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Old 21-11-2020, 16:15   #16
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Re: what AWG for mast head light?

Practically he is speaking of no load with an LED. Things can be over thought. I would be concerned with the wire mechanically up and down the mast. AWG 22 would probably be fine electrically.
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Old 22-11-2020, 06:51   #17
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Re: what AWG for mast head light?

I'm all for going with the higher rating on critical function stuff, but this discussion has kinda gotten off into the weeds. ABYC specs are the gold standard. 14g is a bit of overkill, which is the way to go.
Keep in mind that, unless this is a wood or carbon fiber mast, a metal mast will serve as a negative return as it is bonded to the boat's overall common ground. So I would tie it into the light's ground at the top, leaving the positive side as the real issue, voltage drop wise and keep the negative return wire running down as well. A belt and suspenders approach.
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Old 22-11-2020, 08:41   #18
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Re: what AWG for mast head light?

Were I to rewire my mast, I’d go with likely a 5 strand probably 16Ga wire.
Quality LED’s as stated will operate fine over a wide range of voltage and it’s rare for one to draw over 1 amp per bulb.
I had an idiot “professional” boat electrician rewire mine, every light has its own I believe 14Ga wire and ground. You couldn’t stuff another wire in the conduits, and likely due to there being so much wire in them, they came loose from the mast.
The five strands would give you the capability to operate 4 lights, anchor, tricolor, steaming and deck light. Spreader lights may draw enough current to require their own larger gauge wire depending on what you choose.

Do NOT go with lower quality LED’s, you will be sorry if you do, I have been very happy with Marine Beam, not so much with my Aqua Signal tricolor, it’s just not very bright, it’s legal of course, just wish it were brighter.

Many, many LED’s are very noisy radio wise

I would not use the mast as a ground myself due to concern of stray current.
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Old 22-11-2020, 09:19   #19
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Re: what AWG for mast head light?

As mentioned earlier, 14 AWG minimum for a lighting circuit (assuming US boat)

https://www.law.cornell.edu/cfr/text/46/183.340

From a pure 'electrical' standpoint, OP's 5W LED (12.7v x .394a) would pass a <3% voltage drop with 18 AWG at 70' from panel and as also mentioned if it is variable input voltage LED it should compensate for variable supply voltage, but if it can compensate then it needs to be checked for 'noise' aka EM interference...

Who would have thought it'd be so crazy to wire one anchor light ?!?
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Old 22-11-2020, 09:21   #20
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Re: what AWG for mast head light?

Quote:
Originally Posted by patrick brooks View Post
not to start A recalculate moment but new Led light are 4 to 24v so I think they are not as VD sensitive , wiring should be sized to support a standard incandescent , my led mast head sure creates a lot of radio interference RF I think fair winds
Quote:
Originally Posted by Jim Cate View Post
Just a comment: most modern LED lights have on-board circuitry that claim full light output at voltages from (typically) 10-30 VDC. This being the case, worrying about small voltage drops seems unnecessary.

Jim
Quote:
Originally Posted by duckpond49 View Post
I'm all for going with the higher rating on critical function stuff, but this discussion has kinda gotten off into the weeds. ABYC specs are the gold standard...
And this discussion perfectly reflects the problem standards have in keeping up, and not allowing for sound engineering. The standard takes so long to modify that it can’t keep up. The standard reflects a time when most “12V” bulbs, for instance, were actually designed to run at 13.8V because they were borrowed from the automotive industry where the alternator is always available. In that world a 3% drop from batteries at resting state makes a ton of sense. SSB radios are another good 13.8V example.

I’d still go with 14AWG for mechanical reasons, but if the LED specs say you can run at 10V then the standard shouldn’t be quite so focused at the 3% voltage drop if it allows 10% in other loads (personally I would almost never suggest/engineer 10% for a high use load because that’s a waste of too much precious electricity heating wire, but that’s an engineering decision, not a standards driven one).
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Old 22-11-2020, 10:06   #21
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Re: what AWG for mast head light?

An outside thought. Some of the masthead lights are 'two wire.' In some situations a tiny $10-15 inline 12v to 24v converter (if indeed the LED is too voltage sensitive) down low might save scant weight aloft/save $ using smaller wires, though clearly another failure mode (converter) introduced and too-small of wire mechanically maybe not safe as mentioned up-thread.
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Old 22-11-2020, 10:17   #22
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Re: what AWG for mast head light?

As part of a mast refit on a Catalina 28 we replaced the wire, and anchor light (among other things). From mast head to cabin sole it was in the 46’ range + in cabin wiring.

The original wiring was 16 gauge and had been serviceable for many years, but eventually failed due to cracked insulation.

Like the OP I decided to upgrade the wire size, in my case 14 (multi-strand tinned copper 14x2). It was a little snugger in the mast conduit but still allowed the installation of a masthead wind transducer cable. The only problem is where the wire exited the mast and then entered the anchor light fixture.

On this boat the internal wire entered the mast head through a hole, then a stainless steel washer. A knot in the wire sitting on the washer was strain relief. Not surprisingly this is where the insulation failed causing a short. Since the boat was 29 years old I felt that the solution was adequate.

The larger wire size made tying the knot difficult. I also struggled with the tight turns required inside the anchor light fixture.

The long winded point is there are other considerations. Larger wire made the final connections not quite as clean and much more difficult. The new LED fixture was order of magnitude brighter and would have been just fine with 16 gauge wire. When doing upgrade work on my older boats I review the current ABYC standards and upgrade if needed. That said, If I were to do it again I would match the #16 wire size that was in the mast. Quality LED's are brighter and function better with a little voltage drop.

I’d also add that wire/conduit lubricant is your friend.
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Old 22-11-2020, 10:54   #23
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Re: what AWG for mast head light?

I am compelled to respond to the notion that LED's are noise sources. They are NOT when used as straight DC lighting. As an electronic tech, I keep running into this notion.
It is propagated by confusion, primarily with dimmable interior lighting, which uses high frequency switching to achieve the dimming function. This is from ledbenchmark.com:

"While the Light Emitting Diodes themselves do not generate any detectable noise, the switching power circuitry driving the LEDs operate at high frequencies, which, when not properly filtered can result in electromagnetic interference."

Led's are used in various onboard electronics without RF propagation: VHF, Sideband, data displays, etc.
I love my dimmable LED interior lighting. I just found some great lighting (not marine specific) that allows a dimmer to be easily plugged in, in-series, to handle dimming. So while at anchor or on shore power I dim freely. When I am underway and need to trust my instrumentation I sacrifice the luxury of dimming.
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Old 22-11-2020, 11:05   #24
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Re: what AWG for mast head light?

When I did my mast rewiring I built my own custom wiring harness, mostly because the 5 conductor stuff is crazy expensive and you have to cut it part way for the spreader lights etc.

I built mine by laying out a single 12awg conductor for the ground with a spliced in pig tail for the spreader level devices. then layed out individual conductors for the anchor, spreader, steaming light etc. After that I grabbed some 5/32 rope and ran that the entire length with occasional hitches to keep the bundle together, Wrap the whole thing in the cloth wire harness wrap (looks like hockey tape) and that's it. the rope supports the wire the full length. To get the harness inside the mast I attached 2 lines (one to the top and one to the mid point where it comes out the mast, then had someone help me pull the whole thing into the conduit in the mast. worked pretty good for me. This way I can also size each conductor to the needs of the device, though in practise I used 16 awg for most of it except the spreader light which was 14awg

been working great for several years.
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Old 22-11-2020, 11:31   #25
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Re: what AWG for mast head light?

I doubt a mast head light is a 5W LED, 1W is an awful bright LED.

5 strand 16 ga cable $1.26 a foot
https://www.showmecables.com/16-awg-...xoC8hUQAvD_BwE

However thats 5 cables worth, if run in individual wires, your buying five times as many feet of wire, when you price that your way ahead even if you want tinned “marine” wire.

physical strength wise, a 5 strand wire is awful strong.
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Old 22-11-2020, 11:48   #26
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Re: what AWG for mast head light?

Quote:
Originally Posted by duckpond49 View Post
I'm all for going with the higher rating on critical function stuff, but this discussion has kinda gotten off into the weeds. ABYC specs are the gold standard. 14g is a bit of overkill, which is the way to go.
Keep in mind that, unless this is a wood or carbon fiber mast, a metal mast will serve as a negative return as it is bonded to the boat's overall common ground. So I would tie it into the light's ground at the top, leaving the positive side as the real issue, voltage drop wise and keep the negative return wire running down as well. A belt and suspenders approach.
My mast is only bonded to my lead keel.
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Old 22-11-2020, 11:58   #27
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Re: what AWG for mast head light?

Quote:
Originally Posted by a64pilot View Post
Were I to rewire my mast, I’d go with likely a 5 strand probably 16Ga wire.
Quality LED’s as stated will operate fine over a wide range of voltage and it’s rare for one to draw over 1 amp per bulb.
I had an idiot “professional” boat electrician rewire mine, every light has its own I believe 14Ga wire and ground. You couldn’t stuff another wire in the conduits, and likely due to there being so much wire in them, they came loose from the mast.
The five strands would give you the capability to operate 4 lights, anchor, tricolor, steaming and deck light. Spreader lights may draw enough current to require their own larger gauge wire depending on what you choose.

Do NOT go with lower quality LED’s, you will be sorry if you do, I have been very happy with Marine Beam, not so much with my Aqua Signal tricolor, it’s just not very bright, it’s legal of course, just wish it were brighter.

Many, many LED’s are very noisy radio wise

I would not use the mast as a ground myself due to concern of stray current.
Thanks. Its a good light Peters & Bey. Not sure about RF noise. Will be a couple months to install

https://store.offshorespars.com/prod...-light-silver?
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Old 22-11-2020, 12:06   #28
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Re: what AWG for mast head light?

Quote:
Originally Posted by a64pilot View Post
I doubt a mast head light is a 5W LED, 1W is an awful bright LED.

5 strand 16 ga cable $1.26 a foot
https://www.showmecables.com/16-awg-...xoC8hUQAvD_BwE

However thats 5 cables worth, if run in individual wires, your buying five times as many feet of wire, when you price that your way ahead even if you want tinned “marine” wire.

physical strength wise, a 5 strand wire is awful strong.
Thanks fornthe link. Im also adding a steaming/deck light. The anchor lihjt is only 2 wires. The steaming deck liggt combo five wires. A red and black on each and an extra white wire on one of them. Forget which one.

Im worried that 5 strand may notbfit alongside my new LMR Coax cable.
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Old 22-11-2020, 12:10   #29
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Re: what AWG for mast head light?

Quote:
Originally Posted by pcmm View Post
When I did my mast rewiring I built my own custom wiring harness, mostly because the 5 conductor stuff is crazy expensive and you have to cut it part way for the spreader lights etc.

I built mine by laying out a single 12awg conductor for the ground with a spliced in pig tail for the spreader level devices. then layed out individual conductors for the anchor, spreader, steaming light etc. After that I grabbed some 5/32 rope and ran that the entire length with occasional hitches to keep the bundle together, Wrap the whole thing in the cloth wire harness wrap (looks like hockey tape) and that's it. the rope supports the wire the full length. To get the harness inside the mast I attached 2 lines (one to the top and one to the mid point where it comes out the mast, then had someone help me pull the whole thing into the conduit in the mast. worked pretty good for me. This way I can also size each conductor to the needs of the device, though in practise I used 16 awg for most of it except the spreader light which was 14awg

been working great for several years.
Im also installing new coax, LMR-400 UF. i figured i would tape all the wiring to the coax and try and pull it through in one bundle. Fingers crossed. I was planning on simple 2 strand forbthe lights.
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Old 22-11-2020, 12:14   #30
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Re: what AWG for mast head light?

@duckppnd49

I have two types of leds in my cabin. One type, higher quality fixtures produces some noise, the other type produces a lot of noise. It doesnt affect my mast head vhf only my small handheld when im in the cabin with light on. I kept two fixtures in the main cabin wired with old school incandescents just in case.
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