I have a veritas 8c alarm which keeps going off?

If it's going off in the day when unset the problem is certain to be related to the tamper circuit and poss in the bell box. If trhe bell box is oner of the older types then "in the summer" when it gets hot it distorts and releases the tamper switch inside the bell box. I suspect that during the day it is only the inside sounder that goes off not the bell box itself.I think that will be your problem

Geoff
May 2011

Now tell us what is lit up when this happens

Alarm
May 2011