"Capitol" wrote in message ...
Further comments on this. Chamberlain appear to have lost all their business
in the US. They were the number 1 supplier. The last time I looked, Sears,
Home Depot, Menards & Lowes had all moved over to Genie screw driven
systems. I was unable to buy Chamberlain chain drive spares off the
shelf.(Although they are still available.) Be aware that this may happen
here. My own opener went obsolete 2 years after buying it.

Most photo cell systems operate as normally closed or normally open constant
current switches. It is sometimes possible to add a sensor to an existing
door controller if the electronics can be fiddled appropriately, but it is
not easy. I had to do this, using a Chamberlain photocell system, powered
off a walwart and with the output logic reversed. I don't recommend it. In
the US, there have been a number of children crushed under garage doors when
closing and current practice is always to fit the photo cell units which are
supplied as part of the fixing kit.
Regards
Capitol

Chamberlain makes Sears openers under the Craftsman name &
they also make them under the Liftmaster name. Hence they
are the worlds largest garage door opener manufacturer.
Although they don't look the same they all use the same parts
inside.
Genie is now owned by the Overhead Door Corporation and
therefore those two operators are the same.
Both companies make chain drive, screw drive, and belt
drive operators however you may not see all three types in
some markets. Stores & garage door dealers tend to focus on
marketing only two or three models and while they can get any
of the models they usually do not stock them or they will
simply stock what they can get the best deal on at any
particular time.
Most openers that were made before UL-325 required photo-cells
on all openers in the United States are becoming obsolete since
manufacturers will no longer support these operators due to the
liability issues.
The photo-cells that come w/ the opener are to protect children
or other people from getting injured from a garage door and are
not there to protect vehicles. Per UL requirements the photo-cells
on both sides need to be 3"-5" off of the floor which will be
underneath the ends of vehicles. Therefore anyone that alters the
installation of these photo-cells are very open to some very serious
personal liability issues should heaven forbid that anything tragic
should happen. Once your insurance company learns of this they will
leaving you hanging out to dry in a heartbeat.