Wire choice for float and bilge pump

[Refueler]

Working fine isn’t necessarily the only measure of success. The outcome would be a potential fire risk as resistance increases, and this by its nature means it would work right up until the fire.
Not saying that’s the case, just highlighting that bad things can work and still be bad things.

I can have fire from engine ... cooker ... heater ..... all sorts ...... I can step / fall of the boat ... so many hazards ... far more realistic than the resistance scenario ..

And I reckon - I am far from only person who's done it ... despite all the expert dire consequences risked !!

 

[lustyd]

I never said you were at risk, I said that your assertion that it's working so it's fine is flawed.

 

[Alex_Blackwood]

Working fine isn’t necessarily the only measure of success. The outcome would be a potential fire risk as resistance increases, and this by its nature means it would work right up until the fire.
Not saying that’s the case, just highlighting that bad things can work and still be bad things.

How would you get a fire risk with increased resistance

 

[Refueler]

How would you get a fire risk with increased resistance

I wasn't going to argue the point ... as untinned wire will usually go black and lose connectivity ...

 

[PaulRainbow]

I'm not concerned about a fire risk, it's just a bodge that makes it unreliable. That's the wire choice and the connectors.

 

[Refueler]

I'm not concerned about a fire risk, it's just a bodge that makes it unreliable. That's the wire choice and the connectors.

I know - some people like to expand the subject !!

 

[lustyd]

How would you get a fire risk with increased resistance

The Watts being pulled remain static, with increased resistance the voltage will drop so the Amps ramp up and the wire gets hot. With luck there would be a fuse to stop this happening and the worst that would happen would be systems failing. Given we're talking about a bodge though, there might not be a fuse in there.

If you want to try this, put a single strand of copper between your battery and something on the boat and see if it stays cool

 

[PaulRainbow]

The Watts being pulled remain static, with increased resistance the voltage will drop so the Amps ramp up and the wire gets hot. With luck there would be a fuse to stop this happening and the worst that would happen would be systems failing. Given we're talking about a bodge though, there might not be a fuse in there.

If you want to try this, put a single strand of copper between your battery and something on the boat and see if it stays cool

What if the single strand of copper is 2.5mm sq and the load is a small LED light, 3w ?

 

[Refueler]

What if the single strand of copper is 2.5mm sq and the load is a small LED light, 3w ?

How longs a piece of string ...

C'mon guys .. lets be sensible here .... I used what is not recc'd ... its lasted 20yrs .... so I'm guilty as charged. Isn't that good enough ?

To start this 'fire' bit is IMHO OTT.

 

[ChromeDome]

If best practices are no more difficult and cost no more than a redneck DIY, why not eliminate risk, improve value and get a better gut feeling?

 

[Fr J Hackett]

How longs a piece of string ...

C'mon guys .. lets be sensible here .... I used what is not recc'd ... its lasted 20yrs .... so I'm guilty as charged. Isn't that good enough ?

To start this 'fire' bit is IMHO OTT.

And you complained about the wiring on your new boat

 

[justanothersailboat]

I think a fire is technically possible but really unlikely, whereas falling performance is very likely. I've seen untinned wire build up corrosion inside and the voltage at the end drops, then you get dim lights and feeble motors, or LEDs that suddenly won't light at all, etc. When amending an existing system you have to pick your battles (few indeed are the older boats with perfect, flawless electrics!). However, it's not much more work and cost to head off a risk of things going flaky in an unpredictable timeframe by choosing good materials and making good connections for the bits you do do.

I suspect a lot of how long the stuff lasts depends on how dry your particular boat is and maybe exactly where and how it's kept.

 

[Refueler]

If best practices are no more difficult and cost no more than a redneck DIY, why not eliminate risk, improve value and get a better gut feeling?

Oh don't you start as well ...

Come over here and try find the gear ... its not UK or USA ... we often have to do with what we can source here.

 

[Refueler]

And you complained about the wiring on your new boat

Different matter all together ... even my crap wires on Superanne can be identified / traced.

But on Anisette - different altogether ...

 

[lustyd]

then you get dim lights and feeble motors, or LEDs that suddenly won't light at all, etc

That's just the noticeable effect of the voltage dropping, the wire is very probably getting hot in the degraded part too. Same as if you screw a choc block too tight and break a bunch of strands.

What if the single strand of copper is 2.5mm sq and the load is a small LED light, 3w ?

Are you advocating for solid core now?

 

[Refueler]

In the Red corner we have .......

and In the Blue corner we have ....

Seconds Out - Round ....

 

[PaulRainbow]

That's just the noticeable effect of the voltage dropping, the wire is very probably getting hot in the degraded part too. Same as if you screw a choc block too tight and break a bunch of strands.

Are you advocating for solid core now?

Anything goes, it seems

 

[justanothersailboat]

Wish I'd got this handy thermal imaging camera BEFORE I completely rewired my boat. It could have won some arguments. As it is, it just tells me I don't have any hot joins.

lustyd - I agree the wire adding resistance and causing voltage drop is the same as it dissipating electrical energy as heat, I just don't expect the wire to actually get hot for most boat loads from corrosion alone. The 4 A or so of a bilge pump x 3v of volt drop is the wire working as a twelve-watt heater, could well be one watt per foot on a reasonable sized boat. Bad, but not incendiary. If you have the same drop just in one bad JUNCTION on the other hand you will melt things.

 

[lustyd]

Oh I agree, but then it depends how long you allow the corrosion to go on for and if you notice. Eventually that corrosion will eat most of the wire.

 

[justanothersailboat]

Yes, it's ghastly when you strip the stuff and it's black for much of the length!

I think there are decent odds that a good heatshrink crimp on each end of an untinned wire would make it last a long time, since salty water wicking up the strands seems to be a big part of the problem, but I haven't tried this.