Q & A of the Day - Bonding of external roller shutters

Question: I would like to know your views on the bonding of roller shutters that cover entrances and windows of schools, supermarkets and other buildings where the public can be in contact with them. The motor of each shutter is, obviously, earthed via the motor cable to the spur unit supplying the shutter. I am not sure whether the metal rollers or framework is classed as 'extraneous', or whether bonding is necessary. I must say that I have rarely seen any bonded shutters.

Answer: Better to be safe than sorry. This is not our specific area of expertise - contact NICEIC or ECA for a view.

From our point of view, however, if there is electrical contact between the motor and the shutter (i.e., they are not isolated from each other), or possible contact from lighting or other circuits, any fault would result in the whole shutter becoming live. Hence, we would recommend connecting the shutter to the main earth bond with appropriate sized cable. This should be fairly straightforward.

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