PAT failing on every toaster?

[GallyMO]

Hi. As Maintenance Officer of a holiday complex, I have been issued a new Martindale HPAT 500 to do routine testing with. All seems OK except every toaster in the entire place fails the earth continuity test showing >20Ω I'm holding the lever down to create 'on' position. Doesn't seem likely every toaster in the place has failed at the same time, eh? Something not right?!

 

[DPG]

Are they class I? Where is your earth clip connected to?

And welcome to the forum!

 

[GallyMO]

Are they class I? Where is your earth clip connected to?

And welcome to the forum!

Definitely no Class 2 symbol anywhere so assuming class 1. Have tried clip on various places - grips that hold the bread in place/ divider between slots. I did wonder if they could be Class 2?
And thanks, definitely just allrounder looking for pro advice!

 

[DPG]

What's the make and model?

What reading do you get if you measure resistance (just with a multimeter, not at high current) between the earth pin of the mains plug and any exposed metalwork?

 

[westward10]

I have never seen a Class II toaster are they all the same type.

 

[GallyMO]

What's the make and model?

What reading do you get if you measure resistance (just with a multimeter, not at high current) between the earth pin of the mains plug and any exposed metalwork?

they are various ones, mostly from John Lewis I think! I will try that tomorrow.

 

[DPG]

they are various ones, mostly from John Lewis I think! I will try that tomorrow.

Check for the double square icon on each of them if they are different.

Keep us posted.

 

[GallyMO]

I have never seen a Class II toaster are they all the same type.

No, they are all different, I think they have bought them all from John Lewis, but different models depending on the size of the units, but its a bit annoying because they don't like all the same things across the units, they like them all to look different. This is why I thought its a bit odd they all fail.

 

[James]

long time since i have done any pat testing but I always used to take the top off the plug to check fuse rating.
you can then see if there is an earth wire.
Note: i expect that many will have a moulded plug so you cant see now days.

I think you need to examine the toasters a bit more thoroughly and see what part may give you a god earth test point, maybe a screw on the bottom?
I would expect that the metal grid that covers the elements would be well bonded to earth though.

As above, try a multi meter to see what is giving any continuity to the earth pin.

 

[Rockingit]

I'd suspect that it's as simple as that you're not managing to get a good enough connection due to laquer etc. If you had a proper insulation tester that could put some balls into it then you'd get a different result. Or..... they're actually class 2 after all and not marked - sacrifice the plug off of one and see if it's 2c flex.

 

[Moley]

Looks like it's time to get your tools out(!) First off, what shape is the cable. Is it round or flat? Flat would suggest 2 core so double insulated. If it's a non moulded plug the pull out a screwdriver, open the plug and see if there's a connection to the earth pin. If there's not then it's class 2. If it's a moulded plug then take a good look at the toaster. Look at where the cable enters. You need to take off the base/side/whatever to get access to where the cable comes in even if it means sacrificing one of the toasters. You need to access the cable connections direct. Once you have got at the connections then re-test with your earth probe direct on the earth wire. If that passes then trace all connections to that earth and re-test at various points until you find where the high reading is.

BTW, tell the company you work for to throw away that tester and get one that does a proper earth bond at a minimum of 10A, preferably 25A. The Martindale does an earth bond at 200mA. If there's a break in the earth cable with just a few strands remaining then at 200mA it'll pass but if there was an earth fault on the unit then those strands could easily melt away leaving the unit unearthed. A good 25A earth bond will show up faults like that straight away. I really don't know why low current earth bond tests are allowed.

 

[DPG]

Looks like it's time to get your tools out(!) First off, what shape is the cable. Is it round or flat? Flat would suggest 2 core so double insulated. If it's a non moulded plug the pull out a screwdriver, open the plug and see if there's a connection to the earth pin. If there's not then it's class 2. If it's a moulded plug then take a good look at the toaster. Look at where the cable enters. You need to take off the base/side/whatever to get access to where the cable comes in even if it means sacrificing one of the toasters. You need to access the cable connections direct. Once you have got at the connections then re-test with your earth probe direct on the earth wire. If that passes then trace all connections to that earth and re-test at various points until you find where the high reading is.

BTW, tell the company you work for to throw away that tester and get one that does a proper earth bond at a minimum of 10A, preferably 25A. The Martindale does an earth bond at 200mA. If there's a break in the earth cable with just a few strands remaining then at 200mA it'll pass but if there was an earth fault on the unit then those strands could easily melt away leaving the unit unearthed. A good 25A earth bond will show up faults like that straight away. I really don't know why low current earth bond tests are allowed.

Initially the the low current earth bond tests were mainly used for IT/office equipment, which is fine. But it does seem more common now for people to use this test on things that really ought to have a higher current test.

 

[Intoelectrics]

I think you have to look at what is consistent. Its very extremely unlikely that all the toasters are faulty, and if they are of differing makes then also unlikely they are all class 2. So personally i'd be either looking at the functionality of the tester or an error by the user, as first port of call.

 

[Lucien Nunes]

Some cooking equipment gets coated with an insulating film of grease that evaporates from the food and gets burnt on. You need a sharp probe and plenty of pressure. The moving grilles of toasters are probably not effectively earthed,, nor external chromed bezels and crumb trays. You might have to get deep inside with the probe to the actual chassis.

 

[WallaceP]

Hi. As Maintenance Officer of a holiday complex, I have been issued a new Martindale HPAT 500 to do routine testing with. All seems OK except every toaster in the entire place fails the earth continuity test showing >20Ω I'm holding the lever down to create 'on' position. Doesn't seem likely every toaster in the place has failed at the same time, eh? Something not right?!

I am not sure why you would need to hold the lever down to test the earth connection?