Re-wiring madness...

[James W]

I've just finished an electrical refit on a 90 footer, 240ac, 12vdc & 12vdc, new everything including circuit breaker panels, consumer units, bus bars, sub panels, the lot, the largest one I've ever done and to be honest it's been a bit of a challenge (160m of AC cable alone), for what it's worth I'd use tinned single core except for long runs where the feed panel and return bus are close like mast nav lights and the like, single cable (ultra low voltage at any rate) is better than twin if not bundled too tightly as it has lower losses than tightly bundled stuff. Tinned copper un insulated terminals with separate covers are a good way to go as they make a good "ass cheek" roll over form which is very strong, avoid those red, blue, yellow auto crimps like the plague. I rarely do a schematic but always do a routing description, I identify the cables with printed heat shrink tube describing the function rather than using numbers and a separate chart now. try where possible to plan the job well before even starting, heavier single cable runs to smaller sub panels where possible saves time and is often easier for routing, work out the total load on the panel for the feed cable, not just for now but possible future additions where appropriate. Whether or not to start from scratch is a decision only you can make based on what you can see before you, but a blank canvas will give you a result you know will last if you are unsure about the state of the current install. Use the best quality consumables and crimping tool(s) you can afford. There is some good quality British made thin wall tinned cable around that is fairly reasonable if bought in bulk, you can always use it all with a bit of overkill on some circuits. A simpler and more accurate way to work out cable sizes which avoids the confusion of whether the table being used is based on round trip or simple distance from battery is 10.75 which is the constant assuming copper, times load amps, times round trip in feet, divide by the required volt drop (in volts) this gives the circular mil area which is easily convertible to AWG or mm2.

Thanks David, that's definitely helped a lot. I haven't decided quite what to do yet but you've certainly set me on the right path.

Much appreciated!

 

[Robert Wilson]

Fascinating and very informative thread/Post. Thank you one-and-all.
You guys have well and truly convinced me that my intentions to DIY re-wire my 30footer is shere madness
Looks like the boatyard will be getting another contribution to their civil-service sized Pension Scheme

 

[James W]

Fascinating and very informative thread/Post. Thank you one-and-all.
You guys have well and truly convinced me that my intentions to DIY re-wire my 30footer is shere madness
Looks like the boatyard will be getting another contribution to their civil-service sized Pension Scheme

Go for it.....we can mess it up together!

 

[oldsaltoz]

I assume that you mean this sort of stuff:

http://www.amazon.co.uk/Outside-Diameter-Binding-Natural-Colour/dp/B0034R3NNM/ref=pd_sim_sbs_ce_5

It immediately came to mind to suggest this style of cable tidy when the OP said the multiple single core wires looked a mess on the starboard side.

Pretty close to the stuff I use but mine is a bit tighter and looks more like a flexible conduit with little or no gaps and is black. it also fits inside standard electrical conduit, making it easy to install through bulkheads and providing good support if needed.

Good luck and fair winds.

 

[Robert Wilson]

Go for it.....we can mess it up together!

MY mess will be bigger than YOURS

Good luck to you.

 

[oldsaltoz]

When I had some wiring done on Rogue in 2006, the electrician used a multi core cable with about 8 different coloured wires in one case. This enabled him to wire 7 different things with one cable, using a common negative. It was very neat, and seemed very sensible.

Clearly, the negative base to be thick enough to carry the max current that might be drawn, and appropriately fused.

Seems to cover a few bases?

I run separate earth returns for most devices, you only need a single earth fault to shut down 7 devices the way it's been wired.

Good luck and fair winds.

 

[David2452]

Interesting post, but how do you print onto heatshrink ?

Boo2

Kroy printer and heatshrink cartriges, only drawback is cost ( like an inkjet it's not the printer cost so much as the heatshrink cartriges and only 1.6m on each one) but I use it a lot and allow for it in consumables. Can offer pre printed if anybody wants some, I alo use the machine loads of identyfing jobs.

 

[James W]

MY mess will be bigger than YOURS

Good luck to you.

I'll let you know!

 

[alahol2]

If I may... I have toyed with the idea of trying to tidy/replace some of the wiring. One point I'm never too sure about. There are something like 15 cabin lights port, starboard and centreline in three cabins. What would be the best way to wire it? Ring main type of thing, wire to port/starboard/central, separate wires to a couple of busbars?

 

[oldsaltoz]

If I may... I have toyed with the idea of trying to tidy/replace some of the wiring. One point I'm never too sure about. There are something like 15 cabin lights port, starboard and centreline in three cabins. What would be the best way to wire it? Ring main type of thing, wire to port/starboard/central, separate wires to a couple of busbars?

My first priority would be to wire the lights on 3 circuits so that I has 'some' working lights in each area even 2 out of the 3 circuits failed.

Then I would note the power drawn by each light and ensure the load was spread across the 3 circuits.

Finally I would ensure each circuit had it's own earth return cable.

PS with that many lights I would be looking into LED's to reduce the total power consumption as well.

Good luck and fair winds.

 

[grumpy_o_g]

If you're going to re-wire and it's your own boat you may have two choices remember - big bang or one bite at a time. Often you can break up the job into quite small chunks. Before you actually start though I'd ask yourself what you can afford to have fail and what you can't. Obviously the stuff you can't afford to fail gets priority.

The other thing I do is start by creating a simple schematic as David says. This isn't just so that you know what wire goes where - it's also to make sure you understand how everything works, i.e do you really know exactly what each switch does and where it's fused, etc? Even things like how many bulbs you're switching on when you hit a cabin light switch may not be what you thought and when it gets to wiring the panel it can be a nightmare if you're not clear what's what.