I've just ordered a multi cigarette lighter socket like this, which I intend to hard wire to the car, it will be used to run a dash cam and for phone charging, what size fuse would you recommend i use?

what is that power consumption of the stuff you are pluggin into it?

 

for something like a camera of phone carger i wouldnt go bigger than a 5 amp fuse, i'd be tempted to take that from a switched feed in the fusebox so that it goes off when the key is pulled out

There should be a fuse inside the plug. Use that rating.

Thanks guys, I've got a picture of the fuseboard that someone kindly posted in the mk1 octy section, so I've got my earth and switched live sorted, I'll see if there is a rating on the unit when it arrives.

I added two extra sockets and use one for phone charging and one for sat nav both are fine with a shared 5 amp fuse. You are looking to have the lowest rating fuse you can get away with. But most important is that the cable used for the wiring has a greater rating than the fuse.

Edited 2 August, 201312 yr by paddypaws

For my Blackvue I use a 1amp fuse. You might be surprised how little those things draw. Most phone chargers are only a couple of amps tops anyway, so a 5 will be more than enough. I personally wouldn't use anything larger.

Each 'cigar' plug has a fuse inside that should be the correct rating. If you unscrew the tip collar, the fuse will pop out.

Each 'cigar' plug has a fuse inside that should be the correct rating. If you unscrew the tip collar, the fuse will pop out.

Spot on, little 5 amp fuse inside.

On my wives Fabia and my old Octy I used a 5A.

Much nicer having it all wired in

UNKNOWN, BUT-  it's simple OHMS law ,and a bit of Maths.

 

Watts = Amps ( taken by appliance) times Volts ( in this case nominally 12v).

So ,by transposition , Watts /12 = Amps .

So if appliance has a 12W rating, it takes 1A, and I'd suggest a 1.5/2A FUSE. ETC. So for every 12w of rating you need to add 1A TO THE FUSE.( i'D ADD 1.5, possibly even 2A if appliance has a high start up surge ).

It's not majic or rocket science.

Seem to remember the cigarette lighter has a 20A fuse or might be a 25A.

More than enough to run those items mentioned which on use an Amp or so.

I plug an DC/AC invertor in to and it does blow the fuse some time just on startup so I use a fuse 5A bigger than what was in there and it seems to be fine.

Important thing to remember above ALL, is the size of the cabling you are supplying the item with, you rate fuses to protect the cabling above all, not the equipment. If you can manage to protect both, ie. a cable capable of carrying say 5A , protected using say a 2A fuse, (which could be the maximum current demand of the equipment being used) then you are onto a winner because this way you are protecting both sufficiently.

 

As far as auto fuses however, their ratings are slightly different from your standard fuses andso, a 20A autofuse / bladefuse will not necessarily blow at exactly 20A but instead at say 21/22A, which means they can sit at 20A all day long and if the equipment/cabling is to be protected at no more than 20A can cause substantial damage.

 

Another quickie also, the rating of your plugs, be it 13A domestic or even your standard cigarette lighter plug, the ratings printed on these are the maximum current they are designed to operate within, not necessarily what you should be fusing them at.

 

Hope this helped

 

Paul.

 

 

Thanks for all the comments above, the only reason I asked was because I was chopping off the plug, which I assumed was fused somehow, didn't realise it would be as simple to find out as it was.