HARMONICS?

[Knox]

I have an issue at a customers residence. About a month ago we installed 6 T8 4 lamp 8' open strip fixtures in his garage. At the time everything worked fine. Two weeks later ADT came and installed a security system. Since that time, whenever the customer turns on the garage lights the central vacuum system in the garage turns on for a brief second and then everything works fine. The only time it happens is when the lights in the garage turn on, could this be an issue with harmonics and if so what would be a common fix for it? I never seen anything like this before. Thank you in advance for your help.

 

[charlie b]

It's not harmonics. I would apply the rule of thumb that when something suddenly goes wrong, take a look at the last thing that was changed. If this problem really did not happen until the alarm system was installed, then odds are that some aspect of its installation is the culprit. So I would look at the way the alarm system was installed, or at least any part of the alarm system that is in the garage. I would look for proximity of conductors related to the lights, conductors related to the alarm system, and conductors related to the central vacuum system's controller. It sounds like you are getting a transformer interference (i.e., magnetic field generated within the lighting circuit wiring causing current to flow in some other, nearby but unrelated wire. It could be just severe enough during the time it takes to energize the lights to have an impact, but not severe enough during normal lighting operations.

 

[Besoeker]

I would apply the rule of thumb that when something suddenly goes wrong, take a look at the last thing that was changed. If this problem really did not happen until the alarm system was installed, then odds are that some aspect of its installation is the culprit.

Good, practical common sense, Mr CB.
Don't invent esoteric theories until you have positively ruled out the mundane.

 

[GoldDigger]

With respect to the transformer interference, I would look closely to see whether the alarm installers created an illegal ground to neutral bond after the mandated bonding point.
This could allow the return side of the lighting circuit inrush current to follow a path which was not intended (e.g. EGC or raceway) causing an unbalanced current where there was a balanced current originally. Hence a larger magnetic field to cause interference.

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