Need help choosing fuse

Hi fellow reprappers, I have a quick question. I bought a 12v 30a psu for my 3d printer project and now I have this little dilemma where I would like to add a switch to turn it on and off instead of the ol remove from socket jig lots of people have going on. my problem is choosing the right fuse for the on and off switch. given that the psu is rated 12v and 30a using a a 110v outlet means I should be using a 115v on and off switch right? or is it safe to use a 250v on/off switch with a 10a fuse seeing as theyre double the capacity. here are the links to the fuse, on/off switch and the psu

On/Off switch

10a Fuse

12v 30a psu

thanks for your advice guys. I am hoping to take an electronics class next semester seeing as I will REALLY need it

Yes you can use that mains inlet plate, but I would put a 5A or 6A slow blow fuse in it, not a 10A quick blow. You can print a cover to enclose the mains wiring. Here is the one I use: [www.thingiverse.com]

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I found this on Thingiverse - and have printed one for my PSU. I use a separate fuse and enjoyed the safety and aesthetic aspects of this simple solution.

[www.thingiverse.com]



Richard

wow thanks for the thingiverse model! that's an awesome design. I was worried about getting shocked lol!

hey DC, darn I ordered the ones on the link :/. would they be ok for now? or should I go and order the slow blow fuses? im short on funds but if its really needed then I will do it. thanks!

You may find that the 10A quick blow fuses blow when you first turn the switch on, because of the surge when the power supply starts up.

If you use that cover on Thingyverse, you must secure the mains cable somehow so that the connections to the terminals of the power supply are protected from stress.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

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dc42
[snip]If you use that cover on Thingyverse, you must secure the mains cable somehow so that the connections to the terminals of the power supply are protected from stress.

I used a plastic P-clip screwed to the frame for that.

Richard

Hey Richard, do you think its good if I just sand the little areas down a bit until I get the perfect groove for each wire? thanks

Dc42, hey man, bummer that I already ordered the item. but I will get the one you suggested because id rather have a working machine off the bat. thanks for your input guys!

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RGN01

Quote
dc42
[snip]If you use that cover on Thingyverse, you must secure the mains cable somehow so that the connections to the terminals of the power supply are protected from stress.

I used a plastic P-clip screwed to the frame for that.

Richard

how do you setup the clips?

Quote
dc42
You may find that the 10A quick blow fuses blow when you first turn the switch on, because of the surge when the power supply starts up.

If you use that cover on Thingyverse, you must secure the mains cable somehow so that the connections to the terminals of the power supply are protected from stress.

hey so im going to buy these fuses. what do you think of them. I don't know how to find the 6a slow blow fuses properly so I just stuck to these I found by the same supplier

10A slowblow fuse link

if you have a link, ill check it out. thanks for your time

Looks like 6A is not a common rating, but 5A and 6.3A are. Both are widely available on Amazon. 5A will be sufficient for your printer.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

hey thanks. so any fuse that's 5x20 5a or 6.3a will do?

5a

will these work?

Edited 1 time(s). Last edit at 06/05/2015 04:28AM by davedavedave.

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davedavedave
hey thanks. so any fuse that's 5x20 5a or 6.3a will do?

5a

will these work?

Those are 2.5A. You need 5A or 6.3A.

You could try your existing 10A quick blow fuses first, you may find they are OK, or only blow occasionally (and probably only when you turn the power on).

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

ah ok. ill try them but I have some new ones coming that are slow blow. thanks a lot for your input man itll probably save me a lot of headache later

This appears to be this power supply: [www.mouser.com]

The running current is 6.5 amps and starting surge current is 50 amps. A rule of thumb says to fuse at 150% of running load and that is now 10 amps. To handle a starting surge of 50 amps, it may need a delay fuse.

Remember, a fuse is not to protect the downstream device, it is to protect upstream of the fuse from a failed downstream device.

i am not sure theyre the same. the one I have is called a "supernight" psu. its a 12v 30a psu. whats the difference? does the one in the link you posted a 12v 50a? would that mean I wouldn't need a relay for the heatbed if the heatbed is 16x16? thanks




also, dc42, I found these fuses 5a slow blow