Wire gauge for mobile ICOM in a Jeep

[FIREUP]

Gents,
It's been a bit since I've been here. I'm hoping this is the right place to ask this. I'm installing an older ICON 2000 in our '15 Jeep JKUR and, it came with some seriously large wire attached for power and ground. It also has a fuse on both of them. So, I'm doing a bit of ohms law math here and, based on the fact that the radio is a 50 watt radio, using ohms law, that equates to about 4 amps at 12.5 or 13.0 VDC. And that means, if you look up the appropriate wire gauge for that kind of amp load, you get 14 AWG. That is at least one size smaller than what the radio was attached to from a former owner using it. The actual wire leading from the back fo the radio is very close to 14 GA. It's after the plug that was installed in both the power and ground, about 8" from the radio, that the gauge of wire thickens.

I'm wondering, the run for power and ground, isn't gonna be more than about 5'-6 or 7' away and, directly tied to the battery, via a fuse. I'm thinking that the boys that create those amperage/wire gauge/voltage/feet charts, kind-a know what they're doing. But, I thought I'd ask on here for those that have done this sort of thing. I appreciate any answers here.
Scott

 

[jwt873]

I'm running an Icom IC-7000 in my 2016 JK. (It draws up to 22 Amps). I used 10 Gauge run directly to the + and - terminals of the battery. The run is about 8 feet. Works OK.

FWIW, there are aftermarket power cords available for your radio. It appears they use 10 gauge as well.. I'd just buy one of these rather than splicing etc.. -> https://www.amazon.com/WORKMAN-IC2000-RADIO-POWER-Workman/dp/B01AQ82NFU It's 6 feet long, but should be enough.

 

[ramal121]

Transmitters are not 100% efficient. For a 50 watt output you may be pulling upwards of 75 to 100 watts from the power source, Check the mfg specs for actual current draw then recalculate.

 

[SteveC0625]

Wrong use of the formula! RF watts are not DC (or AC) watts.

Find the manufacturer’s specs for the radio and size your wire based on their current draw.

 

[mmckenna]

It's common for a 50 watt VHF or UHF radio to pull anywhere from 9 - 13 amps when transmitting.

14 gauge wire is sufficient for your short run, bigger won't hurt. Don't go too small, either.

The formula for this is:

Amps x loop feet x 11.1
—————————————— = Circular MIL area of wire.
Allowable voltage drop

If you allow for 15 amps of draw for your radio, 15 "loop feet" (length of positive and negative power feed) and use the 11.1 constant for TW type copper wire and divide that by allowable voltage drop (1 volt is generous in this application), it works out to about 2500 CMA, which is roughly 16 gauge wire. Taking a step up is a good idea, as the cost is minimal.

IF you are installing one radio, that's good enough. IF you ever plan on adding more, it's a good idea to install something bigger to support more radios. Labor is the expensive part when you are looking at short cable runs.

 

[FIREUP]

Wow,
You guys, as usual, are GREAT! I really appreciate all your experience and help here. Obviously, I've never been, am not now and will not be any form of electrical guru. The stuff's always been over my head. Basic 12VDC stuff is just fine. Super basic 120VAC stuff is fine. But, beyond those two, I'm lost. So, it looks like some say 14-16 ga will work while others, surely stipulate the use of 10GA for my application. I buzzed through the owners manual for the ICOM 2000 and couldn't find any specs on wiring setup.
One more thing, the power wires that emerge from the radio, clearly are not 10GA. They're much closer to 12GA or 14GA. But, that's for only about 6" or so. Then, there's a square duplex plug. On the other side of that plug, appears to be 12GA or even maybe 10GA for about a foot. Then, there's TWO FUSES, one for the positive and one for the negative.
For the life of me, I have never, ever seen a fuse in a ground side set of supply wires to any appliance, much less a radio. And, if you cruise over to the link that was supplied by one of you, that set of power wires for the ICOM 2000, is basically identical to the ones I have, even with a dual set of fuses. Why, may I ask, is there a fuse in the ground wire?
Scott

 

[N5XPM]

Wow,
You guys, as usual, are GREAT! I really appreciate all your experience and help here. Obviously, I've never been, am not now and will not be any form of electrical guru. The stuff's always been over my head. Basic 12VDC stuff is just fine. Super basic 120VAC stuff is fine. But, beyond those two, I'm lost. So, it looks like some say 14-16 ga will work while others, surely stipulate the use of 10GA for my application. I buzzed through the owners manual for the ICOM 2000 and couldn't find any specs on wiring setup.
One more thing, the power wires that emerge from the radio, clearly are not 10GA. They're much closer to 12GA or 14GA. But, that's for only about 6" or so. Then, there's a square duplex plug. On the other side of that plug, appears to be 12GA or even maybe 10GA for about a foot. Then, there's TWO FUSES, one for the positive and one for the negative.
For the life of me, I have never, ever seen a fuse in a ground side set of supply wires to any appliance, much less a radio. And, if you cruise over to the link that was supplied by one of you, that set of power wires for the ICOM 2000, is basically identical to the ones I have, even with a dual set of fuses. Why, may I ask, is there a fuse in the ground wire?
Scott

Fused negative is a “best practice”
If current flows from the battery through the power cord and through the radio case to another load in the vehicle and there is no fuse the result is not good.
Most likely when the main ground wire connection is corroded or otherwise ineffective.

I have seen it happen and it was new radio time.
Fusing closest to the battery is best.
Less expensive than a new radio as well.

 

[mmckenna]

Using larger gauge cable is OK, nothing wrong with it.
The benefit of using a larger gauge wire is that there will be less voltage drop through the wire.
It also makes it so if you want to add more loads later on, you have a bit of headroom in your power feed.

Voltage drop won't be an issue in a mobile install where your power run is so short. A 1 volt drop will not impact the radio. Your vehicle battery should show somewhere around 13.8 volts or so. Maybe a bit higher if the engine is running. Even if you knock off one volt, 12.8 is still plenty for the radio to operate as designed. That voltage drop would be while the radio was transmitting, worse case scenario, etc.
Going larger on the wire size won't hurt, so if you want to spend the few extra cents for the bigger cable, go for it. If you've got enough 14 gauge sitting there ready to go, use that.

Adding more loads would be a decision you'd need to make. If you ever plan on adding a scanner, CB or similar, having a bit of headroom on that cable would be welcome, although you'd want to add a fused distribution block inside the vehicle to distribute power to the Icom, and other radios. You'd need to look at what your future plans are and if it's necessary.

I never understood Icom's logic behind putting the fuses so close to the radio. As was mentioned above, they need to be close to the battery to protect the cable run. Putting them close to the radio and none at the battery leaves a lot of wire exposed to potentially catastrophic issues.

Fusing both leads is common, but doesn't happen with all radio brands. Seems to vary. It won't hurt.

So, it's really up to you. I'd absolutely say do not use anything less than 14 gauge. Use larger wire if you want.

 

[mrweather]

My understanding was if you're wiring the negative lead to the battery you fuse it. But if you're wiring the negative lead to a chassis ground you don't.

And of course, the positive lead is always fused.

 

[mmckenna]

My understanding was if you're wiring the negative lead to the battery you fuse it. But if you're wiring the negative lead to a chassis ground you don't.

Negative for the radio shouldn't be run to the battery.
1. It addresses the corroded ground cable drawing power through the radio issue.
2. Many newer vehicles use a current sensor on the negative lead to monitor power consumption and grounding to the negative battery post can cause issues. The newer manufacturer install/upfitter guides specifically say not to do this.
3. Grounding to the chassis close to the radio works as a return connection to the battery as well as provides a nice RF ground for the radio.

 

[FIREUP]

Again,
I want to thank you all for helping here. I'm gonna try the 14 GA route 'cause, I had plenty on a brand new roll of both red and black. As I stated earlier, the first 6=7" emerging from the back of the radio, seem to be about 14GA anyways. My run, as close as I can figure it, is gonna be very close to about 7'-8' long. The radio is mounted, just in front of my C/B, which is mounted very close to the ceiling of the Jeep, just above and in front of my center rear view mirror. With the new ICON in front of it, I still can see all the dials and channel display on the C/B and, the HAM is not so far back that I can't see the dials, buttons and display on the front of it. It's all perfectly visible. So, the run of the power wire(s) is only a foot or so at the ceiling, then it turns right and heads along the top of the windshield (under a plastic facade) and then turns vertical down the right side of the windshield. Then, it slips between the dash and side pillar, to under the dash where, It heads to the firewall. Through the fire wall and, about a foot away are the battery posts. So, again, all in all, about 6'-7' total.

I've got a brand new antenna, cable, NMO outside fitting, PL-259 and reducer for the inside fitting and, 30' of RG8-X cable. At least I think it's RG8-X since the guy at HRO in San Diego setup all the order so, I figure he kinda knows what he's doing and, if he says I need a reducer due to the smaller sized cable, for the PL-259, I'm assuming I'm getting the RG8X. It will all be in tomorrow, the 28th, yahooo!! We're heading out Jeepign in the morning so, I won't get to this 'till later. Boating on Friday so, maybe Saturday I'll dive into this project.
Scott

 

[mmckenna]

Sounds good.
14 gauge will be fine for that radio.

 

[jwt873]

It's academic at this point, but for the heck of it, I did a quick look and see that Icom specifies a 10.5 Amp draw on full power transmit for the IC-2000 http://www.icom.co.jp/world/support/download/manual/pdf/IC-2000_H.pdf

 

[mrweather]

Negative for the radio shouldn't be run to the battery.
1. It addresses the corroded ground cable drawing power through the radio issue.
2. Many newer vehicles use a current sensor on the negative lead to monitor power consumption and grounding to the negative battery post can cause issues. The newer manufacturer install/upfitter guides specifically say not to do this.
3. Grounding to the chassis close to the radio works as a return connection to the battery as well as provides a nice RF ground for the radio.

Thanks for the info. I only mentioned the fused negative lead situation because it seems all the ham radio manufacturers say in mobile installation to run both positive and negative to the battery.

My current vehicle is a 2018 Dodge Charger and the owner's manual specifically instructs when installing two-way radio gear to run the radio negative to the car chassis and NOT the battery negative. I did just that when I installed my FTM-400XDR (also helps that the battery is in the trunk so nice, short power leads!)

 

[mmckenna]

Thanks for the info. I only mentioned the fused negative lead situation because it seems all the ham radio manufacturers say in mobile installation to run both positive and negative to the battery.

I've mostly been disappointed with amateur radio manufacturers install guides. They're usually lacking….

And some of the amateur radio installs I've seen are truly that, amateur. I've seen some scary installs in my day. Often very little thought goes into them. I usually try to avoid commenting when I see install photos on this site. On the other hand, I've seen some people do some really nice jobs of putting radios in their own vehicles. Really just takes a bit of time, planning and research. Not hard to do.

 

[FIREUP]

Ok Gang,
Again, I want to thank all here for your help and expertise. I just completed the install of the radio and did run the negative lead all the way to the battery. I did so because the ICOM manual shows a picture of both leads going to the battery. And two, we discussed this before but, that manual also shows a fused NEGATIVE lead. And three, the replacement leads for an ICOM come with TWO FUSES attached, one on each lead. And, I'd have to look around but, the ICOM is not the only one that has shown a fuse on the negative lead. There was at least one other brand that had the same situation.

In my order for parts/equipment to do a complete install, I ordered an NMO connector for the antenna end of the cable, a PL-259 for the radio end of the cable, 30' of RG8X cable and, a reducer for that particular sized cable where it enters the PL-259. And, since that particular radio is only a VHF radio, my consultation with the HRO help in San Diego revealed that I should only order a VHF antenna. So, I got one of those, with an NMO base. Well, in looking up how to connect a PL-259 to the coax cable, youtube has a good 1/2 dozen videos showing various ways of connection. But, for the life of me, I can't find ONE WAY on youtube or any other source for that matter, that shows how to connect the NMO to the cable. I finally resorted to the instructions that came with the connector.

I had/have instructions for the PL-259 too but, I like watching someone do it and that gives me a better handle on my approach. I've done that end. Now, it's time for the antenna end. Thanks again for all your help here. Very, very much appreciated.
Scott

 

[jeepsandradios]

Normally you purchase the NMO mount on the antenna cable. In a JK there should be no need for anything longer than the standard cable.

 

[FIREUP]

"In a JK there should be no need for anything longer than the standard cable".

That's a matter of opinion. It all depends on about a 1/2 dozen variables.
1. Where is the radio to be located
2. Where is the antenna to be located
3. What obstacles are there in routing the cable?
4. What complications are in the entire setup?

There may be more. If one is gonna mount a C/B or, a HAM on the floor, beside the passengers left leg which, I've seen multiple times, and the antenna is mounted on one of the front fenders which, I've seen multiple times, then yeah, you'll need about 6' - 8' if coax. If one is gonna mount the C/B or HAM on the drivers side tunnel, which, I've seen, and the antenna is near the drivers side front fender, then again, one needs only a few feet of coax.

But, I'm not one for COMPROMISE! I didn't and don't, want any radios interfering with the comfort of the ride or, sacrificing leg room 'cause I was lazy in mounting any of them. My C/B, A FULL SIZED ONE, not one of those tiny, pain in the a... Cobra 75 models where everything is in the mic, (which I've had three of and all three were junk), is mounted right in front of and above, the rear view mirror. It's mounted via custom contoured 1/8" steel bracket that I designed to contour with the ceiling. I still have access to the twist locks for removing the two tops.

The recently mounted HAM ICON 2000, is mounted directly in front of that C/B. Now, we (the wife and I) NEVER, EVER take the top off or, the two front tops of our JK so, I came up with this idea of a different style mount for the ICOM. I was gonna screw the mounting bracket to the ceiling of both sides of the front two top sections. But, I thought I'd try something "Outside the box". I used industrial "Dual lock" 3M velcro. It's double contact, mushroom head design. That is, it's not your junk "hook and loop" plastic - fuzzy crap. The stuff I used, is like gluing the mount to the ceiling with epoxy. It doesn't move, even with rough off roading.

Enough of that. Now, based on where that radio is located, and, the fact that I had to mount the antenna on the right side of the tail gate because, I wanted it in the BACK OF THE JEEP, not anywhere on the side or front. The CB antenna is on the left side of the spare tire and routing that cable to the C/B radio took almost every inch of the 17' of cable that came with my order. And, it's been stated in more than a few HAM installation instructions, TO NOT RUN THE ANTENNA CABLE NEXT TO OTHER CABLES.

So, with all that being said, I calculated the length of need for that new antenna to be a minimum of 22' -25'. Well, I ordered 30' RG8X cable/coax, JUST TO MAKE SURE, I was covered in this scenario. The CB coax was ran from the tailgate, adding a loop for tailgate swing, and then, up into the padding for the roll bar, all the way to the windshield. But, the coax fo the HAM, needed to be ran along the floor, along the door sills and all the small obstacles along the route, to the kick panel on the passenger's side. Then it had to snake its way up, alongside the right side of the dash, up the pillar to the windshield, along the right side upper windshield and turn left, and head for the ICOM.

When it was all said and done, and completely finished, of the 30' of RG8X coax I ordered, I had THREE FEET LEFT OVER!!!!


So, your statement of a JK having no need for a standard cable length, was a bit off. Sorry for the long speech here but, I wanted to explain why I needed that EXTRA length of cable for my particular run.
Scott

 

[PrivatelyJeff]

I never understood Icom's logic behind putting the fuses so close to the radio.

So you can trim off excess wire and still be fused.

 

[FIREUP]

So you can trim off excess wire and still be fused.

But, even after trimming excess wire, your fuses might still be quite a distance from the power source. And that presents a potential problem Very, very much of the auto industry fuses all its circuits fairly close to the battery. If they don't, then many of them have a fusible link at the main power wire from the battery to the fuse panel for protection of that power wire. At least that's the way I've seen many of them.
Scott