Perplexing 12 volt problem-novice please help

B

booboo

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Joined
Feb 21, 2005
RO Number
16369
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168
I added a dual voltage 120 volt and 12/24 volt norcold de0740 to my boat this weekend. Silverton uses this exact model in the same location when it is optioned out on the 45c. I installed it and it works but here is the problem (background first). Silverton so nicely prewired it irrespective of whether or not the option is actually ordered with the boat. On my breaker they have a 12 volt switch pre labeled cockpit refridge and there is an existing red wire connected to it which is for the indicator light that goes on and off when the switch is turned on and off. Here is the problem, once I connect the hot for the 12 volt side of the fridge with the master 12 volt switch on for that "group" of breakers on the panel, the light turns on even if the switch is in the off position. I don't know if the wiring for the 120 has anything to do with it, but the boat is not even plugged into shore power yet. With the fridge powered on via the knob on the fridge and I switch on and off the breaker the light will light up and dim (but not go completely off). With the power on the dial on the fridge switched OFF, sliding the breaker on and off makes far less difference in the intensity of the indicator light on the breaker. I checked all of the other connections, everything is tight. I even switched it to a different breaker switch in the same group and it did the same thing. In fact, if you can imagine the "master 12 volt" switch for the group of breakers in the on position but all other switches "under" that in the off position, as soon as I touch the red 12 volt positive wire to the pole on the breaker in the off position, then the indicator light lights up

Oh.. this MIGHT be important. There is an existing outlet for the icemaker next to this fridge position. I was afraid just plugging it into the icemaker circuit might cause breaker for the icememaker to trip if both kick on at the same time. I went to the hardware store to see if an outlet existed to wire two 120 volt separate circuits into 1 outlet and the guy at the hardware store said I could do the same effective think by breaking the metal bridge between the two outlets on the same 2 outlet affair. I took my needle nose and twisted it until it snapped off. I then wired 120 hot, negative and ground to one outlet side and the other hot, negative to the other side and shared the ground with the other ground. 1) This seems real dangerous in retrospect, 2) could it be effecting what is going on on the 12 volt side??
Help!
 
Did you also hook up the yellow or black DC ground wire on the frig? It maybe backfeeding through the AC ground if you didn't.
Bill
 
Another big issue only make the AC neutral (white) and AC positive (black) break at the outlet. The green wire or ground must be the same on both outlets it is common but needs to be seperate from the neutral white wire.
Bill
 
1st you shouldn't be using any AC wire from a hardware store I assume it is solid wire all marine wire is stranded and is tinned. It sounds like you are creating a ground loop between the AC and the DC circuits you just installed. Make sure you start by disconnecting the new outlet completly (at the panel or where you jumpered the neutral (white) and ground (green). The make sure the frig has a yellow or black (from the DC circuits of the boat) in addition to the red or + wire. Many mistakes are made where unknowing people grab a black wire thinking it is DC ground on a boat when in fact it is AC hot! This creates a very dangerous condition and one of the reasons the color code for DC - was changed to yellow from black depending on the year of the boat. Until you straighten this out I would advise against hooking uo the AC shorepower.
Bill
 
I was hoping someone else would jump in here and try and tell booboo how dangerous, important to correct and costly this mistake can be.
Bill
 
Bill, I did not use hardware store wire, the boat was prewired with tinned copper strand wiring. I only went to ace to find a outlet solution to wiring two diferent circuits into a singe outlet, I thought there was such a beast. The yellow ground was prewired to the ground bus on the dc side and a red hot was available to put on the breaker switch
 
I need more information so what did you hook up? 1st start with the frig not plugged into the AC outpet what happens then apply 12VDC what happens?
Bill
 
same, thing. Guess what, I moved the red 12 volt hot to the opposite side of the breaker and It worked perfectly . I guess it was holding residual current?
 
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