"Drain" wire in NMEA 200 cabling

http://www.maretron.com/products/pdf/Cabling_Catalog/Maretron%20Cabling%20Catalog.pdf

The NMEA 2000� cable system includes five wires within a single waterproof cable: two signal wires, power and ground wires, and a drain wire. The drain wire shields the signal, power, and ground wires from external Radio Frequency Interference (RFI) and helps reduce RFI emission from the cable.

And from the same doc, the bit that helped me:

"Grounding at more than one location may
produce ground loops, which can cause problems with
communications on the network. In addition to the ground
wire, connect the drain or SHIELD wire at the supply ground
location and NO other place."

What's written above is exactly right, and very well summarized (as long as you don't have a short wave radio with grounding place, which adds another wrinkle)

Note, drain wires and avoidance of ground loops are not unique to NMEA-2000.

You need to provide the same care to a few other devices on your boat, for example some MFD's like the Raymarine e125 have a drain wire in their master cable.

Some manuals make no mention of it, other times different wire was substituted, and the drain shield just appears on the cable unexpected. You then need to determine if the drain of the wire is being used by the installer as drain, power ground, or signal ground.

type, "ground plate", not place.

I have never ask a question on a forum before. I hope this is the right place. I have a furuno MDFBB, 101 Hub. I am to trying to hook up a Vesper BX-6000. I bought a NMEA back bone which I thought I would plug into the 2K on back of the MDFBB. But Furuno says that I have to buy a NMEA 0813 data cable and hard wire to the AIS. I am confused. Can you help?

mstuart, it would be better to start a new Forum topic, but I think I can help you. Your Furuno MFDBB has NMEA 2000 but is apparently not programmed to understand NMEA 2000 AIS messages. It does understand NMEA 0183 AIS messages, so, yes you need to connect the Vesper XB6000's 0183 output to the MFDBB's 0183 input. This will not be plug'n'play but fairly easy for an installer and should work fine. Your install and other manuals are here:

http://www.furunousa.com/products/productdetail.aspx?product=MFDBB