Polarised vs Un-Polarised C7 Connectors

[Daniel Heard]

Hi all,

I own a Numark NDX500 which requires a 'polarised C7' connector (C7P).

https://en.wikipedia.org/wiki/IEC_60320#/media/File:IEC_60320_C7P_Polarised.png

However this is very hard to find, I am awaiting a reply from the manufacturer.

Question is, would it be safe to use the non-polarised version instead as I have a few of those?

https://en.wikipedia.org/wiki/IEC_60320#/media/File:IEC_60320_C7.svg

If not, where would I be able to obtain one with a UK plug? I have found one here and wonder if it would be safe...

http://www.parts-express.com/bs-1363-uk-2-pole-plug-to-c7p-polarized-6-ft-power-cord-fused-10a-18-2--110-116

Many thanks,

Dan.

 

[steptoe]

Polarised should be easy enough to obtain, 

I have a couple of them,

Do NOT use un polarised if it requires polarised. 

Have a search of CPC

 

[Daniel Heard]

Thanks Steptoe,

Thing is, they are not that easy to find at all. Unless you can provide some links to them?

I've managed to find this but ships from the US.

http://www.parts-express.com/bs-1363-uk-2-pole-plug-to-c7p-polarized-6-ft-power-cord-fused-10a-18-2--110-116

Dan.

 

[Daniel Heard]

I have emailed CPC in the meantime.

 

[Sidewinder]

It looks like the C7p is not popular in Europe, even though it's an IEC connector, I don't think it's an official one.

They seem common enough in the USA.

If you are more comfortable purchasing in the UK/EU, then Mouser have one, but, including shipping it's about £15 plus vat, and, it has a NEMA plug, so you'd have to fit a BS1363, &, get the polarity right.

Link here:

http://www.mouser.co.uk/Search/ProductDetail.aspx?R=223083-01virtualkey56210000virtualkey562-223083-01

However, I have just looked at the link again & the data sheet, it is only rated @ 125V, so not suitable for use in the UK @ 230 V.

 

[Andy™]

did you buy this new? if so, they it should have came with a suitable lead with a 1363 plug on it

 

[Apache]

If it's going into the mains then how can it matter with AC????

I don't get it - if a normal one fits

 

[Blue Duck]

Probably won't fit.

I had some active monitors with funny 2 pin kettle plugs (IEC?) an remember being perplexed when trying to use a normal lead.

Music equipment is funny like that, there must be a reason.

Have you tried Numark ? 

 

[Daniel Heard]

Finally heard back from Numark (inMusic) today, and they assure me that a standard UK C7 works fine on my model due to the internals being capable.

Thanks all for your help.

 

[Andy™]

looks like a stand alone thing. since its only got a 2 pin connector then it must be class 2. cant see any reason why polarity would matter. plenty other similar items that all manage with the usual fig 8 lead. most likely goes straight to a transformer anyway

 

[ProDave]

The only reason it can matter, is if it uses a single pole on off switch in the mains. Then it only really "matters" if you have the thing in bits and are fault finding on it.  With the case all screwed together and in normal use I can't see much problem if the polarity was wrong.
 

 

[Blue Duck]

I would have assumed that there is some kind of 'noise' filtering on the live for countries or places  with lumpy electricity or in studios where there is a lot of equipment that may cause some interference.

just assuming..

 

[Bruspark]

The other reason polarisation coud matter is if there is a metallic part or output on the device.  For example many small Switched Mode power supplies for USB charging
or even laptop supplies lack both fixed polarisation and a connected 'E' pin.  They both have metallic 'outputs' .   They therefore HAVE to output their 5 or 12V DC output pins or whatever floating 'unloaded' somewhere between the two AC input potentials above ground.  

Ideally if no 'E' is available the (Neutral) input polarity is mechanically 'fixed' and the designer can then ensure the output/metalwork floats nearer to Neutral which in turn is safely near Ground.  

For the reversible C7 type and assemble-able plug/PSU devices this cannot always be guaranteed and so the DC voltage floats between L and N but often it looks more like 80V from one and 150V from another.  
The little power supplies that come with TVsticks look like this (and LN polarity of those is reversible according to plug/SMPS assembly).   Therefore plugging such a TV stick or a 2 pin Mains powered notebook into the HDMI socket of a grounded AV system can give quite visible sparks that are bigger one way round.  

Of course once plugged the AV system easily pulls the high impedance sourced 'floating voltage' down but maybe only after the HDMI board silicon is expensively blown . .  If the other equipment is metallic but not grounded we get the 'my phone tingles when it's charging?' effect.

When a supplier says it's not a problem it usually means they know an output is floating 'midway' but the current capability at the float voltage is very low and thus safety compliant (which it probably is and has to be that way in certain other counties where Earth pins are optional and socket polarity a bit variable).