Fuses - what do the ratings mean?

[HeatedGrips]

I've just fitted an auxiliary socket wired direct to the battery because the canbus one won't work with my heated jacket.

The socket came with a 5amp in-line fuse, but the current ate that one immediately, so I put in the one that came with the Gerbing jacket which is a whopping 15amps.

By my, admittedly not very expert calculations, that means the jacket can take up to 180 watts before anything pops, which seems rather a lot.

When a fuse is rated at 15 amps does that mean it blows at that current level - or does it have to go higher than 15?

 

[John Armstrong]

Information here: http://www.circuitprotection.ca/fuseology.html which is probably more accurate than my thoughts

 

[Greg Masters]

Fuses are there for a reason. If your heated jacket is blowing a 5 amp fuse - find out why!! Replacing with a higher-rated fuse is a recipe for disaster.

Most heated jackets should take less than 60 watts - the jacket might even specify its current usage.

Greg

 

[GSmonkey]

Yes - you will require more than the rated current of the fuse to blow it. How quickly it blows at higher current levels depends upon the characteristic of the fuse that you choose to use. At say 15.1A, it may take 12hrs to blow, but at 20A it could well blow in milliseconds.

For the case in question you say that the Gerbing jacket came with a 15A fuse. That is therefore good indication that this is the correct fuse for the jacket. You should probably refer to the jacket's instructions to check.

The problem you seem to have is with the socket. If this came with a 5A fuse, it may well be that the socket and wiring may only be rated for 5A. Running with a 15A fuse, could lead to a fault with the socket. Again you should check with the instructions.

 

[HeatedGrips]

Just looked on the Gerbing website and they say their jacket only uses 77 watts, so I'm going to try a 10-amp fuse for peace of mind.

Does that make sense?

 

[GSmonkey]

Sounds good. Always use the minimum fuse you can get away with.

 

[Wapping]

Fuses are there for a reason. If your heated jacket is blowing a 5 amp fuse - find out why!! Replacing with a higher-rated fuse is a recipe for disaster.

Most heated jackets should take less than 60 watts - the jacket might even specify its current usage.

Greg

Most of Gerbing's gear seems to be 6.4 amps / 77 watts.

Whether that's average or from cold it doesn't say. It would explain though why it overwhelmed the 5 amp fuse and, of course, the canbus aux socket.

 

[Droopy Dick]

Most of Gerbing's gear seems to be 6.4 amps / 77 watts.

Whether that's average or from cold it doesn't say. It would explain though why it overwhelmed the 5 amp fuse and, of course, the canbus aux socket.

If you use their natty heat controller, once you're nice and warm you can turn the controller to a lower setting. This mean the jacket draws less current.

In other words the current draw depend son how 'high' you turn the knob.

 

[Greg Masters]

Most of Gerbing's gear seems to be 6.4 amps / 77 watts.

Whether that's average or from cold it doesn't say. It would explain though why it overwhelmed the 5 amp fuse and, of course, the canbus aux socket.

Fair enough.

But, as suggested, I'd check why the socket has a 5A fuse.

Greg