The Fire Precautions Act, The Fire Precautions (Work Place) Regulations and many other pieces of Fire, Safety and Building legislation govern the servicing of Fire Alarm Systems. Some say it outright and others only imply it. Some legislation carries with it heavy penalties. 

Whether you believe you are obliged or not, you have a lot of capital invested in your Fire Alarm System. This would be wasted money if it didn't work. When you need the Fire Alarm System to work it will be to save someone's life, your property or your business so it must work properly. The only way you can be confident that it will work is if a professional company using properly trained and qualified engineers regularly services it. BS5839 requires Fire Alarm Systems to be serviced at least four times per year.