Class 1 Equipment

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Class 1 Equipment

Postby Derek » Mon Mar 07, 2011 11:11 am

Hi

Having some bother passing class 1 equipment in particular a desk fan. I cannot get it to pass the earth bond >19.99 ohms.

The trouble is i cannot get a "good earth" on the appliance ,all the metal work screws etc are not sufficient. Do i have to then strip it down to get to the insides of it to get a good bit of metal ? (lead length about 2m so its not the resistance thats failing)

Thanks for your reply

Derek
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Re: Class 1 Equipment

Postby PATman » Mon Mar 07, 2011 3:48 pm

Hi,

If you look on the Seaward website FAQ's you will find the answer there, basically they advise:
If earthed metal parts are not accessible they cannot be continuity tested. Make a note on the test record that the appliance is Class I but has no accessible earthed metal parts and as such an earth continuity test cannot be performed.
Hope this helps

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Re: Class 1 Equipment

Postby LeeTurtle » Tue Mar 08, 2011 9:23 pm

Hi

Also check out page 73 (I think?, not got one to hand at this min) of the Code Of Practice, the notes at the bottom will also give you further guidance.
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Re: Class 1 Equipment

Postby LeeTurtle » Thu Mar 10, 2011 11:38 am

Hi

Page 74 (not 73) of the COP in the notes at the bottom of the page goes on to explain about casual or fortuitous contact.

Hope this helps.
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Re: Class 1 Equipment

Postby visionary » Wed Jul 13, 2011 6:29 pm

Quote by PATman "If you look on the Seaward website FAQ's you will find the answer there, basically they advise:
If earthed metal parts are not accessible they cannot be continuity tested. Make a note on the test record that the appliance is Class I but has no accessible earthed metal parts and as such an earth continuity test cannot be performed"

With this in mind and thinking of external PSU for for example computer monitors which are by definition class 1 but do not have any external metal or earthing points, whilst making a note on the test record that no accessible earthed parts are available and cannot do continuity test, would you then do a class 2 test on the item instead or just leave it as a failed class 1?
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Re: Class 1 Equipment

Postby PATconstructive » Wed Jul 20, 2011 5:07 pm

Whilst I do not disagree with the comments made above, I have tested quite a large number of Class 1 fans both desk and pedestal type. What I do is disassemble the fan slightly ie. remove the safety cage (most are by means of hinged clips and maybe one tiny nut and screw) and then remove the plastic fan blade from the motor shaft (usually the retainer is a plastic hub with a left hand thread). In all but a couple of unusual cases a satisfactory earth reading has been made by putting my earth clip onto the motor shaft itself. Re-assemble to conclude. On a couple of occasions dis-assembly revealed broken housings which were not apparent upon initial inspection.
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Re: Class 1 Equipment

Postby Jim Wallace » Wed Jul 20, 2011 5:26 pm

The guidance in the CoP is that "The continuity test should be made between accessible earthed metal parts and the earth pin of the plug." This is why we recommend that in the event that there no accessible parts then this should be noted.

Another way to view this is that the reason accessible metal parts are earthed is to provide protection against electric shock in the event of a failure in the basic insulation. If the part in question is not accessible there is no risk of electric shock.
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Re: Class 1 Equipment

Postby PATconstructive » Wed Jul 20, 2011 6:03 pm

I hear what you are saying Jim and stated I do not disagree with the previous comments. However I also take a view that this product has been designed with removable safety covers and parts for purposes of cleaning etc. These covers can often be removed by operatives with no tools required (some may inadvertently leave the item plugged in whilst cleaning). I suspect because this is possible is the same reason the manufacturer retains the Class 1 status. i.e the metal parts can become exposed under normal maintenance conditions.
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Re: Class 1 Equipment

Postby edutech » Thu Sep 08, 2011 5:06 pm

Add an extension to the probe so that you can touch the spindle through the cage. A large straightened paper clip does the job nicely.
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Re: Class 1 Equipment

Postby LeeTurtle » Thu Sep 15, 2011 3:03 pm

edutech wrote:Add an extension to the probe so that you can touch the spindle through the cage. A large straightened paper clip does the job nicely.


!!!!? :o

What happened to the BS finger!!
I totally agree with jim, if you can't get a good reading, it maybe has a fortuitous contact, it doesn't necessarily mean it's a failure. However by removing guards is going against the grain.
If you physically can't get you BS finger to any moving/electrical parts of the machine it's a good thing, right? By extending your probe by a paper clip to get in there.... Well we may as well take the back off most appliances to get the best earth possible!
My advice is, take multiple earth readings from different locations on the fan, if no reading is possible and using your best judgement, i.e age, condition, how & where it's being used etc and make that call, and note why you made that choice. Simple.
Last edited by LeeTurtle on Wed Sep 21, 2011 3:45 pm, edited 1 time in total.
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