Wifi extenders and the bonding system

Scott SV Tengah

Hi all,

This is really a question about bonding, which I'm very weak on. 

We have been using a Wirie Pro wifi extender on our A54 for over 2 years and while the Wirie didn't work that great, I separately used the Ubiquiti Bullet M2HP titanium which was part of the package and that worked great. It was mounted on a plastic Pelican case and therefore electrically isolated.

Recently, it died and I needed a replacement but the Bullet M2hp-Ti is no longer being made. I went for an Alfa Tube 2HP, which is generally quite similar.

The problem with all these devices is that the antenna port is typically connected internally to device power. So when you mount the device on a rail or on the masthead, it sends voltage to the exterior metal and hence the Amel bonding system. The old Bullet was mounted by Wirie Pro in a plastic Pelican case, but I am almost certain the Bullet's antenna port was connected to power also. The Alfa's design doesn't make it easy to mount on the same Pelican case.
Since our A54 is 24v,  I had to use a DC-DC up-converter to get 48v which is then fed into a Passive PoE Injector for my Alfa. The PoE injector is just a simple device that adds power to some of the wire pairs in the the ethernet cable - that is how the device gets power. Once I plugged in the powered ethernet cable into the masthead mounted Alfa, the tester light on our Amel for BOTH + and -  lit up and using a multimeter I saw voltage in our rigging. That is obviously not good.

A few questions:

1) Is the fact that the Alfa runs on 48v and the rest of the boat is at 24v the reason why the Amel tester lights up? If this is the case, I can buy another wifi extender that will run on 24v. That doesn't seem likely as the 24v device's antenna connector would still be energized, but I figured I'd ask.

2) The other option to run the Alfa is a 220vAC power brick run on inverter which then provides 48vDC to the Alfa. Very ineffiecient but in this case, the Amel tester light does NOT light up, probably because the power brick isolates the 48v being provided from the boat's 24v battery circuit? But I presume the rigging is still being energized with 48v? But without a way for the power to complete the circuit through the rigging and get back to the source of the 48vdc (power brick), is this not a problem with respect to corrosion?

I hope my question is explained well enough because my understanding of bonding is quite thin. Many boaters use these wifi extenders and no one has talked about this issue but then again, most of them don't deal with our floating ground bonding system.
2007 A54 #69
SV Tengah

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