Class II with Chassis earth bond?

I understand the desire to avoid the slight tingles, on back-of-finger or a slight cut, that <0.25 mA can give.  Keeping these parts away from the users and lightly insulated from exposed metal seems a good way to achieve that, if it means very little extra cost.


I doubt that it's a good idea in a product to include a connection to the 'PE' of the plug or other connection just for this purpose. If you have a product that's supposed to be produced and sold in bulk for profit, then can you really afford to add to the cost without solid advantage?  I guess that very few users would experience the shocks, and they probably wouldn't be put off the product; and having earthed metalwork is not necessarily a safety benefit (more chance of getting a good earth connection if getting shocked from some other part; and more chance of danger if the PE itself gets a dangerous potential); and extra wires and connections cost money and might need more product-testing; and for other markets (continental) where small 2-pin plugs could be used it means further expense in plugs and possible difficulty for places where earthed sockets aren't available (light-fitting supplies in some countries).  Basically, you would seem to be increasing the cost and doing little or nothing to improve customer attraction. People often don't buy on a technical basis.


1)  I suppose the leakage current would be higher and consistent, when going to a solidly earthed frame instead of through occasional body contact including possible shoes, wooden floor, etc.  But it would be around the 250 uA or less, anyway [Edit: that is, provided that the class-II design already limited leakage to around this much - or 500 uA as GK suggested (later post) might be permitted.]


2) Good question!  I've no idea.  Well - having an earth wire would mean it looks like Class I, but if it doesn't need it for safety it should be Class II.  Perhaps you'd only be allowed the earth if claiming it's needed for safety. In some regulations, the green-yellow colour should only be used when for safety purposes; do you need to call it a functional earth...? Most philosophical: I'll await others' views. 


3) Definitely not something I can answer. Nor most people in a "wiring regulations" forum rather than product standards, LV-directive etc.  But there's at least one regular here who almost certainly will know all of this!  


Concluding:  having a bit of insulation from the supposedly safe leakage-limited parts to touchable metal seems the economic and simple method to avoid occasional tiny shocks.  Failing this, probably just let it be unless your product is analagous to Bentley/RR/etc in its field.

I understand the desire to avoid the slight tingles, on back-of-finger or a slight cut, that <0.25 mA can give.  Keeping these parts away from the users and lightly insulated from exposed metal seems a good way to achieve that, if it means very little extra cost.


I doubt that it's a good idea in a product to include a connection to the 'PE' of the plug or other connection just for this purpose. If you have a product that's supposed to be produced and sold in bulk for profit, then can you really afford to add to the cost without solid advantage?  I guess that very few users would experience the shocks, and they probably wouldn't be put off the product; and having earthed metalwork is not necessarily a safety benefit (more chance of getting a good earth connection if getting shocked from some other part; and more chance of danger if the PE itself gets a dangerous potential); and extra wires and connections cost money and might need more product-testing; and for other markets (continental) where small 2-pin plugs could be used it means further expense in plugs and possible difficulty for places where earthed sockets aren't available (light-fitting supplies in some countries).  Basically, you would seem to be increasing the cost and doing little or nothing to improve customer attraction. People often don't buy on a technical basis.


1)  I suppose the leakage current would be higher and consistent, when going to a solidly earthed frame instead of through occasional body contact including possible shoes, wooden floor, etc.  But it would be around the 250 uA or less, anyway [Edit: that is, provided that the class-II design already limited leakage to around this much - or 500 uA as GK suggested (later post) might be permitted.]


2) Good question!  I've no idea.  Well - having an earth wire would mean it looks like Class I, but if it doesn't need it for safety it should be Class II.  Perhaps you'd only be allowed the earth if claiming it's needed for safety. In some regulations, the green-yellow colour should only be used when for safety purposes; do you need to call it a functional earth...? Most philosophical: I'll await others' views. 


3) Definitely not something I can answer. Nor most people in a "wiring regulations" forum rather than product standards, LV-directive etc.  But there's at least one regular here who almost certainly will know all of this!  


Concluding:  having a bit of insulation from the supposedly safe leakage-limited parts to touchable metal seems the economic and simple method to avoid occasional tiny shocks.  Failing this, probably just let it be unless your product is analagous to Bentley/RR/etc in its field.