Correct Wire Size for a Marine Stereo

[gillmeone]

I'm trying to determine what size wire I need to hookup a marine stereo (just a digital media receiver w/radio) on my 25ft pontoon. There is no circuit boards or switches. This boat does not have any guages or anything currently hooked up. My plan is to run the yellow and red wire from the stereo to a toggle switch and run the ground from the stereo to the toggle switch (lighted rocker switch), and then from the rocker switch run a black and red wire (in a jacket) back to the battery's positive and negative posts. Will need approximately 15-20 feet of wire. I will be putting an inline fuse back by the battery on the red power line. The stereo is a 200 watt stereo 50 x 4 (no separate amp or anything) and I will only be hooking up 2 speakers. I need to know what size of red/black jacketed speaker wire I need. I know I have some 16ga at home, but I've read several articles stating it should be at least 12-14ga if not 8-10ga. I've read that if you have too small of wire, it can cause your speakers to cut in and out or for the head unit to power off and on periodically.

Any help you can provide would be greatly appreciated. Also, can you confirm if how I plan to do the wiring sounds appropriate?

Thanks!

 

[MH Hawker]

14 ga should do fine

 

[jhebert]

I'm trying to determine what size wire I need...to hookup a....stereo is a 200 watt...

If your loudspeaker amplifier produces 200-Watts of output, we can figure its input of electrical power will be greater. Let us assume the efficiency of the amplifier is about 66-percent. This suggests it will need 300-Watts of electrical power.

If the system voltage is 13.2-Volts--a nominal figure for a "12-Volt" system, we can estimate the current as 300/13.2 = 22.7-Amperes.

If the length of the conductor is not more than 12-feet, and you wish to maintain a 3-percent voltage drop limit in the power distribution for a current of 22.7-Amperes, you will need a conductor of 8-AWG. If the conductor is to be more than 12-feet, you need to increase the conductor size to prevent the voltage drop from exceeding 3-percent.

I doubt you could tolerate the sound of a 200-Watt audio system all the time on a small boat, so figure the average power will be much less. On average the power will be more like 20-Watts. The current will thus be 20/13.2 = 1.5-Ampere. A wire of 16-AWG can handle that current.

You can pick the size of the conductor to be somewhere between 16-AWG and 8-AWG based on your estimate of how much electrical power you will be consuming based on how loud you will be asking the amplifier to drive the loudspeakers.

 

[gillmeone]

Thanks for the responses. Just 1 more quick question to clarify, can I use 12ga "speaker wire" to run back to the battery's positive and neutral posts or does it have to be electrical wire? My plan was to use speaker wire as I have to get a bunch to do some outside wiring of speakers at the lake anyways and I should have more than enough left over from that to run on the boat for the power and ground if it would work. I'm pretty sure it should work fine, but want to make sure it would be safe.

 

[bruceb58]

16 ga speaker wire is plenty big for 50W assuming 8 ohm speakers. Only going to be a couple amps.

Don't use speaker wire as power wire. Besides the fact that it is hard to tell the positive from the negative, it's just a kluge way of doing things and will not help another person ever working on your boat.

 

[NYBo]

Welcome to iboats!:welcome:

Chances are 16 gauge will be fine for the power leads. What size fuse is recommended for the stereo?

Don't use speaker wire as power wire. Besides the fact that it is hard to tell the positive from the negative, it's just a kluge way of doing things and will not help another person ever working on your boat.

Good advice. You don't want to mix up speaker and power leads so it would be best not to use the same kind of wire for both purposes.

 

[jhebert]

...can I use 12ga "speaker wire" to run back to the battery's positive and neutral...?

You can. It is your boat. It is not recommended. On a small boat the length of any conductor can't be very long. It does not make very much sense to save $5 in the cost of the proper wire and use something non-standard. In terms of the cost of a boat and cost of operation, the cost of 20-feet of wire to do the job properly is totally insignificant.

 

[bruceb58]

Most auto stereos with this 200W(50Wx4) rated outputs use 10A fuses. That alone tells you that you can get by with 16 or 14ga wire depending on how long your run is. Using anything like 8ga is a waste of money.