Fuse Taps at 30amp with 16AWG....

[Paul Curtis]

Hi,

Looking to pull power for a 30amp amp from the fuse box of a BMW X1. The easiest way to do this is to use a fuse tap with a 30 amp fuse, that means not having to mess with behind the fusebox and makes it easy to swap and change.

The only fuse taps that I've been able to find though - which say they are rated for 30 amp - are 16AWG wires coming off them. The power cable that I would route to the Amp at the back is 8 AWG.

So connecting 8AWG to 16 seems pretty difficult. I was thinking of using an inline fuse as the connector, so that would be 2 x 30amp fuses. Can't see that being an electrical issue but it's not ideal really.

But really is that 16AWG over a 10cm length going to be okay? In the fuse box itself I don't see huge thickness of wires and BMW themselves are not using huge AWG cables everywhere either.

Or is there such a think as a fuse tap with something closer to 8 AWG?

Many thanks
Paul

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[maylar 10+ year member]

Bad idea. 16AWG is a 10 amp wire. Do it right - tap into the main power feed under the hood near the battery. Yes, it's a lot of work.

 

[Paul Curtis]

Bad idea. 16AWG is a 10 amp wire. Do it right - tap into the main power feed under the hood near the battery. Yes, it's a lot of work.

Fair point.

Although way easier to pull from the actual fuse box? There are 50 amp fuses in that fuse box and so it has the main line to the battery?

In the box itself there are many slots which have the positive rail and no fuses in. Either I manage to get in behind the fuse box panel to get the wire in there or I take it from the front with an inline fuse and some kind of connector.

Getting to the battery in the X1 (UK model so in the front) seems quite awkward as there is a massive BMW connection system on there and a lot of the connectors are empty - difficult to get to the battery.

thanks
Paul

 

[spokey9 5,000+ posts]

Shortcuts + electricity = a bad time

 

[maylar 10+ year member]

Typically there is a fuse "box" under the hood where the battery voltage gets distributed through big fuses to the vehicle. You would use a 30 or 40 amp fuse holder that attaches to your 8 ga wire and gets bolted to the distribution block with a big ring terminal. You don't have to go directly to the battery itself.

 

[maylar 10+ year member]

Although way easier to pull from the actual fuse box? There are 50 amp fuses in that fuse box and so it has the main line to the battery?

Yes.

 

[dragon.breath 10+ year member]

Go to the battery directly. Period.
I know a person who tried to wire an amplifier to the fuse box. I told him that it was a bad idea but he did it anyway. I drove by his house a week later and the burnt hull of his truck was sitting in the driveway. Not Kidding.

 

[Paul Curtis]

Typically there is a fuse "box" under the hood where the battery voltage gets distributed through big fuses to the vehicle. You would use a 30 or 40 amp fuse holder that attaches to your 8 ga wire and gets bolted to the distribution block with a big ring terminal. You don't have to go directly to the battery itself.

Yes, but often on the BMWs there are no spare 'slots' for adding anything to the fuse 'box' on the battery. But there is the actual fuse box inside the car at the back of the passenger glove box. This is where the 30 amp fuse for the factory Amp would normally be, but I don't have that just the base audio. That box has fuses from 30 to 50 amp in and working now.

So there are lots of unused slots on this fuse board and I can see the positives are all connected on a rail (I bought an old one off eBay to look at and understand) but only the slots that have cables have the spring clips in on the other side (makes sense).

So either I pull the board out, turn it over and get a double spring clip connector and use one of the existing stock fuse sites (but this looks very awkward to do without dismantling a lot) or I thought ah a fuse tap would be ideal. Of course 16 AWG isn't going to work but I have found some with 12 AWG. Looking at the board itself most of the factory cables coming out of the 30 and 40 amp fuses are probably 14 or 12 AWG, they are certainly not 8 or 10.

So a 30 amp fuse tap into a 30 amp inline fuse that also handles the junction between 10 cm of 12 AWG and the longer run of 8/10 to the Amp. This is not a crazy powered amp, just 550w.

Or is there a dummy fuse connector made that has a breakout wire off it.

It's a lot easier to install something that slots into the existing box without the dangers of removing it and fiddling with it. That was my attitude. Keep it simple so long as it's safe

cheers
Paul

 

[Paul Curtis]

Go to the battery directly. Period.
I know a person who tried to wire an amplifier to the fuse box. I told him that it was a bad idea but he did it anyway. I drove by his house a week later and the burnt hull of his truck was sitting in the driveway. Not Kidding.

Can't argue with a fire! What was he trying to hook up?

 

[spokey9 5,000+ posts]

Go to the battery directly. Period.
I know a person who tried to wire an amplifier to the fuse box. I told him that it was a bad idea but he did it anyway. I drove by his house a week later and the burnt hull of his truck was sitting in the driveway. Not Kidding.

Whats a few flames between friends

 

[Deiimos]

Yeah be careful how you go about this, while fires may be somewhat rare, it is a hazard if something isn’t done correctly and can happen. Connecting directly to the battery is how this is supposed to be done, with proper fuse added near battery of course.

Perhaps let a professional shop install the wire for you. Then maybe you can install the rest yourself?

 

[dragon.breath 10+ year member]

Can't argue with a fire! What was he trying to hook up?

It was a powered 12 inch subwoofer. I don’t remember the exact one. It has been a while.

 

[maylar 10+ year member]

Although way easier to pull from the actual fuse box? There are 50 amp fuses in that fuse box and so it has the main line to the battery?

Thinking about this... Yes there would be a direct connection to the battery. The question is, how is that feed supplied? For 50 amps you would need the equivalent of 8AWG wire. Auto makers often use multiple runs of smaller wire in parallel. For instance, 2 x 14 AWG would be the same. If the feed wire(s) from the battery are bolted to the fuse box, that would be a handy place to attach your cable.

 

[Paul Curtis]

Thinking about this... Yes there would be a direct connection to the battery. The question is, how is that feed supplied? For 50 amps you would need the equivalent of 8AWG wire. Auto makers often use multiple runs of smaller wire in parallel. For instance, 2 x 14 AWG would be the same. If the feed wire(s) from the battery are bolted to the fuse box, that would be a handy place to attach your cable.

I bought a second hand fuse board off eBay to pull apart and check. There is a massive AWG 0 or 1 cable that provides the main source. So I don't think there are any issues with load to the fusebox. The cables coming off the fuse box differ depending on their Amps.

There's a slot for a 30 amp fuse for a built in Amp and I was planning on taking a feed from there. I would say that BMWs cables are less than what I believe the recommended AWG should be for a given load but they'd have done this 100,000s of times and ought to know.

Once I get some spring loaded clips for the box then I will most likely 'do it properly' in the sense of add a link to the back of the board and run it like a factory installed one rather than a fuse tap

Kindest
Paul

 

[Old_Slapper]

I made a lot of money repairing fuse boxes that were destroyed from people taping into them. Pay once by doing it right. Do it wrong, the second payment will be quite a bit more than the first time you paid it.