Pat Testing Cable

[Stig]

It is that time of the year when the PAT tester comes out of its box and gets a battering for three weeks. The problem I have is Socapex cable and electroflex. Does anyone know of an easy way of testing these types of cable that is not to time consuming. Or is there some clever little gizmo that does all the work for you.

 

Please help as my sanity is hanging on by a thread!!!!!!! :o

[Brian]

Hmm, to do a 'proper' test on a 18-core multi you need to do 6 full tests and 153 insulation tests. Time to build a jig I guess. Though where you get 18-way rotary switches which will do mains is anybodies guess. The other way would be to make something using 4mm banaplugs.

[Ike]

153 insulation tests

could you not do insulation tests between conductors;

1 and 2

then bind 1 and 2 together and test between (1 and 2) and 3

then (1,2 and 3) and 4

(1,2,3 and 4) and 5 etc

 

thus requiring only 17 tests?

[Brian]

could you not do insulation tests between conductors;....

Hmmm, interesting idea. Makes the test jig a bit more complex.

 

Scrub that, the test jig could actually be quite simple; one panel socapex and 17 toggle switches.

 

PS

Note to self, stop starting replies with 'hmm'

[Tomo]

Did you never do error collapsing at school then Brian?

 

The only possible problem with this method is that it reduces the resistance of the insulation as it all ends up parallel, and will change the capacitance.

Makes it a harsher test actually, which is good although sometimes more expensive.

 

Won't be serious with PAT testing as you're looking at breakdown voltages (IIRC), which doesn't change with parallel obviously.

[Brian]

Did you never do error collapsing at school then Brian?

Nope.

it all ends up parallel

I thought about that; the PAT test needed is the insulation test which takes place with 500 volts DC across the UUT and expects 2 MOhms miniumum as a result. Since the test is DC you can neglect the capacitance. I had a quick look but couldn't find any figures for a cables insulation and, since it's raining outside, I'm not going to get a cable and measure it.

 

A problem is that the results obtained will depend on a cable's lay-up. Testing between two cores which are physically next to each other in a cable will test the insulation value of two thicknesses of insulation plus any gaps between them and how closely they touch. Testing between two cores which lay opposite each other on the 'outside' of the lay-up will go via the intermeadiate cores and that will depend on whether they float or are grounded.

[robloxley]

We find that a Megger (500V insulation tester) is a more user-friendly bit of kit for testing socapex and heavy mains than a standard PAT tester (which is expecting you to be testing an appliance).

[MarcT]

Ok then folks - a some questions for you:

 

1) Are there any rules/regulations/guidelines about the testing of cables (TRS, Heavy Mains & Socapex), or is it simply a visual inspection (cable & connectors), continuity & insulation tests? What test documentation, if any, is necessary? (eg is a dated TESTED sticker sufficient?)

 

2) Can anyone recommend a good PAT tester for the usual type of theatre applications, which must include an "IT equipment" test (for those items which cannot be flash tested)? Do any offer a cable testing facility?

 

Thanks & Regards,

[Brian]

Are there any rules/regulations/guidelines about the testing of cables

Yes, you could do worse than getting hold of the ABTT code of practice.

What test documentation, if any, is necessary?

You would be wise to treat a cable as any other piece of kit and have a log entry for it. So much easier to prove you'd tested it.

flash tested

Do you mean flash test, which is normally done at up to 5kV, or do you mean the normal 500V insulation test.

I personally have a Seaward IT1000 which I get on OK with.

Do any offer a cable testing facility

Some have extension lead test sockets built in, though none have 15A so you'll still need an adaptor.

[Andrew C]

(for those items which cannot be flash tested)? Do any offer a cable testing facility?

Practically nobody in a theatre will need "Flash Test" facilities.

 

I use a Robin PAT 500, seems no more boring than any other. You can create your own test code, which helps. (ie Theatre lanterns with the ABTTs recommended pass/fail levels)

 

The Robin software for record keeping is grim, I use Safety 1st which is OK but ££.

[MarcT]

Firstly thanks Brian & Andrew for the advice and suggestions. I'm looking for an easy to use, inexpensive tester with the most functionality, but will probably only get two out of those three...

 

flash tested

Do you mean flash test, which is normally done at up to 5kV, or do you mean the normal 500V insulation test.

Nope - I mean a "flash test" as offered by a number of PAT testers currently on the market. Eg from the range carried by RS, the Robin Smart PAT 5000, Edgcumbe Micro PAT+ & D2112, Seaward PAT 2000i, 1000X, 1000S & Supernova, Megger PAT2 & PAT4DVF all have a "flash test".

 

Typically this involves a 1.5kV (AC) test for Class 1 (ie earthed) appliances, with the test voltage being applied between the earth pin, and the live & netural bonded together.

 

For a Class 2 appliance (double insulated / single reinforced insulation) a 3kV test may be used, with an external clip or probe in contact with the appliance body.

 

I'm well aware that such a test has the potential[*] to damage sensitive equipment, (in particular older equipment which may have RFI suppression capacitors rated at 1500V) for but for incandescent luminaires and extension leads an annual flash test may be appropriate.

 

Anyway, it just goes to show that not all PAT testers are created equally.

 

Thanks & Regards,

Marc

 

[*] Warning: Poor Pun... :)

[Andrew C]

My point about flash testing is that it stresses the insulation, and would only normally be used as a final inspection procedure during manufacture, or in exceptional circumstances. It would not be used in a regular "PAT routine".

 

Yes, many testers offer it, but most of us don't need it.

[gareth]

Indeed, flash testing can be highly undesirable in many circumstances - any sort of electronic equipment is highly susceptible to damage if subjected to a flash test.

 

For ordinary run-of-the-mill flash testing of typical theatre lighting and sound equipment, flash testing is unnecessary. All that's required is a thorough visual inspection, insulation test, earth bond test, and an operational test (i.e. does it actually work when you plug it in?!).

[Andrew C]

For ordinary run-of-the-mill flash testing of typical theatre lighting and sound equipment, flash testing is unnecessary.

 

For ordinary run-of-the-mill PAT testing?

 

Thanks for the opportunity to make "the ton"!! :)

[Brian]

For ordinary run-of-the-mill PAT testing?

Indeed. Flash testing is considered an optional test. To quote from a 'how to' book I have...

 

'the flash test should only be carried out by fully trained personnel, preferably under workshop conditions.'

'Generally this test is only performed when an appliance has been into the workshop for repair...'

'Take care when performing a flash test...It is best to have a second person on hand so that if you receive a shock they can remove the power and resusitate you.'