[Alberg30] anchor light wiring

[George Dinwiddie]

OK, Bob.  Disagree.  But notice that 10 watts is not really 1 amp at 12 
volts, it's 0.8333... amps, I just didn't bother to pull out the 
calculator before.  So it's within the 3% guidelines you quote.  You're 
probably dropping more voltage with your wire-nuts than your wire.  And 
the ABYC says a definite "no" to wire-nuts.  But if you feel better 
putting more weight up your mast, go right ahead.

  - George

Robert Kirk wrote:
> At 11:07 AM 2/11/03 -0500, George Dinwiddie wrote:
> 
>> An Aqua Signal series 25 light uses 10 watts.  At 12 volts, that's a 
>> little less than 1 amp.  (watts = volts * amps)
>>
>> 16 awg wire is about 4 ohms per 1000 feet.  The run from the 
>> electrical panel to the top of the mast and back is probably less than 
>> 100 feet as a guess.  So, the round-trip resistance would be about 0.4 
>> ohms.  At one amp, that's a 0.4 volt voltage drop (volts = ohms * 
>> amps), or a 3-1/3% voltage drop.
>>
>> In reality, since the battery voltage is greater than 12 volts and the 
>> current draw is less than one amp, you'll be under the 3% voltage drop 
>> that's considered adequate for electronics, and considerably under the 
>> 10% voltage drop that's considered adequate for lamps.
> 
> 
> 
> George... I disagree. I'm pretty cavalier in using wire nuts, etc, but 
> on the other hand,  I believe you should always use heavy wire for all 
> your circuits. For simplicity & safety sake I wire everything at 12ga in 
> the boat (unless it needs more). It's much easier to buy one coil of fat 
> wire and use it for everything. Then you don't have to calculate every 
> circuit and have a big inventory of different sized wires. It saves time 
> & worry.
> 
> 16 is just too small to use,. It's not much more expensive to use 12ga 
> and it solves a lot of problems.
> 
> The ABYC says:
> 
>    Conductors used for electronic equipment, navigation lights or other 
> circuits where voltage drop should be kept to a minimum shall be sized 
> for a voltage drop not to exceed 3% (See Table C). Conductors used for 
> lighting (other than navigation lights) and other circuits where voltage 
> drop in not critical may be sized for a voltage drop no to exceed 10%.
> 
> It's always nice to measure 12V at the end of every circuit instead of 
> something quite a bit less.
> 
>  Here, I calculate your 16ga wiring gives a 3.3% voltage drop, or 
> roughly half a volt, which is more than recommended for navigation 
> lights. [16ga; 100ft 2 way run; 12V; 1amp]
> 
> Wire is cheap and heavy 12ga wire takes up no more space and gives piece 
> of mind. Don't forget you're going to lose some voltage in the 
> connections in addition to the wire itself.
> 
> Bob Kirk
> Isobar #181
-- 
  ----------------------------------------------------------------------
   Hope your road is a long one.                        George Dinwiddie
   May there be many summer mornings when,       gdinwiddie at alberg30.org
   with what pleasure, what joy,                 http://www.Alberg30.org
   you enter harbors you're seeing for the first time;
                                            from 'Ithaka' by C.P. Cavafy
  ----------------------------------------------------------------------

_______________________________________________

UPDATED: http://alberg30.org/store/AbeBooks.html
_______________________________________________

Public-list mailing list -- Public-list at alberg30.org
http://www.alberg30.org/mailman/listinfo/public-list
To unsubscribe: email to Public-list-request at alberg30.org
Include command "unsubscribe <password>" in subject or body.
Use command "help" for more options.

 1045012832.0