All what was said here makes sense and pin points the issue, So I will aske the question in a different way, if there is so much truble with installing these timers, would it not be more simple (if it is not against the regs.) to put up the timer near the CU, outside and pull the cables to the timer using short trunking or PVC conduit, (so the cable will not be accessible), this way the user can access the timer at any time?

[quote author=ban-all-sheds  link=1112117233/15#18 date=1112396803]That's the other thing - CUs are not designed for convenience when it comes to frequent opening to fiddle with a timer.

A DIN rail mount timer is just a timer - you can put it anywhere in the house, and the rules for running cables to it are just the same as they are for light switches, sockets, FCUs, luminaires etc etc - DI cables on the surface or buried according to the regs on concealment, or singles in conduit.

Personally I wouldn't want a timer in, or even near my CU - even without the space problem it is, like many people's, relatively inaccessible under the stairs. [/quote]

Thanks, this makes it even better.
Albert

[quote author=Jim Franklin  link=1112117233/15#20 date=1112469616]Ban, nothing wrong with timers in CCU's so long as the CCU is sufficiently accessible and that the timer is left in peace to do it's job..and lets be honest here, most are installed then forgotten about for the next 10 years.

In domestic premises and small commercial they are ok inside a CCU, although I personally prefer to put these type of control devices, and any associated contactors, in a seperate DIN rail euipped enclosure. [/quote]

In this case the timer will be used frequently,(every week end and in some holidays), and the clock change will have to be considered iether by the user or it could be built in. from your experience could you recommend a specific timer? digital or mechanical that will be suitable (I know that this is not a place for advertising products, but by having a reference I can look for other makes that will do the same)
Thanks, Albert