electric wiring ducting

[Owengriffiths]

Hi, am in process of battoning out the boat prior to spray foaming insulation. There are metal conduits down the side of the boat but I intend putting in wire ducting wherever I need wiring before the spraying. This is mainly the ends of the boat and down the middle.

 

I have two thoughts- put it in now...but is it better to use metal or pvc ducting, both seem available????

 

Or alternatively I tack wood where i want the wiring and then remove later leaving a clean area for wire ducting to be inserted later.??

 

I found the cable calculator thing very useful, will go and get the dual core wire and the ducting tomorrow,

 

And i should add do i want LSF coated or PVC sheathed or does it make no difference???

 

A

Edited September 25, 2014 by Owengriffiths

[Chalky]

I used standard 25mm cable conduit (tube type) and back boxes before I fitted the polysytrene insulation. I used the standard clip together box type conduit under the gunwales for the main runs. Plastic has the advantage of being insulated and coming in different colours - I used black for 12V circuits and White for the mains ones. Has the advantage I can look at the conduit and know what's in there. I've found the conduit to be invaluable as its allowed me to update parts of the electrical system easily.

[Paul G2]

If by "dual core" you mean two wires that are enclosed together in an outer sheath, that type of wire is not meant to be used inside conduit. The heat doesn't dissipate properly. You should use single wires inside conduit - you can put a bunch of singles inside the conduit, you just don't want to use the wires that are inside a sheath. There are specs for how many wires in each conduit that should be readily available with a search.

 

PVC conduit would probably be easier for an amateur. You can buy the ends and offsets instead of having to bend them yourself. Even with PVC though, make sure to clean the ends after making a cut with a piece of emery cloth. You don't want to tear the insulation on your wire as you pull it through. Try to plan ahead and pull your wires all at one time. Pushing and pulling a snake through conduit that has wires in it can damage the wires that are in there.

 

Make sure your boxes and conduit are attached firmly. Pulling the wire through them can pull them right off the bulkhead if they aren't. Pulling wire is a two person job and you need someone who is not a total idiot feeding the wires into the conduit. Actually, hiring an electrician to do your wiring is money well spent. It's not as simple as it might appear.

 

Whatever you decide, good luck with you project!

[pippawatson]

Does this help?

http://walkerstug.blogspot.co.uk/2012_05_01_archive.html

[John V]

remember not to mix 240v wiring and 12v or 24v in the same enclosure. The square or rectangular clip together box is called trunking not conduit.

 

if you are pulling lots of cable it's worth investing in some "pulling compound" from an electrical wholesaler. and either put a "pull cord" in place as you assemble the conduit (it's worth glueing the joints if they are going to be inaccessible when pulling)) or invest in a cheap electricians "mouse"

[b0atman]

A wise move is when starting from new is to put in next size up wire this gives less volt drop and potential for future additions .

[phill]

Have you seen the price of copper? !!

[ditchcrawler]

Have you seen the price of copper? !!

Go 24 volt then

[Chalky]

Have you seen the price of copper? !!

 

Or use aluminium wire.

[phill]

The savings and availability of 24V stuff - no longer at a premium - mean it's a smart move.

 

Solar controllers half the price too.

 

Or use aluminium wire.

 

Is that viable?

[John V]

 

Is that viable?

 

theoretically yes practically no physically bigger for the same carrying capacity and very stiff

[Paul G2]

 

theoretically yes practically no physically bigger for the same carrying capacity and very stiff

 

And don't forget de-ox on every connection. That'd be real fun doing finish.

[Ray T]

 

Or use aluminium wire.

 

When the price of copper last rose sharply, in the 70 / 80's I think, BT decided it would be cheaper to use aluminum cables in the external network. In a period of about 15 years the ally conductors became brittle and prone to breaking at the slightest touch.

 

The idea was abandoned and vast sums were then expended replacing these cables with copper.

 

I would be wary of using ally cables in a narrow boat partly due to the vibrations it experiences leading to fatigue of ally cables.

[DHutch]

Yep, now a few people who have houses with aluminium wiring, not good. Although its common for large transmission lines.

[Ray T]

Yep, now a few people who have houses with aluminium wiring, not good. Although its common for large transmission lines.

 

Daniel, BT uses Ally for its bus bars in telephone exchanges to carry the high current needed to the equipment.These bars are about 1/2" thick by 12" wide and there can be as many as 4 running in parallel. They are very rigid and not prone to moving so they don't suffer the same stresses as smaller cables.

 

If any metal tools are accidentally dropped on them and cause a short there is one almighty bang, the tool vaporizes, alarms go off all over the place and many searching questions get asked.

[john_r]

I would be concerned that pvc conduit in contact with polystyrene might react. Might be worth checking if the exact kind of plastic would do so.

 

 

ETA this is in response to Chalky's comment, I did see the OP will not be using polystyrene.

Edited September 26, 2014 by john_r

[John V]

I would be concerned that pvc conduit in contact with polystyrene might react. Might be worth checking if the exact kind of plastic would do so.

 

 

ETA this is in response to Chalky's comment, I did see the OP will not be using polystyrene.

 

AFAIK It's the plastcisers in cable that make it flexible, these migrate into the polystyrene and the cables insulation becomes extremely fragile

 

rigid or semi rigid conduit is manufactured differently, the quantity and type of plasticisers is not the same and although eventually it becomes more brittle (it does when exposed to sunlight as well) it does not disintegrate in the same way

[Owengriffiths]

Have spent the day cutting up 2 by 1 wood and glueing and drilling it in place. I can't get the damn sticky black glue off my hands/ clothes/ face / children .

 

 

Have now spent the evening reading the build blog provided by pippa. Omg I am not worthy and can only dream of such build quality and beauty, but yes it was helpful thanks.

[Alan Saunders]

I am contemplating the same problem of cable sizing or oversizing. Versus the cost of copper it is usually more economical to buy longer/multiple reels of the largest diameter cable that you require rather than try to economise with minimum sized cables. Of course, the conduit, trunking etc. will have to accomodate the multiple, larger diameter cables.

 

Oversizing, minimising voltage drop, will serve you well if when your battery is low or you decide to spur off additional circuits in the future. Many posts here suggest that some appliances especially DC compressor refrigerators need a dedicated circuit with much larger conductors than the general wiring for lighting, pumps, TV etc.

 

HTH, Alan

[smileypete]

If sprayfoaming after ducting, best make sure there's not just an air gap to hull behind, or it might attract condensation.

 

For larger cable in larger, medium and smaller sizes; welding cable, trirated cable, and equipment wire respectively can be economical ways to buy. Proper equipment wire has tinned copper strands which is an bonus.

 

In a bigger boat and a DIY fitout, having several localised fuse boards for DC fed from a radial of thick cable might help to standardise on a smaller range of cable sizes and so save money. Probably also makes future mods easier, so less need for ducting?

 

cheers, Pete.

~smpt~

Edited September 27, 2014 by smileypete

[rupertbear]

In a bigger boat and a DIY fitout, having several localised fuse boards for DC fed from a radial of thick cable might help to standardise on a smaller range of cable sizes and so save money. Probably also makes future mods easier, so less need for ducting?

 

 

I am considering using this option, using 35mm² welding cable. I am concerned, though, by the number of connections.

 

At each point where I wish to take off a spur there would be two cable/crimp tag connections and two crimp tag/stud connections introduced into the run. I have an hydraulic crimper for applying the tags.

 

Am I worrying unnecessarily?

[Paul G2]

 

I am considering using this option, using 35mm² welding cable. I am concerned, though, by the number of connections.

 

At each point where I wish to take off a spur there would be two cable/crimp tag connections and two crimp tag/stud connections introduced into the run. I have an hydraulic crimper for applying the tags.

 

Am I worrying unnecessarily?

 

If you use good quality connectors and good quality bus bars, the electricity passing through the connections shouldn't be a problem. Your major concern will be vibration wanting to work the connections loose. You'd probably want to use lugs with sufficient length for double bolts to firmly lock the connections and keep them tight.

[smileypete]

 

I am considering using this option, using 35mm² welding cable. I am concerned, though, by the number of connections.

 

At each point where I wish to take off a spur there would be two cable/crimp tag connections and two crimp tag/stud connections introduced into the run. I have an hydraulic crimper for applying the tags.

 

Am I worrying unnecessarily?

 

A bit maybe, could try some sample crimps and try levering them apart.

 

Sometimes a smaller die is needed to get a good crimp on certain tools and terminals, these topics could be worth a read:

 

http://www.canalworld.net/forums/index.php?showtopic=60258

http://www.canalworld.net/forums/index.php?showtopic=69365

 

I'd prefer spending a bit of time and trouble making sure connections are 100%, the skills and knowledge can then pay back many times over.

 

cheers, Pete.

~smpt~

Edited September 29, 2014 by smileypete

[BlueStringPudding]

Hi, am in process of battoning out the boat prior to spray foaming insulation. There are metal conduits down the side of the boat but I intend putting in wire ducting wherever I need wiring before the spraying. This is mainly the ends of the boat and down the middle.

 

I have two thoughts- put it in now...but is it better to use metal or pvc ducting , both seem available????

 

Or alternatively I tack wood where i want the wiring and then remove later leaving a clean area for wire ducting to be inserted later.??

 

I found the cable calculator thing very useful, will go and get the dual core wire and the ducting tomorrow,

 

And i should add do i want LSF coated or PVC sheathed or does it make no difference???

 

A

I'm giving away 15 or more metres of conduit/ducting. See the "BSP Free Shop" thread if you or anyone else wants it. Otherwise it's going in the bin as soon as I can get it down to the tip.

[rupertbear]

 

A bit maybe, could try some sample crimps and try levering them apart.

 

Sometimes a smaller die is needed to get a good crimp on certain tools and terminals, these topics could be worth a read:

 

http://www.canalworld.net/forums/index.php?showtopic=60258

http://www.canalworld.net/forums/index.php?showtopic=69365

 

I'd prefer spending a bit of time and trouble making sure connections are 100%, the skills and knowledge can then pay back many times over.

 

cheers, Pete.

~smpt~

 

Thanks for the links. I have used the cable/tags/tool previously for battery and starter circuits, the info in the links confirms my previous experience and conclusions.

 

It would be good for peace of mind to be able to test each joint but the resistances involved would (hopefully) be too small for everyday meters.