Grounding—optionaldedicateddrainwire
FrequenciesemittedfromequipmentsuchasswitchmodepowersuppliesorMF/HFtransmittersetc.
cancauseinterferencewithyourMFD
’stouchscreen.Ifyouexperienceissueswithtouchscreen
performance,fittinganadditionaldedicateddrainwirecanresolvetheissue.
Note:
Theadditionalwiresupplementsthedrainwire(shield)thatispartoftheproduct’
spowercable
andshouldONL Ybeusedwhentouchscreeninterferenceisobserved.
Connectoneendoftheadditionaldrainwire(notsupplied)toyourproduct.
Connecttheotherendoftheadditionaldrainwiretothesamepointasthepowercabledrain
wire(shield).Thiswillbeeitherthevessel' sRFgroundpoint,oronvesselswithoutanRFground
system,thenegativebatteryterminal.
Thedcpowersystemshouldbeeither:
•Negativegrounded,withthenegativebatteryterminalconnectedtothevessel'sground;or
•Floating,withneitherbatteryterminalconnectedtothevessel'sground.
Ifseveralitemsrequiregrounding,theymayfirstbeconnectedtoasinglelocalpoint(e.g.withina
switchpanel),withthispointconnectedviaasingle,appropriately-ratedconductor,tothevessel’s
commonRFgroundpoint.
Implementation
Thepreferredminimumrequirementforthepathtogroundisviaaflattinnedcopperbraid,with
a30Arating(1/4inch)orgreater.Ifthisisnotpossible,anequivalentstrandedwireconductor
maybeused,ratedasfollows:
•forrunsof<1m(3ft),use6mm
2
(#10AWG)orgreater.
•forrunsof>1m(3ft),use8mm
2
(#8AWG)orgreater.
Inanygroundingsystem,alwayskeepthelengthofconnectingbraidorwiresasshortaspossible.
References
•ISO10133/13297
•BMEAcodeofpractice
•NMEA0400
44
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