wiring looms

[WotEver]

On a 12V (and dare I say it, 24V too) system I bet 8.999 times out of 10 the voltage drop determines the cable thickness...

The very same point that I made in my original reply (although you explained it in greater depth).

 

Tony

[Murflynn]

It was actually 11MV

 

 

I doubt it. 11KV is a standard for distribution, never come across 11MV.

 

400KV is the highest used for transmission lines in the UK, and would be buried in a special corridor.

Edited October 4, 2016 by Murflynn

[WotEver]

I doubt it. 11KV is a standard for distribution, never come across 11MV.

 

400KV is the highest used for transmission lines in the UK, and would be buried in a special corridor.

I doubt it too - I was quoting what had been written - 11,000kV.

[jddevel]

Just to expand on the points I made firstly the various comments discussed by those obviously technically better informed regarding boat wiring goes some way to why my ignorance regarding electrical wiring is why I`ve decided to use LoomTec. My basic knowledge I fear may lead me to make both errors and assumptions as a human I may certainly regret. Their guarantees and suggested experience go some way to hopefully avoiding this.

Regarding the comments about the underground cabling. Firstly the ducting I had to remove was servicing one domestic three bedroom home and was as supplied by Western Distribution for me to lay in the trench also accommodating the gas and water main. All at the regulation depths and in the order for those utilities. Regarding the title I used for the 11000kva cable this may well be not its correct title -please excuse my ignorance-see remarks I`ve made above. It was a cable laid in along with other services to supply an industrial estate in the event that work required the normal supply route was shut down. It was buried at over two and a half metres down and 10 metres from its supposed position. Yes the area was swept with a CAT but for some reason on commencement of work showed nothing to concern me. At two and a half metres and with no warning tape it was far deeper than I believe it should have been buried. But I stand corrected.

[Theo]

Dear all

 

There have been a couple of requests in the body of this topic to move and close this topic. Having read some of if it seems to me that it is appropriate for BB&M. It is about on of the processes involved in building a boat. I think that the content is interesting and many members will find the discussion educational.

 

I would propose to leave it as it is and let the discussion continue.

 

I hope that this is OK with everyone.

 

Theo

[WotEver]

Just to expand on the points I made firstly the various comments discussed by those obviously technically better informed regarding boat wiring goes some way to why my ignorance regarding electrical wiring is why I`ve decided to use LoomTec. My basic knowledge I fear may lead me to make both errors and assumptions as a human I may certainly regret.

I don't believe that anyone was suggesting that if you don't have or wish to acquire the knowledge to wire your boat yourself that you shouldn't use a professional. Our surprise was that you were going to have it wired by means of a supplied loom. Personally I believe that this approach will result in difficulty and compromises when you come to fit out the boat - what happens when you change your mind about the location of the water pump, or decide that the light fittings don't really work where you thought they would? How will the cables be terminated to suit the equipment on board?

 

There are plenty of boat electricians about who could advise on cable sizes, run the cables, terminate them etc, an approach which many self-builders take and which I am sure would be more cost-effective than having a loom created.

 

However I wish you luck with your venture.

 

Tony

[Murflynn]

quote from Loom Tech website:

To build a safe system, and to comply with the various regulations on voltage drop, all the conductor runs in a boats electrical system have to be measured and a voltage drop calculation carried out prior to installation to ensure that the correct size cable is fitted ( a painfully slow process if you are installing your conductors one at a time, and as such prone to mistakes being made or potentially dangerous shortcuts being taken )

 

I do not recognise the potentially dangerous situation that appears to be the result of an over-imaginative and alarmist viewpoint held by the proprietor of the company.

 

Of course you don't have to measure the length and do painfully slow voltage drop calculations for each and every cable run. For example - you do it once, for the longest lighting run, choose an appropriate size cable, then use the same for all lighting runs.

 

I can't see why measuring and doing calculations is related to installing cables one at a time.

 

 

................. on the other hand, if I was building and selling a series of complete boats of identical layout then I might consider having ready-made looms. But how many boats are not customised to some extent?

[Alan de Enfield]

Indeed it is. It's also usually coaxial if it isn't SWA.

 

I think you may mean "concentric", or "split concentric"

Co-Axial is the stuff used for aerial leads, has a single 'core' (conductor) and has either a foil tape, or a copper braid as an electrical 'screen'.

[Alan de Enfield]

 

 

................. on the other hand, if I was building and selling a series of complete boats of identical layout then I might consider having ready-made looms. But how many boats are not customised to some extent?

 

In the automotive industry, to get the economies of scale and minimise stockholding of numerous variants, harnesses tend to be built for the 'highest level' car, this means that on a 'base level' car there will be the odd connector or two, not attached to anything, & - yes - it uses more wires and connectors but is far cheaper to produce than having to chop and change the harness build boards every few hours.

[Tony Brooks]

quote from Loom Tech website:

To build a safe system, and to comply with the various regulations on voltage drop, all the conductor runs in a boats electrical system have to be measured and a voltage drop calculation carried out prior to installation to ensure that the correct size cable is fitted ( a painfully slow process if you are installing your conductors one at a time, and as such prone to mistakes being made or potentially dangerous shortcuts being taken )

 

I do not recognise the potentially dangerous situation that appears to be the result of an over-imaginative and alarmist viewpoint held by the proprietor of the company.

 

Of course you don't have to measure the length and do painfully slow voltage drop calculations for each and every cable run. For example - you do it once, for the longest lighting run, choose an appropriate size cable, then use the same for all lighting runs.

 

I can't see why measuring and doing calculations is related to installing cables one at a time.

 

 

................. on the other hand, if I was building and selling a series of complete boats of identical layout then I might consider having ready-made looms. But how many boats are not customised to some extent?

 

Absolutely.

 

And I have a question about a "faulty" 12V fridge and freezer that makes the volt drop calculation for each cable claim suspect. However I have tried to warn the OP, I just hope he takes my advice.

[WotEver]

 

I think you may mean "concentric", or "split concentric".

I did indeed.

[WotEver]

 

In the automotive industry, to get the economies of scale and minimise stockholding of numerous variants, harnesses tend to be built for the 'highest level' car, this means that on a 'base level' car there will be the odd connector or two, not attached to anything, & - yes - it uses more wires and connectors but is far cheaper to produce than having to chop and change the harness build boards every few hours.

I'm a member of several Jaguar forums and Facebook groups and a very common question is "What's this plug in the boot for?" The answer is always an option that wasn't fitted.

[Arthur Brown]

You can only make a loom correctly when you know every cable, and every appliance to be fitted, it's current consumption and duty cycle and it's exact place and exact cable route.. A loom precludes any subsequent refitting or added items. Looms are used after lots of design work for large production runs -like cars. where 100hours of design (CAD) time is justified over 100K production models.

 

IMO a loom is of negative value because the layout of the boat may change in it's lifetime and electrical items may well get swapped out over the years.

 

If you can, please install two trunking systems one for 12/24v and one for mains(any 230v inc inverter). When you think you have finished putting all the wires in each then run a loop of string down each so that you can pull more cores in as wanted without losing the string for the next job.

 

Cable ratings depend on the thermal properties of the system (Trunks or looms hold heat) and on the volts dropped along the cable by peak and steady running currents.

 

If you think that Devon and Cornwall can't offer boaty services think what all the fishing boats do for repairs.

[Tony Brooks]

If you think that Devon and Cornwall can't offer boaty services think what all the fishing boats do for repairs.

 

There may be a slight trip up in that.

 

A while ago I had a question from a West Country fisherman who was having constant failure problems on with a 24 volt cable breaking. It turned out that he was rewiring using ordinary automotive cables rather than ones with tinned strands so corrosion was very rapid.

 

We (inland fresh water boats) can get away with ordinary copper strand cables but seagoing craft should not so by using local expertise he may end up spending very slightly more on the cables but at least they will be very much more corrosion resistant in the very long term.

[Alan de Enfield]

I'm a member of several Jaguar forums and Facebook groups and a very common question is "What's this plug in the boot for?" The answer is always an option that wasn't fitted.

 

Although not relevant for Canal boats in the UK -

When I was working with an automotive harness maker in South Africa, they had a huge problem that the harness fixings did not 'line-up' with the holes in the car. It was found that a harness manufactured during the 'heat' of the day, could be over 12" longer than one manufactured in the early morning, or it 'shrunk' when installed into a car in an air-con factory. We had to develop a 'movable' fixing that once taped on could be slid to meet up with the hole.

[WotEver]

 

Although not relevant for Canal boats in the UK -

When I was working with an automotive harness maker in South Africa, they had a huge problem that the harness fixings did not 'line-up' with the holes in the car. It was found that a harness manufactured during the 'heat' of the day, could be over 12" longer than one manufactured in the early morning, or it 'shrunk' when installed into a car in an air-con factory. We had to develop a 'movable' fixing that once taped on could be slid to meet up with the hole.

Yes I know we're OT here but I find the above fascinating. That would never have occurred to me.

 

Tony

... by using local expertise he may end up spending very slightly more on the cables but at least they will be very much more corrosion resistant in the very long term.

I suspect that it would still be cheaper than a loom.

[Reddwarf]

getting back to what the original post was about i don't actually think this is a bad idea. I think there are possible pitfalls to doing this as others have said and clearly this needs to be considered. There are a couple on youtube that are fitting out there own boat and electrical wiring caused a massive amount of grief as they were fitting the wiring with no experience at all and no real DIY skills certainly not electrical. I think getting them in to design the loom for you would need to be done when you're confident of all the electrical point and position of everything and installed at the right stage of the build. I think this is a better method of lets read things then have guess what is right method the couple used on youtube

 

i would go for someone that is experienced in boat wiring as the first choice but as often is the case with sailaways people do it to save money so a pre manufactured wiring loom fits between DIY with no real clue and getting a qualified boat electrician in. Building a wiring loom should be a relatively quick process so should be a lot cheaper than someone to wire the boat from scratch. The boat owner is then picking up the time to fit in place and do all the final terminations.

 

It's a different approach i see no reason to knock it. so long as the boat owner is confident with the company and aware of what they are picking up on the final fixing in place it's a massive improvement over the diy approach a lot of people have done in the past

 

it would be good to see photos and report back how it went the good and bad,hopefully all good.

[WotEver]

Building a wiring loom should be a relatively quick process so should be a lot cheaper than someone to wire the boat from scratch.

I don't follow this logic at all. Every boat is unique, therefore the loom will be bespoke. I am confident that it will be a substantially more expensive route than having a boat electrician specify and run the cables.

[Reddwarf]

I don't follow this logic at all. Every boat is unique, therefore the loom will be bespoke. I am confident that it will be a substantially more expensive route than having a boat electrician specify and run the cables.

If it's more expensive than getting a boat electrician then you are correct. but making a loom should be a quick process compared to installing all the wiring (1st fix and doing all the termination (2nd fix). The cost saving would be in the boat owner installing the made up loom and doing all the termination himself this is were the cost saving is.

 

As said in a previous post car manufacturers make up looms that drop into a car they don't have an auto electrician sat in the car running individuals wire to each component it would take days to do one car. All the loom manufacture is doing (I assume) is to run the lengths of cable as per site visit fit it in flexible conduit label what all the end of the wires are for and where on the boat (cable length should give this away) all you would have is bare end of cables have a look on their website effectively they are doing the first fix runs. Not sure if a boat electrician would be happy just doing the first fix and walking away for the boat owner to complete.

 

Like anything you have to weigh up the cost and possible pitfalls. but as i said above the couple on youtube did all their own electrics i think this is an alternative to get a boat electrician in and someone doing DIY.

 

Edited October 5, 2016 by Reddwarf

[WotEver]

I assume that the 'couple on YouTube' referred to is ZeroGravity and if so I agree, they're pretty clueless.

 

They commented that there were voltage drop tables but they "only went up to 10 or 15 metres". Well guess what, 20 metres is double 10 metres...

Edited October 5, 2016 by WotEver

[WotEver]

Any boat electrician would be happy to do as much or as little as required. Not only would he be happy for you to run much of the cable yourself but he'd most likely welcome it.

 

You keep referring to cars - it's been explained several times now that when you're building a few hundred thousand of the same car it makes economic sense to have looms pre-made. A one-off narrowboat is a completely different proposition.

 

One of the ways where a DIY fitout often fails is on poor terminations and the loom certainly doesn't appear to address that.

[Reddwarf]

No comment on that one i was looking at doing a sailaway i would consider myself reasonable confident with electrics but could see doing the research and calculations would be very time consuming as well as running all the cables. someone having done all the calculation and all you need to do is secure the loom in place and then complete the final termination would appeal to me or at least enough to look into.

[WotEver]

The calculations are not time-consuming nor onerous. In fact they're very simple.

[Reddwarf]

Not disagreeing with you at all. I see it as an alternative worth considering the original poster might come back with some figures.

 

If you can find an electrician is happy for an amateur to do part of the install or final termination then great. certainly when it comes to house electrics no electrician would do this unless as a minimum they could inspect and test the final installation

[Arthur Brown]

To make a loom someone has to know what cable to put in what places and what lengths and connectors will be needed. If you are making a lot of looms than you assemble a frame with pegs in all the right places and reels of the right wire already in place, then cable gets pulled round the pegs and terminated. For ONE loom this whole process is a waste of time and space, pull the right cable in the finished place and terminate as needed.

 

There are plenty of Youtube vids on how to make a cable loom. You need to plan how to get the loom through all the tight spaces that there are on a boat.

 

You cannot loom mains cables with battery cables.