Is all Gauge Wire the same?

[Sugo]

I need to run heavier wire in my 21 ft boat from the batteries at the back to the panel at the front. As I have accumulated more electronics the 12 gauge wire I have now has too much drop in voltage under load. I am planning to run 4 gauge wire. I priced it at the marine shop for $3.75 a foot. I found a 20 foot set of jumper cables that are 4 gauge at Princess auto. Are there disadvantages to just cutting off the ends of the jumper cables and using the wire over purchasing 4 gauge wire.?

 

[MH Hawker]

Re: Is all Gauge Wire the same?

You can do that, how ever it will be plain copper wire and it will corrode even through the jacketing over time and cause issues, long term it is better to get a tinned type of wire that wont. Remember to add a bigger fuse at the battery for what ever wire size you add.

I used a 8 gauge on mine last year when I did a full rewire and used a ATU blade style fuse holder, around here its easier to find and a 50 amp fuse is common.

 

[NYBo]

Re: Is all Gauge Wire the same?

Four gauge is overkill. Ten or 8 is generally sufficient. You can get a lot of years out of non-marine wire IF you are boating in fresh water. If you are boating in salt water, tinned is the way to go for longevity.

 

[smokeonthewater]

Re: Is all Gauge Wire the same?

Four gauge is overkill. Ten or 8 is generally sufficient. You can get a lot of years out of non-marine wire IF you are boating in fresh water. If you are boating in salt water, tinned is the way to go for longevity.

what he said... The wire on your alternator is likely just 10 gauge..... 10 would be plenty for most boats and if 8 will likely carry more than the alternator will supply.

 

[jhebert]

Re: Is all Gauge Wire the same?

The concept of assigning a designator of a wire "gauge" is intended to provide a way for wire size to be measured in a standard manner. The usual wire "gauge" is the American Wire Gauge standard, usually indicated by AWG and a number For example, a wire that met the standard for AWG-8 wire would be marked with AWG-8 on its insulation. Any wire marked AWG-8 should be of the same cross section size. However, it has been reported that some wire made in Asia is unscrupulously marked with an indicator that is too generous, that is, for example, a wire marked as AWG-8 might really only be AWG-10 wire. The size of the insulation is typically increased so that the difference is not remarkable until you strip off the insulation.

The entire basis for having a standard is to provide a consistent way to indicate wire size. One AWG-8 conductor should have the same equivalent cross section area as another AWG-8 conductor. There are many other properties of wire in addition to its cross section. Wire used on boats should be compliant with USCG regulations and also with ABYC recommendations. Those specifications include other factors besides just the cross section area or wire gauge.

 

[Ike-110722]

Re: Is all Gauge Wire the same?

Wire used on boats should be compliant with USCG regulations and also with ABYC recommendations. Those specifications include other factors besides just the cross section area or wire gauge.

What the CPO said. The key here is voltage drop. You need to minimize the voltage drop over the distance from battery to panel. I agree 4 ga is way overkill, and you should not use the auto jumper wire. The number one cause of fires on boats is electricity. Electrical fires are most often caused by high resistance connections and corroded wire. Do it right. Saving a few bucks here can get you into big trouble later.
You need to determine the size wire you need. See here, for how to do that. New Boatbuilders Home Page - Electrical Standards Page 3 - Wire Sizes
There is a table that is easy to use at New Boatbuilders Home Page - Electrical Standards Page 4 - Wiring Voltage Drop

 

[Sugo]

Re: Is all Gauge Wire the same?

The reason I was thinking 4 gauge was the distance. From my batteries I am looking at 15 feet in each direction to complete the loop. I have an old school radar, cd player, VHF, an inverter running a laptop and external screen for my GPS and so on. I have been looking at some charts on voltage drop based on amperage over distance but have not found a chart that match the exact application. I have 2 (new) 12V deep cycle batteries (900cca each) in parallel and a 10 amp charger on my kicker that runs all day while fishing but still I still experience voltage drops that cause my radar and to automatically shutdown. This is with the 12gauge wire I am using now. Is marine wire labeled differently than automotive? The roll I looked at at the marine store looked exactly like the roll at the automotive supply. Thanks for the input guys!!

 

[Sugo]

Re: Is all Gauge Wire the same?

I am such a slow typer Peter posted the answers before I could post the questions. Thanks for the links

 

[Ike-110722]

Re: Is all Gauge Wire the same?

There are various types of marine wire but most have a label on the wire or on the package that say UL1426. There is some auto wire that is also marine compliant. I have seen wire in auto stores that say marine on the label. But you can get UL 1426 tinned wire on the internet just as cheap as buying from an auto store. You are in BC. I am in Washington. You could probably order it from Fisheries Supply in Seattle Fisheries Supply - Marine Supplies Since 1928. That's where I buy it. Of course I don't know how long it would take or if there is a customs duty. I am sure there must be someone in Vancouver that carries marine wire.

 

[Sugo]

Re: Is all Gauge Wire the same?

Based on the distance and the amperage it looks like AWG 8 is what I should use. For safety on a 30 foot loop of AWG 8 what is the maximum fuse size I should have in this line? How do I calculate the amperage draw from the inverter I use to create 110V AC to plug in my lap top (19V DC) and my external screen (12V DC)?

 

[tazrig]

Re: Is all Gauge Wire the same?

Hope this helps:

http://www.wattco.net/infopdf/wireguagechart.pdf

 

[Don S]

Re: Is all Gauge Wire the same?

A 40A breaker can be used with #8 ga. wire. 30A is typical on most small boats. You would have to be really power hungry to use 30A all at one time.
Your inverter should have the amperage draw on it. Or ask the manufacturer if that inverter.

 

[Silvertip]

Re: Is all Gauge Wire the same?

When using an inverter there is a 10:1conversion factor to consider. If a 120 volt AC device draws 1 amp, the inverter will suck 10 amps from the batteries. Look at the current draw labels on your devices.

 

[Ike-110722]

Re: Is all Gauge Wire the same?

Look on the back of your lap top. It should have a label giving the voltage and wattage. Divide the watts by the voltage. That's your current. Do the same for all devices on the same circuit. Add them up. That's your total current draw. If you have more than one circuit do the same for each. On a boat the size of yours I doubt there are any 30 amp circuits. would keep it to 20. That is what they are on my 18 footer. (of course it is much much older than yours)

 

[jhebert]

Re: Is all Gauge Wire the same?

Based on the distance and the amperage it looks like AWG 8 is what I should use.

In a 12-Volt power distribution system the wire gauge will have to be sized for voltage drop instead of for current handling if the wire run is more than a few feet. You will generally find that the wire size for a run of 30-feet will be several sizes larger than needed for the current handling capacity because it will be necessary to account for the voltage drop. In higher voltage power distribution systems the voltage drop is not as influential in wire size selection, and consideration of the current is more often the determinant of wire size.

If you use a calculator for wire size, be sure the calculator accounts for voltage drop, not just current. Also be sure that the distance measurement is consistent. Sometimes the calculator expects you to enter the total loop circuit distance and sometimes a calculator expects only the one-way distance. You have to adjust your input data accordingly.

 

[Don S]

Re: Is all Gauge Wire the same?

Circuit Wizard

Typically, voltage drop of 10% is used most marine electrical and electronics.
Even your electronics will work from 9 to 15 volts.

Marine grade wire typically has 105? C insulation rating.
Example
Tinned Copper Primary Wire Single Conductor 105? C (UL) - iboats

 

[smokeonthewater]

Re: Is all Gauge Wire the same?

I'm gonna venture a WAG that your radar shuts down when you flip the switch to turn on your inverter or a similar situation... If that is the case then a capacitor up front might be a good idea to help maintain a constant smooth power supply.

Fact is though that with a 30 amp draw and a 10 amp charge you WILL see a reduction of voltage throughout the day and you MAY have to consider curbing your electric usage. Another option would be to run your inverter from a separate deep cycle battery that you charge at home and keeping the other electronics hooked to the battery being charged by the motor.

 

[Sugo]

Re: Is all Gauge Wire the same?

It's rare that I am using all the big draw items at the same time. The lap top and screen for my GPS, depth sounder, power down riggers and maybe the radio make up the usual suspects. As I am doing some rewiring I wanted to get some input to do it right and be set up for worst case scenario. Thanks again for the education.

 

[smokeonthewater]

Re: Is all Gauge Wire the same?

ANOTHER thought... why not leave the 12 ga for the radar and vhf... Add an 8 ga for the rest.... then if you DO use too much at once for the length of 8 ga and get a little voltage drop your electronics would unaffected

 

[jimbo_jwc]

Re: Is all Gauge Wire the same?

Not all same size gage wire is rated for the same amperage . Solid wire is always rated lower than multiple fine stranded wire as the current flows around the surface/skin of each strand plus the more strands is more flexible . Jumper cable wires will handle more current because of this . MTW machine tool wire has fine strands and flexible with oil resistant insulation . After years of fixing Loco's ,Locomotive Cranes ,Mules,Shovel Loaders,Mobil Cranes my favorite to use is welding lead with almost unbelivable amperage / voltage ratings and insulation that holds up to the roughest enviorments . Only draw back is price. I would solder then crimp connectors on then silicone with shrink tube to make water tight as mechanics loved using New Hotsy pressure washer so much.