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Round pin 15amp plugs

PostPosted: Wed Apr 18, 2012 12:00 pm
by Matt Macdermott
Thanks Grizzly & led for advice on studio equipment. I've just been testing a load of round pin-plugged items, mostly stage lights; I noticed that none of these plugs have protection on the live and neutral pins. Is this normal or should they all be failed as normal square pin plugs would be?

Re: Round pin 15amp plugs

PostPosted: Wed Apr 18, 2012 12:21 pm
by Alan Freeman
Matt

The insulation on a 13A plug is unique to 13A plugs.

The only place you should find 15A round pin plugs now is in entertainment for the lighting.

Re: Round pin 15amp plugs

PostPosted: Wed Apr 18, 2012 3:16 pm
by Grizzly
15A round pin plugs are made to BS 546.
They are still manufactured in both insulated and non-insulated pin versions, so either is acceptable.
As Alan says, they should really be used for anything other than stage/event lighting circuits.

Re: Round pin 15amp plugs

PostPosted: Thu Apr 19, 2012 8:53 am
by Matt Macdermott
OK Thanks Alan and Grizzly. I have another problem with testing computer monitors; on some monitors I cannot get a low enough earth bond reading to pass the test despite trying every bit of metal i can see. Do you have any advice please? Is it ok to skip EB and just do insulation etc if there is continuity but it is above the limit?

Re: Round pin 15amp plugs

PostPosted: Thu Apr 19, 2012 11:55 am
by Grizzly
Have a look at the IEE Code of Practice, sections 11.1.3 (page 55) and 11.1.4 (page 56), and see if that might inform your assessment. Ultimately, only the manufacturers will be able to confirm if these scenarios are applicable, but it's a good starting point.

Re: Round pin 15amp plugs

PostPosted: Sun Apr 22, 2012 11:54 am
by safe + sound
''Is this normal or should they all be failed as normal square pin plugs would be?''

Matt have a look at the CoP page 128 paragraph 15. An existing 13A plug without sleeved pins is not a 'fail', just not reusable.

Re: Round pin 15amp plugs

PostPosted: Mon Apr 23, 2012 1:17 pm
by Jim Wallace
Hi Matt

If you don't perform the earth continuity test or are unable to obtain a measured value within the limits specified in the IET CoP but deem the appliance to be safe you need to justify the decision. For example, if a Class I appliance has no accessible conductive parts then an earth continuity test cannot be carried out but you should record this fact. Similarly, if the measured value is above the recommended limit and you consider the appliance to suitable to remain in service then you need to justify why.

Trying to cover all bases....
1. Are you taking into account the resistance of the protective conductor in the power cord when determining the continuity limit? This is sometimes overlooked.

2. Are the accessible metal parts connected to protective earth for safety purposes rather than screening or shielding? This can be difficult to determine as it is usually not obvious. Parts connected to earth for screening or shielding do not have to meet the same requirements as those connected for protective reasons.

It make be a case that you are finding equipment that does not meet the requirements of the IET CoP. This is always a possibility and its best to keep in mind that the purpose of in-service test and inspection is to access the safefy of electrical equipment and not to make it "pass."