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Old 08-29-2011, 10:55 AM
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txgrassguy txgrassguy is offline
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Join Date: Jan 2007
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Check the ohm readings with a decent multi-meter. Compare the reading from the suspected station against that of a confirmed operating station.
Typically the common wire becoming "hot", as you explain, is almost always caused by one of the multiple common wires leading into a defective station being wired onto the power leg by mistake. This is especially true when the moron who either installed or "repaired" the system before you ran out of white wire and substituted a different color, almost always red.

I have also seen where a previous contractor directly wired the common off of the neutral buss located in a A/C service panel then tied into the field common wiring. This caused all of the solenoids associated with that leg of the common to fry as well as an incredible power feedback directly into the controller. In this instance an ICC which incredibly survived for a year before burning up. When I metered the ICC I was receiving all sorts of wanky readings which I traced back to the A/C unit power source. The ICC was receiving 115 volts so when I opened the service panel I noticed the stranded wire touching the main buss leg above the breaker. The wire insulation had burned through and was completing the circuit causing this problem.
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