What's the problem with horizontal cable runs for the power/LAN cable?

[Arcturus]

The installation manual for my DRS4D-NXT radar states "Make sure the power/LAN cable and cable assembly does not run horizontally...". I haven't been able to find an explanation for this statement, and find it hard to believe that most installs have the MFD located directly below the radar transducer. I was planning on running my cable horizontally along the overhead for about 14' from the mast to the MFD installation. Will this cause problems?

 

[Bayhouse]

My DRS25ANXT power/LAN cable runs horizontally across the top of my hard top, down a tube, horizontal over to the location of the MFD and up to the connector - no issue at all with the install. Damn great radar.

 

[Johnny Electron]

Running horizontally isn't a problem in itself unless running alongside other wiring that can lead to inductance or EMI issues. In other cases they sometimes talk about direction to prevent water from running along the cable etc. I would have to look at the full context of what you are talking about. Do you have a page reference?

 

[Arcturus]

Sure! Furuno Installation Manual, Radar Sensor, Model DRS4D-NXT. Section 1, Pg 3, Cable Routing.

 

[Johnny Electron]

Thanks!

Yes, the entire concern is related to picking up RF transmissions or EMI inductions both from on the boat and surrounding boats/area. Long horizontal runs could act an antenna. When the units are properly grounded with the provided shielded cable, it would have to be pretty strong but their point is taken.

 

[Arcturus]

Thanks, that makes sense (though some idea of how long a horizontal run needs to be before picking up signals is likely to become problematic would help).

I could see that as a statement like "Where possible avoid long horizontal runs, especially over xx feet." or similar. The "Make sure.,.cable and cable assembly do not run horizontally" is a very strong message, especially when given without elaboration.

 

[Johnny Electron]

Like antenna length, it would have to do with a size of the signal wavelength you are trying to or not to pick up. Cell RF is small wavelength and HF would be long. I wouldn't get to wrapped up about it. Proper power and grounding is the most important thing.