Posted By Simon Walsh Grad IOSH To take each part of your post in turn. I think getting an electrician round twice a year to check each unit is over kill. I would have a look at British Standard 5266 as I feel a check once a year by an electrician is more reasonable. But you should check the lights inhouse every month and keep a record of the tests, and any defects and action taken to rectify. As for causing problems for your servers, here are a few options here to minimise disruption. The emergency lights could be wired into a seperate lighting circuit from the mains, so that when power is cut to that circuit the emergency lights will illuminate, if they do not you have a fault with the system or an individual light. Or you could source a type which have a test button built into the unit. Press the button and the mains feed will be cut to that light and the battery will power the light. The lights are powered by an integral battery which is trickle charged from the mains during normal supply conditions. If the power fails the battery kicks in powering the light for a specified period. Eg a NM/3 emergency light is non maintained for 3 hours duration (non maintained means its off during normal conditions and only comes on when the power fails and stays lit for 3 hours). When it comes to having them installed be wary of over zealous electricians slapping emergency lights all over the place, ask them to produce a scheme which shows where they propose to fit the units and what level of illumination at ground level will be given to comply with British Standard 5266. Just one further thing you will have to turn the mains off to allow the battery to fully discharge to check that the battery recharges properly once a year, so a way to shut down your servers for this will have to be found. Hope this helps

Posted By Simon Walsh Grad IOSH Wobbly or not please keep personal remarks out of this discussion. Turning to your main points, I did not suggest that emergency lighting be installed on the 'same' circuit I did say on a 'seperate' circuit. Most bog standard electricians will not know what installation is required. However a more specialised installer of emergency lighting will know the regs back to front and be able to produce a scheme showing the location of emergency lighting. Emergency lights do not just light up emergency exits, they are supposed to illuminate the means of escape. Means of escape are routes to the emergency exits, and as such the illumination at floor level from units installed on the ceiling (I never said you install illumination on the floor) is critical. This will ensure that steps, ramps and just general changes in floor levels are lit sufficiently to enable efficient egress from the building. The lux level of illumination at floor level is given in the British Standard.

Posted By Eamon I'd like to thank you both for your helpful comments. From what I gather the emergency lighting is on a separate circuit from every thing else and there is a test button which I could use and this would not interfere with any other circuits.