Power tap from inside W212

[ASmithI]

The car is a 13 Plate W212 E250 facelift.

I am looking for an all the time on power source for a security device to be placed inside the car. The power rating of the device is only 100 mA. I have checked the fuse box at the left of the engine compartment. But the wiring work is so tidy that I can't find an opening through the firewall to slip in even a single wire. Tapping from the fuse box in not an issue.

So I found that bunch of wiring in the front passenger foot well as pics show. I have probed that single larger red wire and it is carrying 12V with the ignition off.

My question is, would there be any risk of disturbing the car electrical system if I make a tap from that red wire? My loading will be 100 mA at most.

Comments please.

 

[kjl]

I cannot answer your question but you will find an always on spare live terminal in the fusebox in the boot on the right hand side. I got an inline fuse holder and on one end soldered a spade terminal which I pushed into one of the spare fuse terminals which was live. Connect the other end to the item you want to power and then you will need an earth wire from the item to a suitable earth point.

 

[ASmithI]

Thanks for your comments, kjl. Looks like it is not advisable to meddle with power tapping from an internal source. I will explore the method as discussed in the thread below which is finding a way through the bulkhead out from the driver's footwell and making a proper fuse tap connection for power.

http://www.mbclub.co.uk/forums/bodywork/198668-bulkhead-thgrough-holes.html