Led stripe. What size fuse?

[cmedsailor]

I have bought a 2.5m length led stripe that I plan to connect directly to the batteries (I will include an on/off switch too). I believe the addition of a fuse on the positive side is a must. Could you tell me what size fuse (how many amp) is necessary?
Thanks

 

[nigelmercier]

The best way to find out is to measure the current, then add a bit.

 

[Kwik Decision]

The key purpose of a fuse in this case is to protect the wireing to the light, so that if there were a fault the fuse would blow at a current flow below that which would cause the cable to overheat and ultimately catch fire. Therefore the size of fuse you need depends on the size of cable you are using. If you use 0.5 mm2 cable, this has a current rating of 11 A, so your fuse should be no bigger than this, but could be significantly smaller; I'd use a 3 or 5 A fuse in that case. More details here:

http://www.12voltplanet.co.uk/cable-sizing-selection.html

And if you look at the cable for sale section, it gives you the max current for each size.

 

[cmedsailor]

Thanks to both. I am wondering if there are any fused switches to avoid many connections. I think there aren't any with so little amp.

 

[sarabande]

what about a small fused switch panel, possibly with MCB ? Or adapt a bilge pump switch which looks quite neat.

http://www.ebay.co.uk/sch/items/?_n...&LH_CAds=&clk_rvr_id=1028783009021&rmvSB=true

 

[alahol2]

Just as an aside, at 2.5m that's a long strip. You will probably need to drive it from both ends otherwise you will have one end dimmer than the other.

 

[Hoolie]

I don't think so! I have 2x5m strips on board and there is no noticeable difference one end to the other, though I hardly ever run them at full brightness.The dimmer is a variable mark to space device and any difference one end to the other would be noticeable at any light level.

 

[nigelmercier]

... the size of fuse you need depends on the size of cable you are using...

That old chestnut surfaces again. Will it never die?

The size of fuse is determined by the lower of the cable and the internal wiring of the device. Therefore I suggest you do what I suggested above.

 

[myquest]

That old chestnut surfaces again. Will it never die?

The size of fuse is determined by the lower of the cable and the internal wiring of the device. Therefore I suggest you do what I suggested above.

I love old chestnuts! What the eff is "the lower"?

 

[macd]

I love old chestnuts! What the eff is "the lower"?

He might more accurately have written something like "the lower of the ratings", but perhaps to demand that in the way you did is a little obtuse?

 

[David2452]

Nigel is probably as exasperated as I am by the misleading and potentially dangerous mantra that an over-current device is there to protect the cable, it is not, it is to protect the circuit (which includes but is not limited to the cable) and should be sized to protect the rating of the component with the lowest max current value downstream of the over-current device in the circuit.

 

[Tammany]

Just had a look around and they are rated at around 5w/meter so ideal fuse is 1.04A so a 2 or 3A fuse would be sufficient. Personally I would use a blade fuse as the holders with covers are cheap on ebay and the fuses are easy to come by.

 

[cmedsailor]

Just had a look around and they are rated at around 5w/meter so ideal fuse is 1.04A so a 2 or 3A fuse would be sufficient. Personally I would use a blade fuse as the holders with covers are cheap on ebay and the fuses are easy to come by.

Actually the smallest blade fuse I have found is 10A and I will use that one. I can find smaller round ones (like a cylinder) but I really hate their fuse holder.

 

[Tammany]

Ebay or

http://www.autoelectricsupplies.co.uk/product/287/category/157

 

[Tammany]

10A would be ok, if it goes short it's gonna blow before anything bad happens unless the wire is very thin.

 

[nigelmercier]

Actually the smallest blade fuse I have found is 10A and I will use that one...

So you ask what size fuse, get an answer of 3A, then decide to ignore this and go for one that is rated much too high.

 

[cmedsailor]

So you ask what size fuse, get an answer of 3A, then decide to ignore this and go for one that is rated much too high.

I have just realised that I typed 10A instead of 5A (the fuse I have). In any case it's always good to know what is correct despite if I don't follow it.