To Earth or not earth Steel defibrillator Cabinets.

Hi.

I have just installed an external (public use) Steel defibrillator box with a 40w heater 240v mains feed via a RCD spur.   There is no exposed cables and although the heater looks to be double insulated there is three core mains.  

should I earth bond or not earth the box.  

Is it an extraneous conductive part....

Or an exposed conductive part?

Either of the above may sway your choice......

opcorn

My thoughts exactly,  but when you look at installation information and on-line videos there is no mention of supplementary earth bonding.

think I would bond it, I've fitted a few steel street 'pillars' for external lighting and we bonded the cabinets on these which seems to be standard practice, although I could see little benefit from doing this as the contents were class II.

If the heater is labelled as Class II and the cable is entering the enclosure through a protected entry and no exposed insulation is accessible within the cabinet then the cabinet ought to be a random piece of metal and not part of the electrical installation, in this case the likelihood of the cabinet being an extraneous conductive part is very (very) low and bonding should not be required, and would be prohibitively inconvenient to do (though the latter does not remove the requirement, if it exists).

If the heater is class I and mounted to the cabinet and / or there is exposed insulation and so the cabinet is being used as an enclosure for electrical parts that may cause the cabinet to become live, then the cabinet would be part of the electrical installation and so would require earthing.

From what you describe I would expect that the cabinet would not require either earthing or bonding, but this would be down to your assessment on site as you know the details of the installation.

Thanks for your comments.  the small print says it should be to BS7671 and reg 411.  I have written to the cabinet supplier and said they need to be more specific especially as there are a lot of diy people installing them and wouldn't know what BS7671 was let alone reg 411.  I am surprised this problem has not been flagged up before especially as they are being installed in public places. 

I am going to bond it to some local conduit having checked it's earthed properly.

This has reared its head before but not on here, it was the IET forum. The consensus was the cabinet should be earthed.

Thanks Tony