SimplyPats User Forum

Hi folks,
Bit of background info first, My employer put me through the c&g pat test course about 6 months ago, he's recently bought a megger pat420, which is great, but the downside is I am from a non electrical background. I have some questions about testing 110v tools and I would love it if someone could help me out a little
1) I have 3 class 1 tools (110v) but I cannot find an earth point to complete the EB test, 1 item is totally encased in plastic, the others have some metal casing but none get an earth reading whilst doing the EB test, is it ok for me to skip the EB test and carry on with the rest of the tests?
We were told on the course that if it wasn't possible to get an EB reading then make a note of it and carry on - I would just like some confirmation on this.

2) On the pat420 when testing any 110v appliance it skips the load diff test and the load test, it says it's not available and skips the tests but passes the appliance, these tests run fine with 240v appliances and I'm just wondering if this is normal?

3) My employer is looking me to make up some extension leads, we have some 2.5mm cable which we use on 32a plugs, but he wants me to use the same cable for 16a plugs.
Would this be safe to use? In theory it should only be using the power from 16a 110v appliances but surely using a bigger cable means there's more room for issues to occur should tools draw more power

I do appreciate any info you guys provide and I do apologise for my ignorance.
Many thanks,
Luke

I'll have a go at answering some of these...



Yes, that's quite correct.
There are certain times when you won't get an earth bond reading from Class I appliances.
Obviously, ones fully encased in insulation, although I would see if you are able to remove any covers to (safely) get a continuity reading.
A multimeter is useful to show the presence of earth continuity, without having to run the EB test on the PAT machine every time.

As for your other 2 tools with metal casing, there can certainly be methods of Class I construction that have unearthed metal present.
Have a look in the IET Code of Practice (which you should have if you've taken and passed C&G 2377).
Sections 11.1.3 (p73) and 11.1.4 (p74) should illustrate this perfectly:

11.1.3 Class I construction incorporating unearthed metal separated from live parts by basic and supplementary insulation
11.1.4 Class I construction incorporating unearthed metal separated from live parts by basic and earthed metal



Sorry, no experience with the PAT420



2.5mm cable is perfectly fine to be using with 16A plugs, as it has a current-carrying capacity of 20A.
You really shouldn't be using it for 32A connectors, as it obviously cannot safely carry any current above 20A!
You might get away with 4mm for 32A extension lead lengths under 20m, but really you should be using 6mm cable.
Overheating, melting insulation, fire, short circuits, electric shock: all risks leading from using undersized cable.

You need to rethink this...

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C&G 2377-01 & -02