Wiring size

[Firefly]

Originally Posted by Manolism

the length of a boat when we talk about safety It' irrelevant . The spark may cause fire and finally the same result to any boat in an accident. Safety come first in my opinion.

We are not suggesting for 1 minute the length of the boat relates to the safety standard applied. We are talking about lengths of wiring runs and the resulting voltage drop which is not likely to be an issue on a 5M boat. Of course safety is paramount.

[Dirk Diggler]

Originally Posted by Iron Dials

Would you fly on an aircraft where the tech advice came form an internet forum, albeit one as good and helpful as ribnet?

[gtflash]

Here is my cb ratings. vhf and trim tabs were hungry for me.

Bilge 1 5a
Bilge 2 3a
Bilge 3 3a
Vhf 10a
Plotter 5a
Nmea 3a
Nav lights and deck lights 5a
Trim tabs 20a

Max 54a.
Was going to use 25mm cable but my cable length was 6 ish meters. I bought parts from 12v planet and they have a handy little volt drop calculator that meant I jumped up to 35mm supply to whole dis.

Most of my Switches and components are in 2.5 or 1.5mm for short runs.

just to point out. I have been to college and uni and can work all this out myself and I actually work on electrical/electronics daily and see the damage to multi million pound machines caused by incorrect cabling, crimping, excessive joins and generally shoddy workmanship but the calculator is ideal.

I would echo others comments work out your demand, and cable length, punch it in the calculator and sleep well at night. Heat shrink connections with the water proofness, plan a little extra for that new radar or deck lights too. It's not a major effort. Ten minutes of maths.

Cable sizing and selection | 12 volt planet

[Stevem]

Originally Posted by gtflash

Here is my cb ratings. vhf and trim tabs were hungry for me.

Bilge 1 5a
Bilge 2 3a
Bilge 3 3a
Vhf 10a
Plotter 5a
Nmea 3a
Nav lights and deck lights 5a
Trim tabs 20a

Max 54a.
Was going to use 25mm cable but my cable length was 6 ish meters. I bought parts from 12v planet and they have a handy little volt drop calculator that meant I jumped up to 35mm supply to whole dis.

Most of my Switches and components are in 2.5 or 1.5mm for short runs.

just to point out. I have been to college and uni and can work all this out myself and I actually work on electrical/electronics daily and see the damage to multi million pound machines caused by incorrect cabling, crimping, excessive joins and generally shoddy workmanship but the calculator is ideal.

I would echo others comments work out your demand, and cable length, punch it in the calculator and sleep well at night. Heat shrink connections with the water proofness, plan a little extra for that new radar or deck lights too. It's not a major effort. Ten minutes of maths.

Cable sizing and selection | 12 volt planet

Talk about taking a gun to a knife fight. 35mm? Thats hefty cable!

[Pikey Dave]

Originally Posted by gtflash

Here is my cb ratings. vhf and trim tabs were hungry for me.



Bilge 1 5a

Bilge 2 3a

Bilge 3 3a

Vhf 10a

Plotter 5a

Nmea 3a

Nav lights and deck lights 5a

Trim tabs 20a



Max 54a.

Was going to use 25mm cable but my cable length was 6 ish meters. I bought parts from 12v planet and they have a handy little volt drop calculator that meant I jumped up to 35mm supply to whole dis.



Most of my Switches and components are in 2.5 or 1.5mm for short runs.



just to point out. I have been to college and uni and can work all this out myself and I actually work on electrical/electronics daily and see the damage to multi million pound machines caused by incorrect cabling, crimping, excessive joins and generally shoddy workmanship but the calculator is ideal.



I would echo others comments work out your demand, and cable length, punch it in the calculator and sleep well at night. Heat shrink connections with the water proofness, plan a little extra for that new radar or deck lights too. It's not a major effort. Ten minutes of maths.



Cable sizing and selection | 12 volt planet

At the risk of going all "Poly", you missed out the demand & diversity factors from your calcs. The chances of you actually having all your devices drawing current at the same time are virtually nil. Your 2 biggest loads are trim tabs & VHF (on transmit) these are both intermittent loads by nature. I'd doubt that your total load at any one time would exceed 25A.

[Firefly]

Poor Richard N Hunt. He now has to sift through this lot to separate the sh1t from clay. I bet he wishes he had never asked the question...

[Poly]

Originally Posted by Firefly

If doubled up cables make you nervous, don't ever fly again. Doubled up cables are commonly used on aircraft systems.

where presumably they have been engineered in for redundancy rather than to carry extra current because someone was avoiding buying the right size cable in the first place?

Note, I mentioned wire gauges ranging from 20 to 16 awg. A 5 meter rib is unlike to have any system that would present a fire hazard due to loss of 1 of these wires.

you did, and I might be misreading your intent - but you seemed to suggest if concerned about the rating for the high draw equipment to double up the skinny cable - that implies a single length is insufficient.

In any event, if the wires are doubled up and crimped together in the terminal, what are the chances of just one wire corroding and failing?

let me ask the question a different way. If you have a doubled wire with crimped connectors what are the modes of failure? certainly not all will result in both wires being disconnected simultaneously.

One other point. How is electrical failure almost inevitable? I have many hours on RIBS under my belt, most of these, I have rewired entirely from scratch and I have never suffered electrical failure.

RIBs get abused. They live in a highly corrosive environment. They get bounced around. The often get stored in damp conditions. The wiring is frequently not well mechanically installed. "Service" frequently involves the engine and trailer and ignores the electronics. The wiring is often hard to see/inspect. The fact you have rewired most of your ribs supports the case that eventually most "at some point" failure is likely. Am I going to far saying "almost inevitable"? Perhaps. Or perhaps you've been lucky so far. Either way its certainly not a negligible risk that a failure happens - as many people on this forum will be able to attest to.

Originally Posted by Pikey Dave

At the risk of going all "Poly"

[Richardnhunt]

Originally Posted by Firefly

Poor Richard N Hunt. He now has to sift through this lot to separate the sh1t from clay. I bet he wishes he had never asked the question...

Nah - it's all good debate and will help - keep it up :-)

[Pikey Dave]

Originally Posted by Firefly

Poor Richard N Hunt. He now has to sift through this lot to separate the sh1t from clay. I bet he wishes he had never asked the question...

Nah! By the time he's read up to post 5, he has all the info needed[emoji57]

[Erin]

If you are ordering enough then it's worth the postage to get Ancor Marine cable and crimps from GenuineDealz in the US. Even with postage it was cheaper than UK sources. I wired my rib with Ancor products and have not had any electrical failure in 9 years. Never use anything other than tinned cable and always use adhesive lined heatshrink. If you are going to the effort of a re-wire you may as well do it properly.

[Firefly]

Originally Posted by Pikey Dave

Nah! By the time he's read up to post 5, he has all the info needed[emoji57]

Indeed he does...

[Firefly]

Originally Posted by Poly

where presumably they have been engineered in for redundancy rather than to carry extra current because someone was avoiding buying the right size cable in the first place?
you did, and I might be misreading your intent - but you seemed to suggest if concerned about the rating for the high draw equipment to double up the skinny cable - that implies a single length is insufficient.
let me ask the question a different way. If you have a doubled wire with crimped connectors what are the modes of failure? certainly not all will result in both wires being disconnected simultaneously.

RIBs get abused. They live in a highly corrosive environment. They get bounced around. The often get stored in damp conditions. The wiring is frequently not well mechanically installed. "Service" frequently involves the engine and trailer and ignores the electronics. The wiring is often hard to see/inspect. The fact you have rewired most of your ribs supports the case that eventually most "at some point" failure is likely. Am I going to far saying "almost inevitable"? Perhaps. Or perhaps you've been lucky so far. Either way its certainly not a negligible risk that a failure happens - as many people on this forum will be able to attest to.

No, engineered in most cases to spread the load evenly across 2 contacts where the current is deemed to be to much for a single contact.

Provided each single wire is capable of handling the current there is no problem with doubling up. the minimum awg I quoted was 20 which is rated at 8 amps at 12 volts DC over a maximum length of 15 ft. Sufficient for most circuits on the average 5M RIB.

I have rewired most of my RIBs because I have not been happy with the standard or design. Furthermore, as all RIB owners should do I regularly inspect the wiring for signs of chaffing or corrosion. Luck doesn't come into it, the lack of failure in my case may be have something to do with the fact that I am a qualified avionics engineer with 30+ year experience.

[Poly]

Originally Posted by Firefly

No, engineered in most cases to spread the load evenly across 2 contacts where the current is deemed to be to much for a single contact.

Provided each single wire is capable of handling the current there is no problem with doubling up. the minimum awg I quoted was 20 which is rated at 8 amps at 12 volts DC over a maximum length of 15 ft. Sufficient for most circuits on the average 5M RIB.

I have rewired most of my RIBs because I have not been happy with the standard or design. Furthermore, as all RIB owners should do I regularly inspect the wiring for signs of chaffing or corrosion. Luck doesn't come into it, the lack of failure in my case may be have something to do with the fact that I am a qualified avionics engineer with 30+ year experience.

"double wiring" into two different contacts is somewhat different to what you described as well. Personally I've always found putting two wires into one crimp connector to be less robust but that may be my error, although I suspect other non-experts may suffer similar issues.

If awg20 is fine for 15' at 8A/12V then why bother suggesting doubling up?

[Xk59D]

stop faffing about...get it bought.

[Seaflyer02]

Originally Posted by Xk59D

stop faffing about...get it bought.

Is it tinned?

[Stevem]

Many moons ago I was a Vehicle Mechanic in the Army and my mate was a Vehicle electrician. He was after some small gauge cable for Land Rover lighting etc.
One digit out on the demand form and about a week later his cable turned up, on the back of a low loader! Not quite a big a drum as above but not too far off. He still gets grief about it even though it was over 20years ago.
But yeah stop faffing and get it bought. :-)

[spartacus]

Echo what others have said about tinned cable. You only want to do this job once!

Add in Blue Sea battery isolator, fuse box and Carling switches

[GuyC]

Originally Posted by Richardnhunt

Hi all

After some advice. I am looking to do a rewire on a 5m RIB. I need to wire in the normal run of items - lights, plotter etc. My question is on wiring size. I have a grip (ish) on the normal formulas for wiring size, but given that I need to buy a reel of wire to run the wiring in a small rib, I am looking for some advice on:

a) a good general size of wire to use
b) suppliers
c) terminals

cheers

Rich

a) I'd say 1.5mm^2 would be more than sufficient for most things on the boat - lights, nav equipment, bilge pump. This doesn't include engine / charging related items and if you are running cable as a feed to a fuse box, then you will need to do it on a case by case basis but I doubt you would need anything bigger than 6mm^2 (which is the biggest cable you will fit in a yellow terminal)

b) Vehicle Wiring Products

c) Heat shrink pre-insulated terminals

I quite like Blue Sea Systems for fuse boxes and sockets e.g. USB charging socket which I suspect is probably a must on most boats nowadays.

I'd recommend making a wiring diagram not only to work out the design but so that you can refer to it in a few weeks / months to see what you did. Take a load of photo's of what you are doing.

Buy a decent set of crimpers, designed for whatever connectors you use and make sure you use the right size connectors for the wire. The red ones will do up to 1.5mm^2 and the blue ones will go from 1.5mm^2 to 2.5mm^2.

[Pikey Dave]

Originally Posted by GuyC

a) I'd say 1.5mm^2 would be more than sufficient for most things on the boat - lights, nav equipment, bilge pump. This doesn't include engine / charging related items and if you are running cable as a feed to a fuse box, then you will need to do it on a case by case basis but I doubt you would need anything bigger than 6mm^2 (which is the biggest cable you will fit in a yellow terminal)



b) Vehicle Wiring Products



c) Heat shrink pre-insulated terminals



I quite like Blue Sea Systems for fuse boxes and sockets e.g. USB charging socket which I suspect is probably a must on most boats nowadays.



I'd recommend making a wiring diagram not only to work out the design but so that you can refer to it in a few weeks / months to see what you did. Take a load of photo's of what you are doing.



Buy a decent set of crimpers, designed for whatever connectors you use and make sure you use the right size connectors for the wire. The red ones will do up to 1.5mm^2 and the blue ones will go from 1.5mm^2 to 2.5mm^2.

+1[emoji106] I found that my "pro" ratchet crimping pliers damaged the insulation on the heat shrink crimps, so I had to resort to the el cheapo type without the ratchet action. A hot air gun is a godsend. I bought an adhesive lined heatshrink selection box from Kojaycat.

[Bigtalljv]

And if you are going with separate switches and circuit protection I love these, https://www.bluesea.com/products/cat...Breaker_Blocks

Breaker blocks instead of fuses.