Unknown wire

Our DC breaker panel buss bar has two 6 ga cables coming off the buss that are not on breakers.

One I know where goes, it goes to a breakout in the overhead box that the VHF's and the fwd top lights connect to. That lead has a fuse in it inside the breaker panel.

The other has a 90 degree end and runs to the very bottom of the panel cable bundle and I can't see where it goes even within the breaker panel enclosure.

With all the breakers off, those two leads have power. With the DC Main also off, they are unpowered.

Do any other owners have anything similar that could lend some light to the second/unknow lead? I haven't been able to locating anything I know of that runs on DC that is "ON" when all the individual breakers are off but the DC Main is on. When the DC Main is off I get an open circuit on my DVM from the buss bar, at the cable attachment point, to DC ground (when the equipment in the overhead is switched off).

Here is a photo. If anyone knows or has a guess where that cable may go I would appreciate any leads.

Thanks

We have a single head with a recently (a couple years ago) installed Rarritan Elegance computer controlled fresh water unit. It is powered by a separate breaker on the panel (I confirmed it does control the unit), but I need to check as I think it is not switched by the DC main so could have a parsitic draw with the DC main off and the head on (it has a touch pad control).

I'll also take a look and see if an abandoned wire might be present where the old GalleyMaid pumps used to reside.

Thanks.

I checked and the head does not go through the DC main, so when off shore power/charger I need to turn off the Toilet breaker too. It uses a touch pad controll so I expect it has some current drain but I didn't disconnect the toilet controller to measure since I can't get my probe in to that breaker to easily measure.

If I pull the fuse on the line going to the overhead box, there is no current draw, so the mystery wire is not connected to anything.

One current drain is the VHF's, which draw .7 mA when switched off. Unplugged there is still a 0.01 mA drain, which I expect is the ancient DC filter (I don't know that I need that with modern radios so may remove it).

An unexpected draw is the shower sump system. When not running but with it's breaker ON it draws .2 A. It's run by a normal float switch so I don't know why it should pull current not actually running. Further diagnostics on the shower sump are for another day.

Thanks to all

Buss bar is powered by the DC main breaker at it's end (not visible in the photo). The 6 Ga wire running direct from the top of the buss bar goes to a junction block in the overhead. I'm sure the Ga selection is from the original 1980's radar current requirement (it is fused just off of the buss bar connection). It is overkill for the 2 VHF's currently running off of it (each with it's own local fuse at the junction block). The current XHD24 radar connects to a different junction block on the flybridge, which has it's own breaker off the buss bar. The original purpose for the wire coming off the bottom of the buss bar is still unknown, however it shows no sign of being connected to anything.

I re-tested the shower sump several times going directly between power and the connector at the output of the breaker and get 160 mA, still much higher than expected. I opened the sump to confirm it is not a computer pump. It is a standard 800 Rule with float switch. All the connections are near the top of the bilge outside of the sump box so not in or near water (the sump should only see fresh water inside). I guess if the float is a mercury switch if could possibly carry a low current inside from some corrosion or contamination?? I may look at replacing the switch.

I found a different way to get the meter across power to the head controller (Raritan Smart Toilet Control) and get an idle current of 4.1 mA. Seems reasonable for a computer waiting to sense the membrane switch panel.