120 volt AC systems have 3 wires: black, white, and green. These are connected to a system on shore where the 120 volt hot wire is black, the neutral wire is white, and the ground wire is green. At some point ON SHORE the neutral and ground bus wires are tied together. NO PLACE on a BOAT should these systems interconnect! Possible reasons: Someone switched the green and white connections wiring something. Wet connections with salt water bridging the white and green sides. Equipment somewhere is defective allowing an interconnection.
Turning breakers off and on usually won't find these because the breakers do not interrupt the white wire. This is an area that you really need to pay a good electrician for if you don't know exactly what you are doing. I was once badly shocked by an air conditioning pump with swapped green and white wires while standing ON THE DOCK. The pump started and pissed on my leg with 120 volt water! Joe Della Barba Coquina C&C 35 MK I From: CnC-List [mailto:[email protected]] On Behalf Of Tom Buscaglia via CnC-List Sent: Monday, June 02, 2014 2:47 PM To: [email protected]; [email protected] Subject: Stus-List AC wiring I received the following email from our club regarding our AC electric. Any C&C listers able to elucidate as to what this means and what you would anticipate it will take to correct? Tom, I have been doing electrical tests on new boats in QYC docks recently. In reviewing the records of previously tested boats I noticed an anomoly in the recorded results of one of the tests that was done on Alera. Apparently, I overlooked or ignored this when I tested Alera. One of the measurements recorded indicates a very low resistance (20 ohms) from your AC plug neutral wire to the AC plug ground wire. All the other measurements were high resistance and OK. This low resistance would indicate that your boat's AC system has the neutral wire connected to AC ground somewhere. While this is normal in home wiring it is not standard on boats. It creates a shock hazard. It is against ABYC standards for small boat 120 VAC, 30 A systems. I highly recommend that you have this looked into and corrected. I would be happy to help you checking this out if you want to deal with it yourself. J thx Tom Buscaglia SV Alera C&C 37+/40 Vashon Island WA (206) 463-9200 www.sv-alera.com <http://www.sv-alera.com/>
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