Hi i have a Garmin 55 dashcam with the cable but the garage i normally use want £50 to fit it. This is three wires and i am going to try to do this myself but i need a fitting guide. If anyone can help or fit it cheaper. I’m in the Norfolk area.

 

my car is a Octavia Vrs diesel 59 plate. I know i sound like a tightar*e but I’m just having to find the cash as someone decided to reverse into my front wing and just drive away.

 

Any help would be appreciated.

A search on this forum shows many threads on the subject.

This threads is the best place to start as it has photos. Note this probably the longest thread on the forum but most of the info is at the start.

 

 

 

Basically, you unclip the cover over the A pillar and run a cable from your selected position for the dash cam down to the fuse box at the right hand end of the dash. It is likely your dash cam needs 5 Volts rather than 12V so you need to add a small converter  which can be hidden in the fuse box area. You will also need a piggy back fuse holder for the fuse box as shown about half way through this long thread. Make sure the add on fuse is no bigger than half the current rating of the wire from the dash cam. I suggest no bigger than a one Amp fuse.

 

Not a difficult job but helps if you have some electrical experience.

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Make sure the add on fuse is no bigger than half the current rating of the wire from the dash cam.

How would you work out the current rating of the wire from the dash cam?

And why would the fuse need to be half that?  Wouldn't it then blow if the dash cam uses the potential of the cable?

 

(no electrical experience here )

It is a common misunderstanding that the fuse is there to protect the unit being supplied. That is true only in certain specific circumstances. The real reason the fuse is there is to protect the cable from overheating under fault condition such as a load fault or a short to ground. 

The supplier of your dash Cam will have printed in the documentation or on the unit itself, the supply voltage and current draw. It is the law.

If they supply a cable then it must be rated for the at least the current draw of the unit.  This gives you an indication of the fuse size for a direct connection.

If your dash cam is needs a 5V supply then you will need to buy a converter from 12V to 5V. The current draw on the 12V  side will be roughly half the current taken by the dash cam as it is (5/12) times the dash cam current plus the losses in the converter.

If your dash cam needs a 12V supply then use the published current draw figure for choosing the minimum cable size and fuse. For example, if it draws half an amp then use a 2A cable and a 1A fuse since 2A cable is easy to handle and more robust than smaller sizes. You could of course use an even larger cable if you wish.

ah, never knew that, thanks.

 

So if the supplier of a device supplies a 2amp device, and a cable that's also 2amp, you wouldn't want a 1amp fuse for that would you? 

I'll check my dashcam out - will be interesting to see.

4 hours ago, gsf600y said:

ah, never knew that, thanks.

 

So if the supplier of a device supplies a 2amp device, and a cable that's also 2amp, you wouldn't want a 1amp fuse for that would you? 

 

 

Not if everything runs at 12V, but if the load runs at 5V and takes 2A using a voltage converter, then since the Watts are the same at both voltages, the current will be proportionately lower at the 12V end, plus a small additional current for losses in the converter.

In practice you may use larger cables throughout and a larger fuse as long as the fuse still protects the bigger cable by blowing before the cable is damage by the fault current.

However, although the converter should be self protecting against internal faults (typically a weak link on the PC board) I would not trust some imported products which, although CE marked, do not meet CE standards. Therefore I have always designed systems for minimum fault currents and use the smallest fuse that works.

 

I often see people saying they have taken cables directly from a car battery to a lighting relay or sound system and not put in a fuse, or only put in a fuse at the load end. No protection for the cable if it shorts to ground, say over a sharp metal edge. I wonder how many car fires are started by this diy wiring?

 

 

 

 

FYI, I have fitted cheap front and rear HD DVR car cams by mounting the cameras on their respective screens and then running the power supply cable to the passenger "B" pillar and down to the floor by pushing the cable under the plastic trim and the door rubber, I have then used a multi socket from the accessory socket in the middle of the car to connect the camera leads, by doing this albeit a chore I can connect or disconnect them as required, id does mean the plugs and socked are seen beside the passenger door and seat but I don't see that as a problem and for me it is a cheap fix as when a camera fails it is easy to replace.

Didn't need to remove any panels to fit the wiring for my front mounted dash cam. Used a plastic tyre lever for a bike to gently push and tuck wiring being trim panels.

Use a 12v multi adapter behind the trim in the front passenger footwell that also powers 2 phone chargers, blue tooth hands-free and usb socket to rear passengers