Marine Wiring

[dtrman1318]

Can I get 5 new feet of 8 guage wire and connect it to a 6 guage wire which is connected to the battery. It would be about 13feet of 6 guage wire and then 5feet of 8guage wire connecting to the trolling motor. Please Help. Thanx

Dan

 

[Knot Waiting]

Re: Marine Wiring

You should use the same gauge wire when doing a splice. Although any wire can technically carry a current changing the gauge along an electrical path can have seirous, even dangerous, consequences. Too large a gauge can cause a significant increase in ohms and reduce the total voltage being carried. Too small and the wire may overload and short out resulting in a fire.

 

[bruceb58]

Re: Marine Wiring

You should use the same gauge wire when doing a splice. Although any wire can technically carry a current changing the gauge along an electrical path can have seirous, even dangerous, consequences. Too large a gauge can cause a significant increase in ohms and reduce the total voltage being carried. Too small and the wire may overload and short out resulting in a fire.

Depends on the voltage drop that is tolerable. He just needs to calculate the drop for each piece of wire given max current. If at all possible stick to one size although I can imagine certain scenarios where that is not possible.


When a wire overloads because of heat, it does not short out. It may open...it mat get hot enough to catch something on fire...it won't short out.

Curious...why not just add a length of 6 gauge.

 

[Boatist]

Re: Marine Wiring

Yes you can use 8 guage if it will carry the current you need. The smaller 8 guage will have more resistance and drop more voltage. However if you do splice the lighter 8 guage to the 6 guage wire then you should change the fuse or circuit breaker to the correct amps for 8 guage. This prevents the lighter 8 guage from overheating and catching fire. Instead the fuse will blow or the circuit breaker trip.

Under stand if your trolling motor need the max current that 6 guage can supply then using 8 guage will reduce the power of your trolling motor and may blow the smaller fuse.

If I am going to change size like that which is very rare I like to go to a terminal block and then connect the smaller wire with the fuse for it at the block.

 

[Silvertip]

Re: Marine Wiring

It would certainly help to know how big (thrust) the trolling motor is. 55# has roughly a 50A draw max. Take that and the total run of wire up and back and run the drop calculation.

 

[turbinedoctor]

Re: Marine Wiring

You should use the same gauge wire when doing a splice. Although any wire can technically carry a current changing the gauge along an electrical path can have seirous, even dangerous, consequences. Too large a gauge can cause a significant increase in ohms and reduce the total voltage being carried. Too small and the wire may overload and short out resulting in a fire.

Bruce already cleared up the issue with Shorting out verses opening up, there is another point that needs to be corrected.

Too large a gauge can cause a significant increase in ohms and reduce the total voltage being carried.
The larger the wire or cable the lower the resistance and the more current it can carry with less voltage drop.

Use good splicing practices and size the fuse for the smallest device in the circuit and you should be OK.

Durwood

 

[JustJason]

Re: Marine Wiring

length and load will tell you what minimum gauge you need.... but it never hurts to go bigger.

 

[RickJ6956]

Re: Marine Wiring

Too large a gauge can cause a significant increase in ohms and reduce the total voltage being carried.
The larger the wire or cable the lower the resistance and the more current it can carry with less voltage drop.

Clarification: A larger gauge means a smaller wire. (The higher the gauge number, the thinner the wire.)