the mains electricity supply. As you will appreciate this is both a completely incorrect thing to do, and potentially very dangerous.



The drawback is that the polarity test can be more sensitive than would be ideal. It is a situation where from a manufacturer's perspective safety has to override some compromise in performance.



One consequence is that some surge protected leads can cause a ‘false fail’ indication on polarity as the surge suppression components allow a small current to flow between live and neutral, which the machine incorrectly interprets as a fault current.

My thanks to Nigel Croucher for the above explanation.

 

[D J Sheridan]

What type and make is the SP device?

Belkin Surgestrip - 3 meters 6 sockets.

 

[pirate]

Coincidentally, the fails i had were on Belkin units too.

 

[D J Sheridan]

Coincidentally, the fails i had were on Belkin units too.

Hi,
I thought this might be the reason regarding the slight current between Live and Neutral (it states on the PA Tester L and N Shorted).
But I would have thought that during the Polarity test there is no power going through the extension? As am I right in thinking that Surge Protected Extension the SP system only works when under power (IE: as when plugged in and switched on as it 'monitors' the circuits? - a green LED is lit to state SP in operation).
So by all accounts then the pathway to allow the slight current between L and N is causing the problem?

 

[static zap]

I undertook a 250v test

Is that a 250V DC test or , or AC active via tester ?
( alternatively -what tester is being used )
...I suspect these testers err on the side of safety / not actually designed to pass SPDs ..

 

[D J Sheridan]

Is that a 250V DC test or , or AC active via tester ?
( alternatively -what tester is being used )
...I suspect these testers err on the side of safety / not actually designed to pass SPDs ..

It's a Metrel Omega PA Tester.
I use a 250v test instead of 500v as 500v will fail the test.
The fail I have is for the last test which is Polarity.

 

[multimick]

my pat tester megger 120 also fails all of these , on polarity a little common sense is needed ,i use my mft to test these now

 

[D J Sheridan]

my pat tester megger 120 also fails all of these , on polarity a little common sense is needed ,i use my mft to test these now

MFT... I take it a Multifunction Tester?
So I suppose just you an MFT and do a continuity test on the earth to earth pin / live to live pin and neutral to neutral pin?

 

[multimick]

yes correct and the most important one which is visual.

 

[D J Sheridan]

yes correct and the most important one which is visual.

All new and visual check is fine... but it is a sealed unit so can't even remove the back to check visually that way either.