PAT Test

loadz

Hi
Does anyone know about PAT testing. I have a couple of questions on it as i have just started doing it at work.

1 If there is no class rating on an appliance do you test it as a class 1 or a class 2.

2 One appliance (a sweet manhine) had no class rating on it so i tested it as a class 2 which means double insulated and it failed the substitute leakage current test. I then tested it as a class 1 and it failed the bond test.Maybe the paint on it isn't helping the earth lead or maybe there actually is a fault with the appliance , I'm not sure. Does anyone have experience of this please.

M cebee

im not familiar with 'pat' testing

i assume it's class 1 if it's earthed and should pass the 'bond test' to the chassis proper

some of the class 2 appliances(non-earthed) like dvd players have a metal case but would fail a bond test

loadz

Its not to be assumed its class 1 because it has an earth lead it says in the instruction book for the tester. The machine is just after coming in to us from somewhere else and there is a tested label dated last week on the appliance so i don't know what test they did or did they just put a tested label on it.

M cebee

it should be safe to assume class 1 where there's a protective earth in use.

class2 is normally marked and is 2-wire

there aren't too many variables

you're not testing earth continuity through painted metal are you?

davelerave

10-10-20

It's covered better here in Wikipedia than it is on the PAT-test homepage.
http://en.wikipedia.org/wiki/PAT_Testing

Class I - Single insulated wiring, which requires an earth connection. There is no symbol for a Class I product so if a rating plate has no symbol on it then it is usually Class I.

Class II - Double insulated wiring, therefore no need for a earth lead. Class II is indicated by double box.

Class III - These are appliances that are supplied at a low voltage (usually called Safety Extra Low Voltage) which must be less than 50V. These appliances are supplied with a transformer supply that is also marked.

My understanding is:
Any device with exposed parts of the metal chassis, must have an earth unless classed as a double-insulated device.
Either open the chassis and connect the flying earth lead to a bare metal section and test again.
If it still fails, identify the earth-to-chassis bond point, test it with a multimeter, etc... You may just have selected an unbonded panel.

loadz

If it is class 1 you would think that the metal side panels would be earthed as they are directly on to the frame. If its not earthed then the supplier should come and repair it or certify it because i'm not signing it off or opening it up to repair it as i then will get the usual stuff like you shouldn't have opened it and all that.