Fuse rating, help!

[Jordan]

I just finished loading my new mixer and outboard rack which consists of behringer ub2442fx mixer, 1 x behringer composer compressor, 2 x apex dbqzero dual channel 30 band graphics and a gemini cd player. These are all powered from a 1u fused sequential start power distro.

 

When I came to load fuses into the distro I realised I didnt know the correct ratings for each unit. The manuals dont tell me and looking at the various kettle leads these have been fed with before didnt help either as they have all come from various places and have a real mixture of fuses in them including to my horror a couple of 13 amp ones.

 

So at the moment I have put 5amp fuses in them all but I am wondering if some or all of them should be on lower ratings.

 

Any advice would be welcome.

[david.elsbury]

The user manuals that come with each piece of equipment (or should be available online in the event you have lost the manuals) should give you the current draw for each unit.

 

The primary purpose of the fuse is to protect the cabling connecting the equipment from drawing a higher current than it should.

The primary purpose of the fuse is to protect the cabling in the event that there is an electrical fault, as otherwise there is a risk that the cable will melt from having too high a current drawn through it.

 

In my opionion (without seeing the cable in question) you should be fine to fuse at 5 amps since the cable is probably 0.75mm2 or bigger.

 

But as always, if you have any questions, probably best to consult your friendly local qualified electrican.

 

(Edit: replaced the strikethrough text above, for clarity... sorry- I know it's not good to edit after a post has been replied to :D)

[Jordan]

The user manuals that come with each piece of equipment (or should be available online in the event you have lost the manuals) should give you the current draw for each unit.

 

The primary purpose of the fuse is to protect the cabling connecting the equipment from drawing a higher current than it should.

 

In my opionion (without seeing the cable in question) you should be fine to fuse at 5 amps since the cable is probably 0.75mm2 or bigger.

 

But as always, if you have any questions, probably best to consult your friendly local qualified electrican.

 

Cheers for that David. I didnt realise the fuse was to protect the cabling. That makes sense as all these items have a built in fuse also which protects the equipment. And yes, the cable is 0.75mm2.

[TCSC47]

If the current taken by each unit is not written on the equipment, then at least the power taken will be. Use I = P/V to calculate what the curent should be and choose the fuse above that current.

where I = current in amps, P = power in watts. V = 230V

[adam2]

5 amp fuses should be fine in practice, even 13 would probably be OK in practice.

Remember that the same equipment is almost certainly sold elswhere in Europe, and equiped with unfused plugs intended to be inserted into outlets on 15,16 or 20 amp circuits, and no one worries about that.

The purpose of the plug fuse is to protect the flexible cord against short circuit, if the appliance requires better protection then it should incorporate suitable fuses or circuit breakers.

 

Research has shown that 0.75mm flex can be protected against short circuit (though not of course against overload) by a fuse or MCB of up tro 20 amps.

0.75 mm flex is used throughout the world on unfused plugs on 15,16,or 20 amp circuits, and is considered safe, and is CE or UL marked.

 

Such flex can not be protected against short circuit by the 30/32 amp fuses used for UK power circuits, which is why UK plugs have fuses in them.

[KevinE]

I'd have stuck 3A in each.

[Jordan]

Thanks all for your input, some very useful info there.