Are fuse positions with only one pole still usable?

[RiffRaffMama]

I want to use my fuse panel to hardwire a dash cam so I don't have to go tracing and hacking into wiring. This dash cam has parking mode, so it needs a constant keyless power supply like brake lights, headlights, horn, etc. I know I can use a fuse tap, but I have an empty fuse position I'd rather use if possible. The only (potential) problem is that it only has a metal clamp thing on one side of the slot (those things that grip the blade of the fuse, usually located on both sides of the slot - see pic).

The single clamp thing has constant 12V power, so I figure it is positive. Would this be a suitable location to tap into the power supply for the cam, or do I need the negative clamp as well? Wouldn't the negative side just go to ground anyway?
The empty position is labelled "sub woofer" and is immediately beneath the radio fuse. I do not have a subby, nor do I have any desire to obtain one, so I'm not going to be using that slot.
I don't know if it's meant to have two clamp things and one has just buggered off at some point in time, or if that is standard issue for that slot. So is it usable in its current state as a power source for my dash cam?

 

[Grimes]

It should be OK. The cam has its own earth and fuse. The point you’re using is no different to splicing into a powered wire anywhere else.

 

[shane_3800]

The power wire should be fused at the box so not the best idea.
Also if you fuse the wire you need a big enough power wire to blow the fuse before catching fire.

Dash cams don't draw very much amps at all so you can just splice into most power in the dash.

 

[Immortality]

Use something like this,

And this,

Plug it into the spare socket in the fuse panel and you have a fused power supply (assuming the pin you mentioned has power with the ignition off.

 

[Grimes]

The power wire should be fused at the box so not the best idea.
Also if you fuse the wire you need a big enough power wire to blow the fuse before catching fire.

Dash cams don't draw very much amps at all so you can just splice into most power in the dash.

Dash cams generally have 2A glass cylinder fuses built into their power and accessory leads so he should be OK.

 

[shane_3800]

Dash cams generally have 2A glass cylinder fuses built into their power and accessory leads so he should be OK.

That does not protect the wiring as that is the point of having the fuses near the battery.
This is why fuses aren't spread out accross the car at the components.

Think about it in your house if you have an amp it might have a fuse in the back but that doesn't mean you don't need circuit breakers.

 

[Immortality]

My way puts a fuse at the fuse panel

 

[Grimes]

My way puts a fuse at the fuse panel

I don’t disagree with either of you, but for a dash cam the spade fuse does little because they start at 3A. When there’s a 2A fuse a bit further along the cams power wire, the 3A spade only offers down-to-earth protection for a rub through on the cam power wire between the spade fuse and 2A cam fuse.

All that said I’d still use the fuse tap because it’s the tidiest solution.

 

[shane_3800]

I don’t disagree with either of you, but for a dash cam the spade fuse does little because they start at 3A. When there’s a 2A fuse a bit further along the cams power wire, the 3A spade only offers down-to-earth protection for a rub through on the cam power wire between the spade fuse and 2A cam fuse.

All that said I’d still use the fuse tap because it’s the tidiest solution.

This is why I said use a large enough gague of wire to be able to trip the fuse.

With my cam I cut the USB cable off as short as possible and ran the rest in 2mm square. If you shorten a undersize cable you have more chance of tripping the fuse as the shorter the wire the more amps it can take. Also the shorter the cable the less chance of damage occurring.

 

[vc commodore]

Dash cams generally have 2A glass cylinder fuses built into their power and accessory leads so he should be OK.

Not the 2 dash cams I have.....My first dash cam runs from my cigarette lighter, whilst the 2nd one runs from a USB port I have fitted, with a 5 amp fuse in the boot of the car...

Both dash cams are under 12 months old too