PAT testing LED

[android12]

Hi does anyone know the procedure for pat testing a 600 x 600 led light fitting with electronic ballasts and transformers, Is this classed as sensitive equipment also metal casing so class 1, any help much appreciated

[Shez]

Just because it's a metal casing doesn't mean it's class 1. The presence of the double insulation symbol or the use of two pole mains connectors will give you a more definitive answer.

[android12]

I was more concerned about damaging the led modules or the ballast, the casing's fine if class 1 or 2

[JimWebber]

I was more concerned about damaging the led modules or the ballast, the casing's fine if class 1 or 2

 

 

Personally speaking, I would be most concerned about introducing a high-voltage "Megger" style test near anything electronic...

 

Maybe I am a bit old school on this one - I wouldn't be surprised if modern equipment wasn't a little more robust.

 

Personally speaking, as far as testing goes, I would be satisfied that due dilligence was taken if there was a good visual inspection, followed by an earth bond test (if Class 1) and maybe a leakage test.?

 

Jim

[Brian]

1) Any kit being sold must be CE marked.

2) To be CE marked it must conform to standards.

3) The standard in this case is likely to be EN60065.

4) EN60065 calls for routine testing during manufacture which comprises...

a) a 10A Earth Bond test

b) a 2kV flash test for Class 1, 3.5kV for Class 2.

 

Now, for In-Service Testing you're not required to do a flash test but there is no reason kit shouldn't pass a 500v DC leakage test. The CoP exempts doing this test on kit which is not to standard but, as I point out above, there is no reason for the situation to exist on modern kit.

 

You are, of course, perfectly entitled to use you education, training and experience to reach a different conclusion.

[bigclive]

If an electronic appliance of any description isn't capable of dealing with a 500V insulation test then it is not suitable for connection to the mains supply which can see transients that exceed that.

 

Why should we pussy-treat PC's and other electronic equipment when it's actually the manufacturers responsibility to make it compliant in the first place.

[dbuckley]

Many items of electronic equipment have 250V MOVs from L and N to earth, and (at best) these invalidate a 500V megger test.

 

My opinion is to treat as IT equipment, use 250V insulation test. Thus if my tester shows ">500MΩ" insulation and earth bond is well under an ohm I smile and sign.

 

By New Zealand regs (and thus presumably many other countries regs) certain classifications of equipment are considered acceptable with a 250V insulation rating of as little as 1MΩ or greater.

[bigclive]

Yeah, they should really do something about those MOV's. I'm not convinced that having them between live and earth (or even capacitors for that matter) is a good idea at all. Ground should be kept isolated completely and not used as a circuit connection for components that can leak current or fail short circuit. The 250V test is testing at below peak mains voltage of around 330V so it's not even representative of normal operation.

[Don Allen]

When an appliance is PAT tested (one of life's many odd things, saying two tests i.e. Portable Appliance Testing tested ) the active and neutral wires are connected together and the insulation test voltage of 500V which is usually the default voltage on a lot of testers, is applied between the active and neutral wires that have been connected together and the earth wire. Please note that there is no potential difference between the active and neutral wires so the voltage applied to the appliance electronics is 0V.

 

So you cannot damage a sensitive appliance's electronics by doing an insulation test.

 

What you can damage are the MOV's and X2 mains rated suppression capacitors that may be across active and or neutral and ground.

 

A competent PAT tester will look for what equipment has this protection and change the test voltage to 250V, as each test of 500V causes stress to the suppression devices.

 

You can find out a lot on PAT testing by going to the electrical forum, but this post belongs in lighting so browsers can be informed.

 

The insulation test is the second test on this

[Brian]

... X2 mains rated suppression capacitors that may be across active and or neutral and ground.

 

You mean Y capacitors. The X capacitors go between L and N.

 

 

[E2A]

 

A 500V DC test voltage should not, and indeed must not, cause damage to any X or Y capacitors.

 

To meet the relevant safety standards an X2 capacitor must be able to stand a DC test voltage of 2kV for 2 seconds. A Y2 capacitor must stand 4kV for 2 seconds.

 

If manufacturers use capacitors that won't stand 500V then I'd much rather find out when testing than when the capacitor fails and kills someone. Remember that a faulty X capacitor increases the risk of fire; a faulty Y capacitor increases the risk of an electric shock.

 

 

Normal mains has a peak voltage around 360V. Why then would you test equipment at only 250V?

[grizzly]

Normal mains has a peak voltage around 360V. Why then would you test equipment at only 250V?

 

As dbuckley touches on above, if you've got equipment fitted with MOVs, which may well start conducting below 500V, they are going to give a reduced reading on the 500V IR test, or even a fail.

If you test them at 250V, then you are getting a meaningful reading for the actual resistance of the insulation between live parts and earth, rather than a false reading from the MOVs.

That is the reason the 250V IR test was introduced in the first place.

 

 

 

[Brian]

That is the reason the 250V IR test was introduced in the first place.

 

No, the 250v test is intended for equipment that does not comply with current safety standards.

 

As I pointed out above, all equipment of the type we are discussing sold for at least the last 10 years MUST comply with EN60065 or, if it's IT equipment, EN60950 and equipment designed to these standards will stand the 500v test.

 

If anyone disagrees with that assertion then please post some hard evidence.

[grizzly]

 

No, the 250v test is intended for equipment that does not comply with current safety standards...

 

If anyone disagrees with that assertion then please post some hard evidence.

 

 

Article isn't on the Engineering Talk website anymore, but I tracked it down with the Wayback machine:

http://web.archive.org/web/20091113121837/http://www.engineeringtalk.com/news/saw/saw213.html

 

 

 

[Brian]

The new IEE code recognises that testing insulation resistance at 500V DC might be problematic in some circumstances ...

 

In some cases, sensitive electronic devices and particularly older IT equipment which does not comply with BS EN60950 may be damaged by 500V.

 

However, in practice, this may not be a significant issue as BSEN 60950 has been around a lot longer than most IT equipment currently in common use.

 

My bold.

[Don Allen]

Jands Technical Bulletin TNJLT104 - Testing and Tagging of dimmers

Connect one probe of an insulation resistance meter (megger) to the earth pin on the

input connector and the other probe of the meter is connected to the live conductors

electrically shorted together. A nominal measuring voltage of 500V d.c. shall be used

and a resistance of 1M Ohms or greater should be expected. The exception to this

will be the HUB, HP and HPX series of dimmers, which will have a resistance of

around 47k Ohms for the HUB and HPX series units and 16k Ohms for the HP

series. This is due to monitoring circuitry between the Neutral and Earth Conductors.

 

If I test these dimmers at 500V they fail, at 250V they pass.