whats the go with 6mm wire.
Submitted: Saturday, Jan 31, 2004 at 21:53
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Diamond(due to duck season)
after reading heaps about needing 6 mm wire to run fridges ect .
after getting a 90 ltr weaco and trying it out last weekend and the lead not being big enough to reach the standard cigarette socket in the can i found a cheap and nasty extention lead(12volt)and had to use it to run the fridge.
now the question.this lead would be lucky if it was 2mm but still run the fridge like a dream why the importance of using 6mm wire.
i will be using 6mm to wire the fridge permanantly but didnt have a problem with 2mm.
only reason ill be using 6 mm is because it is what most people recomend .
but why
thank you for any imfo.
cheers due to duck season coming
ive decided to hide out
love jemima puddle duck
back after the season
Reply By: Mad Dog Morgan (Geelong) - Saturday, Jan 31, 2004 at 22:41
Saturday, Jan 31, 2004 at 22:41
Here's the formula for voltage drop
Length of conductor in metres x current in amps x resistance of copper divided by the conductor cross section in sq mm.
The resistance of copper is 0.017
Remember the length of conductor not only includes the + cable but the earth return cable also.
6mm auto cable does not typically have a conductor of 6sq mm as this includes the insulation as
well. There appears to be no standard, best to have a look at the writing on the roll or asking when purchasing.
So the question remains what is an acceptable voltage drop with these fridges...anyone know ? BEAM ME UP SCOTTY
Hooroo
Ray
AnswerID:
45006
Follow Up By: Brett - Sunday, Feb 01, 2004 at 17:44
Sunday, Feb 01, 2004 at 17:44
does the resistance of a power cable vary with the insulation type?
FollowupID:
307212
Follow Up By: Mad Dog Morgan (Geelong) - Sunday, Feb 01, 2004 at 18:17
Sunday, Feb 01, 2004 at 18:17
I don't know Brad, if it does have any effect it would be so little as to be negligible I expect. If I remember correctly temperature has a small effect but 0.017 ohms/metre is the accepted figure. BEAM ME UP SCOTTY
Hooroo
Ray
FollowupID:
307215
Follow Up By: Brett - Monday, Feb 02, 2004 at 18:17
Monday, Feb 02, 2004 at 18:17
I was being a bit pedantic. In my High Voltage days I think we needed to roughly know the lenght and insulation type and factor this into calculations to determine cable faults.
I agree, 0.017ohms per meter is more than accurate enough for the majority of calculations.
Thanks for the info Ray
Brett
FollowupID:
307282
Reply By: Member - JohnR - Saturday, Jan 31, 2004 at 22:46
Saturday, Jan 31, 2004 at 22:46
Diamond the explaination above gives most of the answer. Electricity is like water in some ways- the more you want volume wise (amps) the bigger the pipe needed or you need more pressure (volts).
You could cause a fire of course if the wires got too hot because they are too small. Yes, a compressor is the other reason you may want to go bigger, especially if you get some hot conditions.
Jemima looks more like a sitting duck than one one would be interested in shooting.Regards
JohnR - Not enough of the right travelling, some here..... some over there.......
AnswerID:
45008
Reply By: David O - Sunday, Feb 01, 2004 at 18:00
Sunday, Feb 01, 2004 at 18:00
I learned the lesson the hard way- though my fridge is a Chescold three way which draws about 10.5 amps.
I had twin fles running the length of the car from the aux battery and could never get the fridge to work, simply woiuld not work. I also fried my alternator. I put in a new 85 amp alt and did a
test. With the engine running and 13.5 volts at the battery, I had 10,4 volts at the fridge with the fridge on full cold.
I ran 6 mm wire, and the fridge works fine plus the voltage drop is less than 0.7 volts.
AnswerID:
45063