A-frame Nav Lights - Wiring Q ??!

[Pikey Dave]

Originally Posted by Last Tango

Don't try to wire a boat like a house, That's not is how it's done in your outboard. Why double the cable length when you're still going to have to join it somewhere.

But houses don't fizz away to nothing in salty water. Start using the boat metalwork as a main conductor & you will introduce all sorts of weird stray currents. Before you know it, you'll be getting shocks off the A frame & your anodes will fizz away to nothing & drop off[emoji15] Metal work should be earth bonded to prevent this from happening. Many vehicle electrical faults are a result of a "bad earth".

[Last Tango]

Thirty year old outboards out there (and they're aluminium not stainless) that haven't fizzed away. "Stray currents"? You'd have to be much more detailed in exactly what covalent potentials you think would arise and how you'd find any comparison with a mild steel car relevant.

By grounding the "A" frame it bonds the entire system and gains protection from the engine zinc anodes. They may degrade marginally quicker but it's infinately better than having 30ft of cable you don't need.

My "A" frame is wired like this...absolutely no issues whatsoever, and never had an issue with any boat previously.

[Pikey Dave]

Originally Posted by Last Tango

Thirty year old outboards out there (and they're aluminium not stainless) that haven't fizzed away. "Stray currents"? You'd have to be much more detailed in exactly what covalent potentials you think would arise and how you'd find any comparison with a mild steel car relevant.



By grounding the "A" frame it bonds the entire system and gains protection from the engine zinc anodes. They may degrade marginally quicker but it's infinately better than having 30ft of cable you don't need.



My "A" frame is wired like this...absolutely no issues whatsoever, and never had an issue with any boat previously.

But outboards are earthed straight back to the battery with a honking big cable, not earthed via the A frame, so I'm confused as to what you're advocating here[emoji848] I'm also agreeing that the A frame should be bonded, as should all the other major metal components, what I wouldn't do is then use the A frame as an earth point for electrical kit such as lights etc. When you read the installation instructions for electrical kit, most will tell you to earth to the boat's main earth point or earth plate. As I understand it, you are saying that you would earth the A frame & then use that as the earth point for electrical kit, is that correct?

[Last Tango]

Yep.
Ground the "A" frame directly to the battery -ve terminal. It is then grounded and bonded to the engine by the -ve cable. "It's "earthed" via the water. (Would be better directly connected to an external zinc but not that practical and a lightning strike could leave you with a hole in the boat.) but in the unlikely event of any residual current leakage, that will take care of it. You're not going to get a shock off it. Remember this is 12V dc and your impedance is predominantly capacitative rather that resistive.....you don't get a shock (other than static) from the body of a car.

Sorry I'm rambbling, yes I'd ground the "A" frame mounted kit to the "A" frame and minimise the impedance on the return leg. (I do, incidentally, use very heavy cable to ground the "A" frame....6mm).

[Pikey Dave]

Originally Posted by Last Tango

Yep.

Ground the "A" frame directly to the battery -ve terminal. It is then grounded and bonded to the engine by the -ve cable. "It's "earthed" via the water. (Would be better directly connected directly to an external zinc but not that practical and a lightning strike could leave you with a hole in the boat.) but in the unlikely event of any residual current leakage, that will take care of it. You're not going to get a shock off it. Remember this is 12V dc and your impedance is predominantly capacitative rather that resistive.....you don't get a shock (other than static) from the body of a car.



Sorry I'm rabbling, yes I'd ground the "A" frame mounted kit to the "A" frame and minimise the impedance on the return leg. (I do, incidentally, use very heavy cable to ground the "A" frame....6mm).

Hmm! Not the way I'd do it, but each to their own. [emoji106]

[Erin]

Originally Posted by Last Tango

By grounding the "A" frame it bonds the entire system and gains protection from the engine zinc anodes. They may degrade marginally quicker but it's infinately better than having 30ft of cable you don't need.

I can't see why your anodes would deplete faster by bonding them to your A-frame. There is no electrolyte between your frame and anodes so there could be no PD to cause wastage. I cannot see any advantage in bonding an A-frame as it is a standalone metal item in most cases and at minimal risk of corrosion. If anything you could introduce a problem if a nave light wire chafes and contacts the frame. Better to be isolated IMHO.

Originally Posted by Pikey Dave

I'm also agreeing that the A frame should be bonded, as should all the other major metal components, what I wouldn't do is then use the A frame as an earth point for electrical kit such as lights etc. When you read the installation instructions for electrical kit, most will tell you to earth to the boat's main earth point or earth plate.

Lets be careful not to confuse bonding/earthing with the negative side of a power circuit. Unless you have a 240v shorepower installation on your boat, bonding of above water metal components is pointless. If anything it might introduce a problem. I would also be cautious of using any metal component as the return path for electrical units as there is a risk of corrosion at the interface between the wire/crimp and the metal component. Why introduce an interface and potential impedance to the circuit.

[Pikey Dave]

Originally Posted by Erin

I can't see why your anodes would deplete faster by bonding them to your A-frame. There is no electrolyte between your frame and anodes so there could be no PD to cause wastage. I cannot see any advantage in bonding an A-frame as it is a standalone metal item in most cases and at minimal risk of corrosion. If anything you could introduce a problem if a nave light wire chafes and contacts the frame. Better to be isolated IMHO.







Lets be careful not to confuse bonding/earthing with the negative side of a power circuit. Unless you have a 240v shorepower installation on your boat, bonding of above water metal components is pointless. If anything it might introduce a problem. I would also be cautious of using any metal component as the return path for electrical units as there is a risk of corrosion at the interface between the wire/crimp and the metal component. Why introduce an interface and potential impedance to the circuit.

I agree absolutely wrg using metal lumps as return paths. Re. Bonding, I've had cases where either faulty wiring or water ingress has caused the A frame to become live, only to the point where you get a 12V tingle if you touch it with wet hands, not a problem per se, but I don't want stray currents wandering around the boat. At least if the metalwork is bonded to earth, any fault should pop a fuse & alert me to a problem.

[Last Tango]

Originally Posted by Erin

I would also be cautious of using any metal component as the return path for electrical units as there is a risk of corrosion at the interface between the wire/crimp and the metal component. Why introduce an interface and potential impedance to the circuit.

Someone better tell your engine manufacturer then, because every electrical component in there will be wired this way. The original concept of a -ve ground was that it would provide cathodic protection but the jury's out on that one.

You are going to have to connect it somewhere (-ve bus bar?) so your "interface" is still going to exist, only you've compounded the resistance by adding 15ft of wire before the connection. As inductive and capacitative impedance don't play any part in this, simple "resistance" is the only factor.

I wouldn't twist someone's arm to do it this way because the difference really is so marginal (going LED would make a far bigger difference than the wiring method) but that's how I've always done it and never had any problems as a result and it certainly makes wiring the lights a lot easier.

[Iron Dials]

Would any of the professionals (in the boat industry- not aviation, cars, trucks, spaceships etc.) on the site like to tell what is required for a new build?

Assuming this is the standard any retrofit should be shooting for?

It's clear there are at least 2 successful ways of doing this, I'm just wondering which one could be stood over as correct, in the professional or insurance survey sense.

And sorry, I don't mean to insult or wind up anyone who has taken the time to post useful info here.

[GuyC]

Originally Posted by wookie 1

I know this is an old thread, but trying to avoid unnecessarily create new ones. I get parallel vs series, but not sure how best to wire the a frame to achieve this with port and starboard. I will then keep the white on a separate circuit/switch as suggested.

Also, how best to feed wire through a frame/pull out at the relevant points?

My boat has a junction box mounted on the inboard side of the plate on which one of the side lights is mounted. There are two positive feeds for side lights and masthead light with one negative return wire. These go into a chocolate block connector in the junction box and then each light is fed by a positive and negative back to the junction box.

You can get nylon cable pullers that you can tape the ends of the wire to to pull them through. Feed the puller all the way through the route before attaching the cable. If you wrap tape around the cable first before going around the puller it reduces the chance of the cable sliding along the puller.

Where the cable exits the A-frame, put a grommet in the hole to stop chafing.

I use WD40 or silicon spray to make pulling the cables easier.

[Poly]

Originally Posted by Iron Dials

Would any of the professionals (in the boat industry- not aviation, cars, trucks, spaceships etc.) on the site like to tell what is required for a new build?

The wiring on many new build boats is shocking so I don't think you can hold that up as the gold standard!

[Iron Dials]

"Shocking" brilliant

[Erin]

Originally Posted by Last Tango

Someone better tell your engine manufacturer then, because every electrical component in there will be wired this way. The original concept of a -ve ground was that it would provide cathodic protection but the jury's out on that one.

Agreed, but we are dealing with a slightly different situation on an engine. You find me a spark plug that is not 'earthed' by the cylinder head. Marine outboards have inherited their design from car and motorbike engines. There is no alternative way to wire them without a very specialist redesign which would surely be cost prohibitive.

Originally Posted by Last Tango

You are going to have to connect it somewhere (-ve bus bar?) so your "interface" is still going to exist, only you've compounded the resistance by adding 15ft of wire before the connection.

But at least you can locate your 'interface' in a protected location such as a console where it will be away from the worst of the weather and salt spray.

[Last Tango]

A note to the OP who is now in a state of alarm and confusion........
We are standing on soap boxes firing peas at one another..

This isn't going to make a lot of difference one way or another.

The important things....make sure any drill burrs are cleared out the holes and the wires properly protected where they go through them. If you can, go for LED lights (Low current and reliable). As for wire gauge....the current draw is minimal so don't base it on that, think about the mechanical strength because that's more likely to cause a failure than any "overload".

[beerbelly]

rock on to many mountains made out of molehils

[Pikey Dave]

Originally Posted by beerbelly

rock on to many mountains made out of molehils

You see mountains & molehills, I see open discussion & an exchange of ideas and experience. The OP now has a wealth of info on which to make an informed decision. Which is the point of a umm err "forum"! All my IMHO of course[emoji6]

[GuyC]

Originally Posted by Iron Dials

Would any of the professionals (in the boat industry- not aviation, cars, trucks, spaceships etc.) on the site like to tell what is required for a new build?

Assuming this is the standard any retrofit should be shooting for?

It's clear there are at least 2 successful ways of doing this, I'm just wondering which one could be stood over as correct, in the professional or insurance survey sense.

And sorry, I don't mean to insult or wind up anyone who has taken the time to post useful info here.

As I'm going to be rewiring my boat over the winter, I thought I'd try and find out.

The workboat code which can be found via Google gives guidance for commercially operated vessels. The Recreational Craft Directive (not freely available) gives guidance on vessels built for recreational purposes.

I'm only dealing with low voltage DC systems - 12V or 24V.

The workboat code says that DC circuits should be two conductor i.e. feed and return. The exception to this is for engine circuits where return connections can be made on the engine itself. Metallic objects that do not have good continuity with the water should be earthed.

The RCD goes into a bit more detail and breaks up the two conductor circuit into entirely isolated and a two conductor circuit with negative ground.

It specifically says the hull should not be used as a current carrying conductor.

In summary I would suggest having a two wire system with a non current carrying negative ground that your significant metallic objects are grounded to.

I wouldn't use the A-frame or other metal parts of the boat as a current carrying conductor (except the engine for the engine circuit).

In searching for stuff I came across the site below which is a checklist for inspectors looking at RCD vessels.

https://www.imci.org/userfiles/other...20en160122.pdf

I'm not an electrician so the usual caveats apply.

[Pikey Dave]

Originally Posted by GuyC

......



The workboat code says that DC circuits should be two conductor i.e. feed and return. The exception to this is for engine circuits where return connections can be made on the engine itself. Metallic objects that do not have good continuity with the water should be earthed.



The RCD goes into a bit more detail and breaks up the two conductor circuit into entirely isolated and a two conductor circuit with negative ground.



It specifically says the hull should not be used as a current carrying conductor.



In summary I would suggest having a two wire system with a non current carrying negative ground that your significant metallic objects are grounded to.



I wouldn't use the A-frame or other metal parts of the boat as a current carrying conductor (except the engine for the engine circuit).

[emoji106]+1 which is more or less what was said yonks back & what some of us instinctively knew was right, but at least you now have the official version.

[Iron Dials]

Thanks for that GuyC.
I just bought a few books last winter and they all agreed with this, which as PD says is what most would expect to do anyway.