Using a large power line

[troubleScottie]

Assuming that your battery is in the front and you want power to the rear/galley, has anyone run a single large wire (6awg or less) to a fusebox in the rear rather than separate smaller wires to each appliance.

The thought is less power loss and flexibility to add more components later.

Pluses, minus, throughts?


Assuming you want to add more electrical later, has anyone added empty wire chases? Awhile ago, I saw several TD with electrical conduit in the floor. This allowed for wiring from the front to the rear without going through the walls or roof and keep the wiring unexposed. This type of construction does not appear to be very common more recently.

Thoughts?

[bdosborn]

Linky
People do it all the time, get a fuse block and you're good to go.

Bruce

[Squigie]

Use a fuse or breaker in the main line, near the battery, to protect against shorts in the run to the rear.

[bdosborn]

I like these, they put the fuse right at the battery:

https://www.amazon.com/gp/product/B07LC6273Z/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

The fuses are a little spendy so it gets expensive if you start blowing them with sloppy wrench work.

Bruce

[tony.latham]

...a single large wire (6awg or less) to...

With this last build, my battery is in the galley and my fuse box is behind the headboard. I just didn't have the room I needed at the battery for the fuse box.

So yeah, doing this is electrically is okay, but I don't think you need anywhere near 6 AWG. (25-30 amps?) I ran a fused 12 AWG from my battery to the fuse box. I can't imagine we'll ever pull 15 amps through it. I've got that cable running under the chassis so it is replaceable.



Tony

[featherliteCT1]

The Renogy wire size calculator says that 6 AWG will carry 14 amps at 12v a distance of 10 feet with 1% voltage drop.

15 amps that same distance requires 4 AWG.

https://www.renogy.com/calculators#tab_solar-cable

My theory is that volts and amps are precious and hard to come by, so I always size for a 1% drop in voltage.

[bdosborn]

3% is usually used as a target for voltage drop, representing a good balance of performance versus cost. But, if you've got the cash it doesn't hurt to go lower. I sized all my wires at 3% except for one, the battery charging wires. I was using a #6 marine wire to carry 45 amps (sized at 3% VD) and it got warmer than I liked so I bumped it up to a #4.

Bruce

[tony.latham]

3% is usually used as a target for voltage drop, representing a good balance of performance versus cost. But, if you've got the cash it doesn't hurt to go lower. I sized all my wires at 3% except for one, the battery charging wires. I was using a #6 marine wire to carry 45 amps (sized at 3% VD) and it got warmer than I liked so I bumped it up to a #4.

Bruce

Dang!

T


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[troubleScottie]

Thanks for the input.

More on the design. The front will have the battery, chargers, and several circuits eg fan, lights, heater. The rear will have more equipment : pump, water heater, frig, radio, etc.

I am also thinking I want to be able to selectively power things. (yes overdesigned/over engineered). So, a big wire to a fuse block. Then to each appliance to an individual ground back to a switch back to the battery.

To remove the switch-ability of each appliance, one could use a single ground back to the battery with each appliance attached to a common bus.

[GTS225]

So, a big wire to a fuse block. Then to each appliance to an individual ground back to a switch back to the battery.
To remove the switch-ability of each appliance, one could use a single ground back to the battery with each appliance attached to a common bus.

Wait......the way I read this, you plan on fusing the power fed to individual appliances, and switch the ground for them individually. That is not standard practice for non-computerized, 12vdc electrical systems. Standard practice has always been power(+), fuse, switch, load, and back to power(-) through a ground. It can be a common ground, sized for the expected current, or individual wires to a common bus.
The advent of switching grounds for control purposes was brought about by automotive computer systems not liking to switch the "hot" wire, and having bad reactions to the current rushes. Seems they like grounding, and get plenty of it, in addition to switching the ground for control.
Your plan will work, it's just not common/standard practice.

Roger