Hello, Is there any specific safe distance or measurement that a combustible. e.g pallets of cardboard should be stored away from a potential ignition source e.g large electrical distribution board. (warehouse) I am aware that its good practice to keep combustibles away from sources of ignition, but am interested to know if there is any specific distance quoted in any guidance, I have had a quick look today and cant seem to find anything.

Think you have a problem if an electrical DB board is a serious source of ignition. To some extent the safety distance will depend upon the anticipated heat out put of a typical fire in the area. If I remember correctly, cardboard will auto ignite about 12.5kw/m^2 heat input.

FM Global recommends 1.5 metres between electrical equipment and combustible material. See http://www.fmglobal.de/h...faq---english/index.html

I would probably recommend to enclose the electrical equipment inside a cupboard built around it. As well as a safe space between it and the cardboard. Otherwise store the cardboard elsewhere.

An arc flashover is something you would associate with HV switching not an MV/LV distribution board. Materials of any description or substances must not be stored within switch rooms. MV and LV equipment if maintained appropriately will not present a risk however adequate clearance must be maintained so that access to the equipment is possible at all times.

Not if designed, installed, used and maintained properly - as per EAW Regs and relevant standards.

I've had a brand new DB catch fire in a new multi storey office building. I was caused by a grub screw that wasn't tightened sufficiently during assembly. not a component touched by the electricians who fitted it. the vibration caused by the current worked it loose and the contact starting arcing generating enough heat to cause the insulation to catch fire.

'the vibration caused by the current worked it loose' How does electrical current, in itself, cause vibration? I'm not an electrical engineer - so I stand to be corrected on this. However certainly sufficiently aware of general electrical principles. Never heard of this.

Sounds like you have it covered well enough but you should ensure the door is kept shut and locked, safety signage of course, and still maintain a safe distance from any storage. I would also recommend not storing anything combustible or flammable anywhere near the electrical equipment, despite what anyone else says about it. There should always be plenty of room for access to the electrical equipment at all times. Also have a C02 Extinguisher handy, not too close to the electrics, just so it is accessible if there is a fire. Further if you do store anything in there make sure you have the right extinguisher/s for the risk. Fire risk assessment needs to be reviewed as and when anything changes. Seems to me you have the fire risk assessment well in hand.