Q: I spoke to a dealer recently about the use of roller ball-type window and door contacts. His advice was to stay away from them. What do you suggest?

A: The roller ball-type contact can be used at times on windows and doors, but should be used with caution. As with all security devices, it has certain applications that it is better suited for than others.

I would not make it my first contact of choice. Since it is more of a mechanical type device, I agree with many dealers who will tell you they can stick (often in a close position) from dirt, being painted over, or foreign objects.  Because of this, avoid applications that are on the lower half of doors and windows, and those that are exposed to weather. However, it can be a choice if you have an upper area on a door or window that is protected from the elements.  Again, I would only consider it other types of two part contacts cannot be installed easily or neatly.

I would be extra careful in using the roller ball-type contact in commercial applications, as it can be defeated rather easily by sticking it closed with a foreign object. If a customer does use this type of sensor, I would make them aware of the shortcomings and make sure it is inspected and tested often.

Q: We just had a heated debate in the shop over whether to use solid or stranded wire on alarm installations. What do you suggest?

A: You picked a good one here. This is one of those topics that can have good argument on both sides. Overall, I suggest that jacketed and stranded cable be used for alarm installs. It is too easy to nick a solid wire when stripping, and cause it to either break or become so close to breaking that you end up with a potential intermittent swinger situation. The jacketing will help protect from stapling and pulling nicks. On the other hand, a tech has to be very careful terminating stranded as the little wire strands can accidentally short to nearby terminal on the alarm control panel.

You will however start running into more small gauge solid cable in the form of Cat 5 UTP. This cable should only be terminated using the correct push-on terminator and termination posts. In this case, the wires do not need to be stripped.

Avoid trying to strip these solid wire cables with a blade-type stripper as it can very easily nick the solid wire. If you need to strip this type of wire use the stripper that pull the insulation off rather than cutting it.

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