adding-a-mains-power-switch [Bukobot 3D Printer Instructions & Docs]

(Up to [[user-created-add-ons]])

Here are some options for adding mains power switches to your Bukobot.

**As always when dealing with mains voltages, safety is paramount.** If you don't know what are you doing then best wait until instructions are finalized and reviewed.


===== Illuminated power switch, IEC plug and fuse. =====

You can buy an integrated illuminated switch, IEC socket and fuse module here: http://www.amazon.com/Inlet-Power-Socket-Switch-IEC320/dp/B00511QVVK/ref=sr_1_cc_1?s=aps&ie=UTF8&qid=1349228924&sr=1-1-catcorr&keywords=Inlet+Male+Power+Socket+with+Fuse+Switch+10A+250V+3+Pin+IEC320+C14 
[There are also plenty of vendors selling them on Ebay if you are not in the US.]

You will need to buy a 20mmx5mm mains fuse for this module as well. The fuse should ideally be Slow Blow and at least 2-3x times the current rating of the supply in order to handle start up surge currents (Current = Watts / Mains Voltage). E.g., for a 350W power supply at 240V it only has a max load current of ~1.5A but you would want at least a 4 amp fuse. I tried a 5A fast blow fuse for this supply and that seemed be able to handle the inrush current (I didn't have any slow blow fuses at the time). Also remember to double the current if you are halving the supply voltage (i.e., 10A for 115V).

You can find the power supply cover design files here to fit it on the power supply: http://www.thingiverse.com/thing:31659 [Kudos to NewtonRob for the original idea.]

When wiring the module, you need to connect the neutral and active terminals of the socket to the slightly narrower set of switch terminals. Depending on how your switch was assembled these could be either on the right or the left hand side. The corresponding terminal on the other side of the switch is then connected to the same active or neutral power supply terminal.

In the picture below, active is brown and neutral is blue (as is the standard).

{{:powerswitchwiring.png?800|}}

If you look carefully in the above picture you can see the neon lamp is connected to the slightly wider set of terminals on the right-hand of the switch (this comes preconnected). If you got it wrong and connected the wires from the socket to these terminals then the neon lamp would simply be permanently on. On the other hand, it should not matter whether the active or neutral is connected to the top or bottom set of switch terminals just as long as the other side is correspondingly connected to the power supply.

===== Other ideas =====
  * Here is another IEC socket and power switch solution which doesn't use an integrated module. http://www.thingiverse.com/thing:30011
  * And another fully enclosed power supply cover design and power socket (but no switch): http://www.thingiverse.com/thing:30072

===== Other comments =====
  * If you are not using an IEC socket or similar, then it is highly recommended that all connections to external mains cables have some form of cable strain relief so that the connection doesn't weaken with movement of the cable or the connection won't be strained/pulled out if someone trips over the cable. [Strain relief could be as simple as using a cable-tie through the grille holes of the power supply to anchor the mains cable.]
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