Disco Lights Pat Testing

[Kainthirteen]

Hello everyone

Ive recently done my first pat test on a local disco, which was quite the learning curve.

But in the end i got through it and i am happy with my results, except with some disco lights

i am using a battpat as my trainer said it was good for basic work as i mainly want to do some offices

but with these disco lights i assumed they were class 1 as i could not find a class 2 symbol

now other then the stand it is made entirely of plastic, but the plastic is held together with black painted metal screws, so i first thought to test it as a class 1 metal and attach the probe to the screws but every screw came back as a fail for earth continuity and a pass for insulation.

i also have a class 1 plastic button which just did the insulation test

am i overthinking this? there was 2 of them and they were in good condition and he kept them in the original packaging.

In the end i passed them as class 1 plastic, as i thought it was less likely they both failed the same way.

DMX512 127 RGB LED Effect Light Stage Lighting Disco DJ Party Show AC90-240V EU Plug

Here is a link to a similar type, only differences is my customer uses a kettle lead for his and the innards is mostly made of plastic

Hopefully i can get some clarification

Many thanks

 

[davesparks]

A battery powered tester cannot source enough test current to carry out the earth test of test class 1 equipment or IEC leads properly.

How can an entirely plastic item be class 1, unless the definition of class one has changed from being equipment with earthed metal casing?

You cannot decide the class by the test results alone, a class 1 item with a broken earth connection will give the same results as a metal cases class 2 item.

The IEC leads should be tested as an item in their own right, not just as part of the item they are supplying.

 

[Kainthirteen]

Hello Dave

Thanks for the reply

I had done all the IEC Leads separately

From what i understood of the course i took, there was 2 kinds of class 1, Metal and Plastic, as class 1 needed to be earthed, and as this device required a IEC lead i determined it needed to be earthed. (And it was drummed into me if no class 2 Symbol then treat as class 1)
So it had to be class 1, but i don't believe the screws or metal stand is attached to the lighting parts, so there was nowhere for me to test earth continuity.
Ive done some more reading around sites for examples and the few with plastic examples say to test only Insulation Resistance and note down that a earth continuity could not be performed.

Hoping for some more clarification

Many thanks

 

[Farmelectrics]

Do a visual and put a sticker on them lol

 

[Richard Burns]

Class I is something that must have an earth in order to avoid the risk of electric shock because there are parts that may be come live in the case of a fault. However these "live" parts do not always seem to be accessible at all so it does seem that there are items that are Class I that have no risk of electric shock, which does seem a contradiction, however it may be that the casing is not sufficiently robust to class as reinforced insulation and so requires an earth even thought he parts that may become live are behind the case.

This is just me thinking about it and not any sort of authoritative statement.

I have had items where I have taken them apart to find the earth to test continuity, hardly conducive to a cost effective PAT test!
For the lights it could be that the lamp holders present a potentially live metal risk whilst changing the lamp?

 

[davesparks]

Do a visual and put a sticker on them lol

If he's using a battery powered tester then he might as well be doing that!

 

[Deleted member 72666]

Class I is something that must have an earth in order to avoid the risk of electric shock because there are parts that may be come live in the case of a fault. However these "live" parts do not always seem to be accessible at all so it does seem that there are items that are Class I that have no risk of electric shock, which does seem a contradiction, however it may be that the casing is not sufficiently robust to class as reinforced insulation and so requires an earth even thought he parts that may become live are behind the case.

This is just me thinking about it and not any sort of authoritative statement.

I have had items where I have taken them apart to find the earth to test continuity, hardly conducive to a cost effective PAT test!
For the lights it could be that the lamp holders present a potentially live metal risk whilst changing the lamp?

I totally agree and have done it myself, with the added benefit of leaving site with peace of mind which is worth the extra time invested.

 

[Farmelectrics]

I'm convinced this pat testing is a ticket exercise anyway

 

[Flanders]

A lot of desk fans are class 1 but without taking tbe thing apart you will struggle to get a earth connection , i was told by a so called pat test intuctor that with items like this to test them as a class 2 equipment , pointless in my view

 

[lennox]

What's the problem in having a battery tester? Aren't most multi meters battery!!??

 

[Lucien Nunes]

If the lights have DMX or audio connectors, then the internal electronics of the unit may be electrically accessible to the touch via any cable connected to those. I.e. although it might be impossible to get a shock from the plastic casing, the earth connection might be required to prevent the pins of an XLR connected to the DMX input becoming live in the event of a fault, perhaps making interconnected pieces of class II equipment live as well.

If I suspect this situation exists, I do a low current / multimeter test between the mains earth and signal ground, e.g. pin 1 of a DMX XLR. If there is continuity, it does not prove that it is completely sound or that it is even necessary, but at least I know the green/yellow wire is probably still attached inside. NEVER run a high current continuity test in this scenario as you will probably just blow the tracks off the PCB.

 

[Flanders]

If he's using a battery powered tester then he might as well be doing that!

Please explain as mft are battery operated and a of pat tester are so why do you think they are not to the job

 

[Lucien Nunes]

Full-spec testers can apply a heavy-current test for earth continuity, usually 25A, to locate connections that are still of low resistance but mechanically loose or fatigued e.g. where a flex weakens with use at the entry point or a ring terminal is slack under its screw. Faults of this kind are more common on equipment that is regularly moved than on fixed wiring. If the connection is hanging on by a few strands the 25A test will show it up while a multimeter or MFT test will not. Battery testers cannot deliver this test for obvious reasons.

 

[davesparks]

What's the problem in having a battery tester? Aren't most multi meters battery!!??

Yes multimeters are battery powered and they are capable of carrying out all of the tests required of them so they are fine.
A portable appliance tester however needs to be able to carry out a high current bond test to properly test the earthing of class 1 equipment, this can't be done by battery testers.

 

[HandySparks]

Yes multimeters are battery powered and they are capable of carrying out all of the tests required of them so they are fine.
A portable appliance tester however needs to be able to carry out a high current bond test to properly test the earthing of class 1 equipment, this can't be done by battery testers.

Except this one:
Transmille 5080 PAT Tester - Battery Powered and Downloadable 5080 PAT from Transmille

 

[Lucien Nunes]

Interesting, haven't seen that before, I stand corrected.

 

[davesparks]

That'll be the exception that proves the rule then!
I've not seen a battery tester that can manage that until you get into the realms of microohmeters/ducters etc

 

[Arundel/Lx]

What's the problem in having a battery tester? Aren't most multi meters battery!!??

Yes, multimeters are battery but the test current they produce is in the order of milliamps.
An earth test is carried out at either 100 to 200 milliamps or 10 to 25 Amps.
The latter being the usual test current for heaters, kettles etc.
A battery in a multimeter would not have the power to produce thsr sort of current.
Hope this helps.