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  View original topic: Aux fuse box install tips
chuckpolzin Sun Aug 14, 2022 11:39 am

Hey guys planning on adding an aux fuse box like a blue sea systems or other similar unit.

Will be adding a “camping battery” with a bus depot battery isolater relay kit

Anyway. Had some questions on best location and install advice

I know they make models that either have a negative bus bar or without

I assume with the non bus model you would get all device grounds from the chassis?

Would you get the model with a negative bus for a cleaner install?
I assume i still wire the batt negative to a chassis ground either way?
Do you recommend under the front dash / kick panel area or somewhere in back?

Any advice on best way to wire up a second fuse box to an aux battery would be awesome. Thanks!!

dodger tom Sun Aug 14, 2022 12:06 pm

i’m a driveway mechanic, so forgive the possible stupid question….

why do you need a negative buss on a fuse box? don’t the two contacts just pass through one pole, usually positive?

if you mean a sub-panel (i.e., distributing aux power from a central location), then i understand.

chuckpolzin Sun Aug 14, 2022 12:09 pm

The box can sometimes have a negative / ground terminal block so the difference would be either you run a wire at each accessory to the chassis or body metal. Or run a negative wire back to the fuse block.

The two terminals on the standard fuse block are the hot leads its just the pre fuse “supply” and the post fuse “load”

bsairhead Sun Aug 14, 2022 12:10 pm

I would think the neg. bus bar would make for a less clean install. As the only reason to have a ground point is if you had a fiberglass body.

airschooled Sun Aug 14, 2022 1:24 pm

High end stereo installs can use a dedicated ground wire/circuit to eliminate hiss/buzz in quiet parts of songs.

Send me a PM if you want to chat aux wiring installs, I’ll be in Wisconsin at several of the CVVC and Milwaukee area club campout a this season.

Robbie

SGKent Sun Aug 14, 2022 2:15 pm

sometimes adding a dedicated ground buss on a DC system can cause a ground loop. I can't explain the dynamics. On a 120V AC system where different pieces of electronics are connected there can be differences in ground potential due to each piece of equipment having an isolated floating ground, but that is not typical in a 12V DC system. The best solution is following the manufacturer's suggestions as to how to mount and wire. I might add, using different 12V negative ground buss on DC equipment in a car can cause issues if those grounds find different voltage potentials. The car body is the ground plane and the 12V battery negative mounts to that. (Only older systems from the 50's and early 60's use a positive ground) If one is getting a hiss in the system during quiet moments in the songs, something else is going on. Nothing like a long piece of wire to act as an antenna is also a possibility when a small dielectric is created after the long ground connection ages and a small amount of corrosion sets in.

telford dorr Sun Aug 14, 2022 7:45 pm

Fuse boxes with a ground bus are for use on boats (which are generally made from non-conductive materials). Gives a convenient place to connect the ground wire from loads. Not needed on a bus.

SGKent Sun Aug 14, 2022 10:26 pm

telford dorr wrote: Fuse boxes with a ground bus are for use on boats (which are generally made from non-conductive materials). Gives a convenient place to connect the ground wire from loads. Not needed on a bus. :thumbsup:

aeromech Sun Aug 14, 2022 11:17 pm

I’ve installed several aux fuse panels. I like Blue Sea because it’s marine grade. Having a ground on the fuse panel is fine but not required. There are lots of things up front that need power and ground like a car stereo, fog lights, cigarette lighter, gauges, etc. you can ground to the chassis or ground to the aux fuse panel. Up to you.

My advice is to use the Blue Sea components like ACR and battery switch. I’ve posted several pics here in various threads so just do a search. If you need advice send me a PM and I’ll help you.

Later-Gary




Oil Phil-M Mon Aug 15, 2022 2:55 pm

My aux fuse box is a standard bus fuse box mounted up front in the mirror image location to the existing fuse box. The bottom mounting tab needs to be bent in the opposite direction then it bolts in nicely. Use it for interior lights, stereo, 12v power outlets, aux heater, hazard lights. Also the way the box is set up I have some of the fuses wired from the main battery to power front and rear fog lamps.

SGKent Mon Aug 15, 2022 5:41 pm

here is what I did. The photo is from a thread on trimming the VDO gauges to the other lights. In the image there is also an aux fuse box mounted next to the main one.


Mberglo Mon Aug 15, 2022 7:11 pm

Just do the chassis ground. No sense in running long wires back to a ground bar.

nemobuscaptain Tue Aug 16, 2022 3:40 pm

Ideally the fuse box should be close to the battery, or the hot wire from the battery that feeds the fuse box should have its own fuse (or mega fuse, fusible link, whatever).

orwell84 Tue Aug 16, 2022 4:26 pm

I think the issue is that when you have a lot of gauges, for example, it gets messy grounding all those wires. Each gauge has 2, 1 for the gauge and the other for the lighting. Instructions usually tell you to ground each separately, so you find random screws in the bodywork and what a mess.



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