Avoiding Alarm Panel Grounding Problems
What are some of the best ways to avoid grounding problems during installations and when designing the layouts of alarm systems? As a new installer who’s had a few problems with grounding I can’t find any definitive advice on the subject in my installation handbooks.
A: In order to keep random voltages off panel zone loops you need to keep your grounding wire short and straight as possible – make sure there are no twists or kinks in the grounding wire.
Never run zone loops and AC power through the same panel knockouts and try to keep them separate inside the panel case as much as possible. Use shielded AC cable, taking the drain wire to the panel’s ground terminal and leaving it unconnected at the plug pack. If zone loops and AC cables must cross paths, make sure they do so at right angles.
When you have no choice but to run AC and zone loop cable in the same tray, conduit or through the same header or stud breach, use more zone loop cable than you need to cover the distance. Let the wire coil up a bit and it will be more resistant to induced AC. Get your digital multimeter out and check panel ground. If it differs to other grounds in the building by more than 2 ohms then you’ve not found true ground and you’ll need to try again.
Finally, read the manufacturer’s instructions carefully and talk to the experts before trying any funny business in relation to system design. Every panel will have a different grounding terminal and you should be very sure of what you’re doing before you start connecting ground wires to unrelated terminals.
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