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Class 1 appliance with no exposed metal work to connect test lead too
Alex13
24 Posts
Question
Coffee machineOK 3rd problem class one appliance with no exposed metal work to connect test lead too how can I carry out the earth bond test given it is a class 1 appliance and not a class 2 appliance like this Coffee machine
52 Replies
Interesting question. I'd be tempted to look underneath, often there's an exposed screwhead into the metalwork that a test probe can be connected to. I'd be wary about poking any probes THROUGH the casing to touch metal incase it damages something
If its a genuine class I appliance then there will be an exposed conductive part available such as, mentioned, a screw head
It may be poorly or wrongly labelled,
There are cases where class II items of equipment have metals bodies....
Legh
Arran Cameron
432 Posts
A medical physics department in a hospital refers to such devices as plastic class 1. They have this category programmed into their electrical safety testers. It is the same type of test for a class 1 as it measures leakage current from live to earth, but it omits the earth to casing resistance test.

If a plastic class 1 device has a removable mains cable then it's possible to test it as a class 1 by removing the mains cable and carrying out the earth resistance test on just the mains cable, then reconnecting the mains cable to the device for the remainder of the test.
lyledunn
418 Posts
The purpose is to establish if the item is safe rather than filling in a box on a test sheet. 
Alex13
24 Posts
Legh Richardson:
If its a genuine class I appliance then there will be an exposed conductive part available such as, mentioned, a screw head
It may be poorly or wrongly labelled,
There are cases where class II items of equipment have metals bodies....
Legh

Here is hoping soo as otherwise I have little other choice but to fail the item

Alex13
24 Posts
lyledunn:
The purpose is to establish if the item is safe rather than filling in a box on a test sheet. 

That's my point I can't assure that an item is safe if I can't complete a full test run for the item class hence it must be recorded as a faulty item and marked as failed 

Sparkingchip
3370 Posts
😫
gkenyon
1256 Posts
Legh Richardson:
If its a genuine class I appliance then there will be an exposed conductive part available such as, mentioned, a screw head
It may be poorly or wrongly labelled,
There are cases where class II items of equipment have metals bodies....
Legh

That's not necessarily true.

It may only be the motor that's connected in a Class I configuration, for example, either for EMC purposes, or because of static.

There's nothing to stop a manufacturer completely housing a Class I component in insulating material - and either classifying it as Class I, or Class II (if the insulating material meets Class II requirements per the product standard) as they see fit.

If the product is being manufactured in accordance with harmonized standards, there is usually a means of production-line testing the appliance, which would include a test point for the protective earthing circuit. But there's nothing to stop a manufacturer clipping a housing over the top of a tested assembly after the production line test, and I'm guessing that's possibly what might have happened in this instance.

gkenyon
1256 Posts
Alex13:
lyledunn:
The purpose is to establish if the item is safe rather than filling in a box on a test sheet. 

That's my point I can't assure that an item is safe if I can't complete a full test run for the item class hence it must be recorded as a faulty item and marked as failed 

I disagree - just because you are unable to test the appliance, because you don't know how to get at the relevant test points, doesn't mean the appliance has failed - it just means it's not been possible for you to test it.

You can't mark it as "passed" - but I also don't think it's justifiable to mark it as "failed" either, just because the person carrying out the test is unable to carry out that test.

About 30 years ago, I had to deal with something for a distraught person who owned their own carpet cleaning company. A PAT test organisation had failed all of their carpet cleaning machines, because they couldn't get earth continuity to the metal casing of the machines, effectively shutting the business down.

With the particular machine, the bit with all the electrical equipment was inside a removable panel on the larger mechanical housing, and the flexible cable came in through the top through a plastic cover.

So, basically, the outer mechanical housing surrounding the equipment wasn't earthed - but it wasn't an extraneous-conductive-part either and didn't need to be.

So, we correctly tested the machines, and all passed with no problem !


It all depends, though, on what (if any) product standards have been used ... and standards change over time. BS EN 60204-1, for example, would now require the outer "chassis" of that particular machine to be bonded to the PE circuit- but BS EN 60335-series, two particular parts of which would probably apply better to that machine, would have different requirements (if one part were used, it would have to be Class II, but if the other part were used, Class I may be permissible, but no requirement to connect metal parts that are not exposed-conductive-parts to the PE circuit).

"It may only be the motor that's connected in a Class I configuration, for example, either for EMC purposes, or because of static."

I must admit that I have had to find testing points on some rotory floor cleaners that have lots of surface metal but without an obvious PE connect point.
Legh
 
Sparkingchip
3370 Posts
Alex13:
lyledunn:
The purpose is to establish if the item is safe rather than filling in a box on a test sheet. 

That's my point I can't assure that an item is safe if I can't complete a full test run for the item class hence it must be recorded as a faulty item and marked as failed 


So are you are quite prepared to fail brand new equipment straight out of the box from the manufacturer?

Well I think you have to be prepared to take a view and stick your head above the parapet when you think there maybe a problem with an item of equipment.
I was inspecting and testing the local shop's electrical equipment including a couple of newish microwave ovens. Both tested ok on earth bond and insulation, although one had a low imsulation resistance of about 8 MOhms. I made a note on the results sheet that one of the microwaves may fail and sure enough it failed a week later..
Legh
gkenyon
1256 Posts
Agreed ... if you suspect there's something wrong, it's the right thing to do to point it out.

A competent person will always say "I don't know." or "I'm not prepared to decide this for myself." or "I'm personally not happy with that, get it looked into further" etc.
Sparkingchip
3370 Posts
I drove from Worcester to Morecambe to fit an extractor fan and it blew up, I suspect there was a snot of solder on the circuit board, I then had to go to a couple of wholesalers to get another one and swap it over, when I should have been on my way home.

I always like to have two of most things on my van, I don’t know how guys cope buying exactly what they think they will need.
Alex13
24 Posts
Sparkingchip:
Alex13:
lyledunn:
The purpose is to establish if the item is safe rather than filling in a box on a test sheet. 

That's my point I can't assure that an item is safe if I can't complete a full test run for the item class hence it must be recorded as a faulty item and marked as failed 


So are you are quite prepared to fail brand new equipment straight out of the box from the manufacturer?

Yes if I'm putting my name to the safety of an item is it not better to fail an item than pass it wrongly and have someone die then your held in cort on a charge of manslaughter for the death due to negligence on your part no thank you I put no price on life 

Alex13
24 Posts
gkenyon:
Agreed ... if you suspect there's something wrong, it's the right thing to do to point it out.

A competent person will always say "I don't know." or "I'm not prepared to decide this for myself." or "I'm personally not happy with that, get it looked into further" etc.

Thank you excatly right if something is in use its a little different but still best to keep an eye on it I'm working for a charity shop so items are in the main for resale therefore the must be right otherwise they fail its as black and white as that no gray area

Sparkingchip
3370 Posts
Okay, so you’re testing in a charity shop to ensure appliances are fit for resale, so it doesn’t really matter if you say something should be scrapped does it?

If you start testing in a location where there is specialist equipment and appliances it will be a completely different ball game as they cannot just be thrown away.

So you will either have to make the decision that the appliances are safe or recommend that advice is sort from the appliance manufacturer.

i can’t be asked to get the Code of Practice out at this time on a Saturday night, but I’m sure there are recommendations in there and it was something we discussed whilst training as an electrician and on the PAT course that there are all insulated class 1 appliances such as some laptop power supplies.

Try this one, how are you going to PAT a Teflon coated electric iron or are you going to scrap them all?
Alex13
24 Posts
Sparkingchip:
Okay, so you’re testing in a charity shop to ensure appliances are fit for resale, so it doesn’t really matter if you say something should be scrapped does it?

If you start testing in a location where there is specialist equipment and appliances it will be a completely different ball game as they cannot just be thrown away.

So you will either have to make the decision that the appliances are safe or recommend that advice is sort from the appliance manufacturer.

i can’t be asked to get the Code of Practice out at this time on a Saturday night, but I’m sure there are recommendations in there and it was something we discussed whilst training as an electrician and on the PAT course that there are all insulated class 1 appliances such as some laptop power supplies.

Try this one, how are you going to PAT a Teflon coated electric iron or are you going to scrap them all?

Well I was trained and qualified under the 4th edition so this wasn't covered and yes I'm certified by the iet as a pat tester and in the case of those items same as these I spoke to the boss who agreed that they must fail if they can't be properly tested also I have yet to come across such a coating causing a problem with the test (I have all ready tested and passed 10 different sandwich presses with non stick Teflon coatings with no issues, want get smart Alec let's get smart Alec it's my first name (Alexander, my grandad was known as Alec I was named after him) but any info from the code of practice I may have missed would be most helpful

Sparkingchip
3370 Posts
I recently stood in a Home in Multiple Occupation looking at a Teflon coated iron that needed PAT that had been purchased within the last year, since I last did the PAT, and entering onto the appliance log a copy of which had to be submitted to the Local Council Housing Team so the HMO licence could be renewed.

So how do you PAT a virtually new Teflon coated iron?

https://medium.com/@ironsexpert/steam-iron-soleplate-types-ceramic-stainless-titanium-62c60efefe7c
Sparkingchip
3370 Posts
The IET PAT Guide- Code of practice for in-service inspection and testing of electrical equipment covers the subject of electric iron construction in some depth, indeed there are four illustrations of different types of construction.
Sparkingchip
3370 Posts
Sparkingchip
3370 Posts
Sparkingchip
3370 Posts
Sparkingchip
3370 Posts
So are you going to throw away the irons with unearthed metalwork on them or Teflon coated sole plates, because you cannot get a test result?
Alex13
24 Posts
Sparkingchip:
So are you going to throw away the irons with unearthed metalwork on them or Teflon coated sole plates, because you cannot get a test result?

Ahh you see there in lies a problem if the sole plate is metal un earthed the body plastic and both basic and re-enforced insulation are used the item labeled class 2 even with an earth then its class 2 the problem with these coffee machines is the have no class two marking therefore must be treated as class one (as per the code of practice) but with no exposed metal work let alone earthed exposed metal work then surely they fail an earth bond test after all the test covers only parts a user may come into contact with during use (so any internal earthed metal work sufficiently protected by insulation requirements is therefore protected against contact by the user in the event of a fault developing meaning it can't be used as a eath bond test point due to the need to deconstruct the item to access it therefore it would invalidate any test results gained 

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