Good evening, i work for a property company that lease space to SME, i currently and have always performed the weekly bell test, recently they have employed facilities managers and they have demanded that bell tests are performed exactly at 10am, now i always assumed there was a small window to perform test e.g. 9.45 - 10.15 which with the demands they have piled onto our aready hectic workloads gave us a chance to complete all PPM.

Is there any legislation on this ?

Regards. 

The BS states they should be carried out at approximately the same time each week, therefore +/- 15 minutes i would consider acceptable, just try to get it as close to 10.00 am as you can.