AngusMcDoon
Well-Known Member
The whole of engineering is based on accepting historical advice. They are more commonly known as standards.
Bodging is less rigorous & more of a free for all.
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12v Cable frugality
- Thread starter Neeves
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Bodging is less rigorous & more of a free for all.
B27
Well-Known Member
Single core wire can work OK
It just needs not to get flexed.
It's good for things like wiring panels, where it can be bent to tight shpares and will stay in shpe. It then needs to be kept in shape, not allowed to flex.
It just needs not to get flexed.
It's good for things like wiring panels, where it can be bent to tight shpares and will stay in shpe. It then needs to be kept in shape, not allowed to flex.
ChromeDome
Well-Known Member
Just ignore members or replies you don't find helpful.
Refueler
Well-Known Member
Point taken !!
Trouble is - I cannot see why the joint fails ... and it does it at least once a year ... I have even applied stress relief silicon over them to help.
Neeves
Well-Known Member
You are quite right, I had made up my mind. What I was unaware of were the electrical implications of using single strand as opposed to multi - was there some quirk I had not heard of. If there is a quirk, other than the strands being brittle (and this is well known) - not a soul has mentioned it
As I said originally the cable is for a roving panel, its the panel that will rove, not the cable. The cable can effectively stay in situ - it could be 'almost' permanently secured - but I may change my mind. and find a better location.
If you look at the picture of our cat the obvious location of the 'roving panel' is on the foredeck (but put away when at sea - though even that might change). The panel will face the sun but that can be achieved with the cable simply exiting from a port light at the bow or from one of the 2 deck hatches and the cable run is a straight line.
My original idea was to simply bundle the insulated wires but this will be desperately clumsy. Now I think I'll strip the covers off and bundle the copper and then cover with heavy duty transparent shrink, 3:1 or 4:1, cover. I've used the cover on rope - and it distinctly lacks flex when shrunk
Jonathan
AngusMcDoon
Well-Known Member
For DC, no. Things get strange at RF.
fredrussell
Well-Known Member
Slight thread drift, but I’m intending to drill a 40mm hole in the bottom of my boat to create a nice water feature. I’m aware the naysayers will say my boat will sink, but they need to learn to be less negative.
Neeves
Well-Known Member
Nothing wrong with thread drift.
We have a couple of holes, actually (now that I think of them - lots) 2 of which I drilled in the bottom of our boat. But we don't need a water feature . I didn't ask for advice, I just did it. I used an appropriately sized hole saw. Our cat has not yet sunk.
Jonathan
Neeves
Well-Known Member
Currently I'm testing a folding solar panel and a monitor using a 10m solar lead. I want to use the 10m lead for something else but want to continue testing the panel. The panel is not critical, we have other panels and a wind gen. Longer term I'll make another decision.
I'm not monitoring daily, I'm too lazy, but checking every 2 -3 days.
Jonathan
Neeves
Well-Known Member
Historically Bridon made Dyneema ropes for yachts (they sold the business). We bought some 10mm to replace halyards and sheets. I spoke to them of our application (nothing special) and they told me that Rothmans had saved weight by stripping the covers off their reefing lines - but only the part of the line within the boom. This was because dyneema was not resistant to UV.
It took a long time before we all started to use uncovered Dyneema - which might be susceptible - but its insignificant.
Dyneema was always said to be resistant to abrasion - until it was shown otherwise.
Safety tether hooks meet specific standards, some have still been shown to fail.
Some of the testing I have completed has result in product being withdrawn - even though it met standard, set by the manufacturer.
Just because something is said repeatedly - does not mean it is correct. Applications change and might be modified to minimise characteristics.....
I'll resist mentioning anchoring.
Jonathan
Refueler
Well-Known Member
Historically Bridon made Dyneema ropes for yachts (they sold the business). We bought some 10mm to replace halyards and sheets. I spoke to them of our application (nothing special) and they told me that Rothmans had saved weight by stripping the covers off their reefing lines - but only the part of the line within the boom. This was because dyneema was not resistant to UV.
It took a long time before we all started to use uncovered Dyneema - which might be susceptible - but its insignificant.
Dyneema was always said to be resistant to abrasion - until it was shown otherwise.
Safety tether hooks meet specific standards, some have still been shown to fail.
Some of the testing I have completed has result in product being withdrawn - even though it met standard, set by the manufacturer.
Just because something is said repeatedly - does not mean it is correct. Applications change and might be modified to minimise characteristics.....
I'll resist mentioning anchoring.
Jonathan
I have a classic example of an item meeting a standard - became a common item in the industry - but had serious error that could be catastrophic.
I will not name the Brand as its an international name. But I am sure anyone with similar background to mine will recognise it immediately.
On tankers and various ships / terminals / sites - you can appreciate that flashlights need to be safe and secure.
A common brand of flashlight found on many tankers - in terminals etc. was approved by UL (USA) and also other agencies - it was economically priced and it became standard issue for many.
Its competitor had an extra feature - but that made its costs higher and it was therefore not as common to be found.
Imagine ...
In a world of flammable vapours, liquids etc' - the last thing you would want is for someone to be able to open a flashlight exposing the batterys inside. Not only that - but exposing the bulb as well. The brand had no Key lock to prevent its opening.,
The competitor had a specially designed key that only that key would work. It even went further - the instructions for the flashlight stated that having Key attached in any form to the flashlight was a breach of safety certificate.
rogerthebodger
Well-Known Member
EPIRB's are another safety item that has design issues in the design of the messaging to and from the satellite.
Having designed computer equipment with messaging to an forth it concerns me that there is not response message from the satellite back to the EPIRB confirming that the emergency message has been received and sent on to MRCC.
The same with the EPIRB test message as it does not confirm that the test has been sent and received thus proving end to end comms
Having designed computer equipment with messaging to an forth it concerns me that there is not response message from the satellite back to the EPIRB confirming that the emergency message has been received and sent on to MRCC.
The same with the EPIRB test message as it does not confirm that the test has been sent and received thus proving end to end comms
Neeves
Well-Known Member
Recall the new wonder drug for pregnant women in the 60s, Thalidomide.
We have another case now I Oz. it has suddenly been realised that cutting stone bench tops exposes operators to dust that may contain silica, almost definitely contains silica. Silicosis has been know of for decades - what were they thinking of.
Suddenly all operators either close or need wet cutting equipment. This should have happened as early as the 60s.
A well know marine company introduced a range of really good shackles - twice as good as anything else, but matched Crosby. Except they did not match Crosby. Testing clearly demonstrated they did not meet specification. When the mismatch was clearly demonstrated the supplier said the testing was wrong - and continued to sell same - some of you will have bought them. Sadly this is not a unique story - some of you may be using a snubber hook that is defective, a tether hook that is defective. You might know they are defective, if you read the right media - but you don't throw them out "she'll be all right mate'. How many of you are using tethers, harnesses, bosuns chairs outside their use by date.?
Returning to shackles - About 6 months later the specification was altered to match actual test results - no mention to customers that the ones they had bought were outside the new specification.
No-one questions
40, 50 years ago wiring of yachts was different to today. Practice today is better (and more complicated). DC single strand failure was well known, once wiring became more common place, and there was an easy alternative. Our wiring on Josepheline does not move, it is all bundled together and tightly cable tied. Some of the bundles contain the morse cables. There is no flex and no vibration. This introduces a new problem as it is impossible to remove a redundant wire and equally difficult to add a new wire.
I suspect single core wiring would be more than adequate (except it would not be tinned) and there is an alternative. Practices change
But hey ho - you all replace your tethers (don't you. ), and are happy to complain about my extension cable which is not a safety item.
Jonathan
We have another case now I Oz. it has suddenly been realised that cutting stone bench tops exposes operators to dust that may contain silica, almost definitely contains silica. Silicosis has been know of for decades - what were they thinking of.
Suddenly all operators either close or need wet cutting equipment. This should have happened as early as the 60s.
A well know marine company introduced a range of really good shackles - twice as good as anything else, but matched Crosby. Except they did not match Crosby. Testing clearly demonstrated they did not meet specification. When the mismatch was clearly demonstrated the supplier said the testing was wrong - and continued to sell same - some of you will have bought them. Sadly this is not a unique story - some of you may be using a snubber hook that is defective, a tether hook that is defective. You might know they are defective, if you read the right media - but you don't throw them out "she'll be all right mate'. How many of you are using tethers, harnesses, bosuns chairs outside their use by date.?
Returning to shackles - About 6 months later the specification was altered to match actual test results - no mention to customers that the ones they had bought were outside the new specification.
No-one questions
40, 50 years ago wiring of yachts was different to today. Practice today is better (and more complicated). DC single strand failure was well known, once wiring became more common place, and there was an easy alternative. Our wiring on Josepheline does not move, it is all bundled together and tightly cable tied. Some of the bundles contain the morse cables. There is no flex and no vibration. This introduces a new problem as it is impossible to remove a redundant wire and equally difficult to add a new wire.
I suspect single core wiring would be more than adequate (except it would not be tinned) and there is an alternative. Practices change
But hey ho - you all replace your tethers (don't you.
), and are happy to complain about my extension cable which is not a safety item.Jonathan
NormanS
Well-Known Member
What we're wondering is why you raised the subject in the first place, since you're so determined to do your own thing.Recall the new wonder drug for pregnant women in the 60s, Thalidomide.
We have another case now I Oz. it has suddenly been realised that cutting stone bench tops exposes operators to dust that may contain silica, almost definitely contains silica. Silicosis has been know of for decades - what were they thinking of.
Suddenly all operators either close or need wet cutting equipment. This should have happened as early as the 60s.
A well know marine company introduced a range of really good shackles - twice as good as anything else, but matched Crosby. Except they did not match Crosby. Testing clearly demonstrated they did not meet specification. When the mismatch was clearly demonstrated the supplier said the testing was wrong - and continued to sell same - some of you will have bought them. Sadly this is not a unique story - some of you may be using a snubber hook that is defective, a tether hook that is defective. You might know they are defective, if you read the right media - but you don't throw them out "she'll be all right mate'. How many of you are using tethers, harnesses, bosuns chairs outside their use by date.?
Returning to shackles - About 6 months later the specification was altered to match actual test results - no mention to customers that the ones they had bought were outside the new specification.
No-one questions
40, 50 years ago wiring of yachts was different to today. Practice today is better (and more complicated). DC single strand failure was well known, once wiring became more common place, and there was an easy alternative. Our wiring on Josepheline does not move, it is all bundled together and tightly cable tied. Some of the bundles contain the morse cables. There is no flex and no vibration. This introduces a new problem as it is impossible to remove a redundant wire and equally difficult to add a new wire.
I suspect single core wiring would be more than adequate (except it would not be tinned) and there is an alternative. Practices change
But hey ho - you all replace your tethers (don't you.
Jonathan
Refueler
Well-Known Member
Fair enough .... but led to interesting thread ... so why knock it ?
ylop
Well-Known Member
For some applications on a boat a single core cable is not as bad as the world would suggest. For a movable extension lead it’s probably the worst option. As the cable moves the copper work hardens and then suddenly snaps. If you have say 3 wires sharing the load, nothing fails at this point - all you have is two wires carrying load design for 3 and no indication of a problem. Sometime later the same will happen to one of the other wires. Now you have single conductor carrying all the current, presumably if it were rated for that you wouldn’t have installed multiple wires in the first place so not you have too much resistance generating heat and a fire risk. I guess you could fuse each core separately to protect it. The same sort of think can happen with multicofe except 1. It doesn’t work harden as easily because the way a big bundle of thin wires flexes; 2. If a single core snaps there are many other cores to share the load; 3. Even if multiple cores snap they are all in electrical contact with each other so share the load for most of the length stopping the overall resistance rocketing and generating loads of heat.
You say it’s not safety critical but I think it’s a fire hazard unless you put enough engineering effort in to mitigate that which will negate any financial saving.
Neeves
Well-Known Member
I was not determined to do my own thing.
The history of single core cable failing is well known. I do read and I do retain.
My application does not involve vibration nor flex. Vibration and flex, to me was irrelevant.
What I was concerned of was the use of multiple single core wires and whether there was some, lets call it 'electrical', reason that would be an issue. I freely admit to ignorance on matters electrical (though my ignorance may not be as minimalist as I suggest).
I did not know if there was something 'electrical' - but am aware there are markedly superior minds at play here and I thought I'd ask. If you don't know you actually don't know what to ask - if you knew what to ask you probably would not need to ask.
Now if you take the trouble to read all of the thread and filter out the calcophony of noise from the flock on flex and vibration you will find that some replies confirmed there was no 'electrical' issue and this was then reconfirmed recently.
What was disappointing that most members here are simply too young to have direct experience of single strand cable in yachts and none use of thick multi strand copper wire. You might be old enough - describe the wiring in a yacht before the dangers of single core wiring was defined and compare it with today's wiring looms.
But let us not despair many who posted took pleasure in being experts and really loved the baiting.
Jonathan
lustyd
Well-Known Member
If you put your engineering hat on for even a brief moment you'd realise that those cable ties have introduced fixed spots against which vibration will occur. Same reason soldering is frowned upon.
It doesn't take much of an experiment to see that solid core will work harden with vibration and movement, leading to a breakage. Just strip the insulation off of a solid and stranded core sample and wiggle them back and forth. Vibration is a micro version of this activity.
It doesn't take much of an experiment to satisfy yourself that a break in a cable introduces resistance which causes heat, and upping the Amps on that same experiment will quickly show the resulting fire.
It doesn't take long to ask your insurance company whether this documented evidence of you stating you'll ignore current advice will affect any future claims for fires on board your vessel.
Alex_Blackwood
Well-Known Member
All some of us are saying is that what you propose as an installation would be an anathema to any self respecting Electrical Engineer/ Technician/Electrician.
Your boat if you are happy with the bodge so be it. Would be interested to know how it all goes.
Neeves
Well-Known Member
I've put my engineers hat on and it raises some questions.
But first I fully accept your analysis.
Vibration and movement will lead to work hardening the individual wires might fail.
In isolation this is a risk - the question is how big a risk. I accept that it is inevitable - but to make a judgement I need to know how quickly, or slowly, this will happen.
I assume that historically this happened on yachts, an investigation was conducted resulting in the current recommendation to use multi strand copper wire, preferably tinned (but tinning is a red herring - ignore).
A question is how often did this occur what was the frequency, how long did this take to happen. If it takes 10 years, I'll have moved onto something else - anchors look interesting....
Considering the when - this would have been decades ago (so no marinas) yachts would have been kept on swing moorings or trots.
So did wires typically break within a week, a month, a year or was it more insidious 2-4 years. Was this common - were fleets of the then top of the range Moodys being re-wired...
We have two recent examples, Refueler and Roger the Bodger - use of strip on solar panels failing, How long did they take to fail?, one week, one month, one year a few years. Is this common - if so - solar panel makers have been ignoring reality.
I'm talking of making up a lead to test a solar panel over the next 3 months, if its interesting maybe 6 months. If the lead survives I may use it for 'something else'. There is no vibration, there is no flex. The cable is freely suspended. It is attached to an Anderson at the panel and then clipped to a secure bracket and is freely hung to be secured immovably, 10m away, at a locker lid and then attached to another Anderson. The locker houses a 200 amp hr battery, controller and meter (sadly not Victron). Meter displays, amps, voltage and total amps. I can introduce a load to the battery - any time I want.
Without the requested data - time, how long - then I need to test myself to know how long, hardening and failure, it takes to happen - in my specific environnment.
Jonathan
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