Wiring Questions

[markronz]

Hello everyone-
    I will soon be wiring up all the various LEDs in my cabinet.   Three items are 5v and two items are 12v.    I need to split the wires coming from the power supply to go to the different LEDs.    To do this, I will be using barrier strips in conjunction with some jumpers.

I will be using one barrier strip/jumper to split the 5v power line into three separate wires.
I will be using one barrier strip/jumper to split the 12v power line into two separate wires.
And lastly, I will be using one barrier strip/jumper to split the ground wire into 5 separate wires.
I will be connecting all of these wires with spade connectors (forks) to the 5v/12v power supply from Twisted Quarter.


1.  Does this sound like an acceptable way to wire everything up?   Seems pretty straight forward, but I wanted to make sure that was all cool before I wired it up...

2.  Do I need to cover up the barrier strip/jumpers at all as far as it being in the open and shocking someone?  I didn't think 5v or 12v would be anything to worry about, but I wanted to make sure.   I mean, the barriers are inside the cabinet, and people should never be digging around in there (besides me occasionally), so I wouldn't think it'd be an issue either.    If you think it'd be wise to cover these up, is there any way I should do that?  Just didn't know if there was some special way to cover these barrier strips, or insulate them...

3.  Now the LEDs themselves will obviously have a ground wire attached to them, as I previously mentioned I will be splitting the ground wire coming from the power supply.  But my question is, do I need to ground the power supply itself?  I just know that I've seen on other devices where people will have an additional wire running and connects to something metal, like a bolt or something within the cabinet.  Is this necessary?

Thanks for the help!  Let me know if you need more details or if any of my questions are not clear!

[zafdor]

1) should not be a problem

2) the 'official word' for UL/CSA is voltages under fourty something volts is considered Safety Extra Low Voltage (SELV) and is not a shock hazard.  However if these ENERGY LEVEL is high enough it can be considered an ENERGY hazard, this happens at levels above 240Watts.   If your 12V PS output is above 20A or the 5V winding is above 48A, it would be considered hazardous energy.   An example of a hazardous energy mishap might be a 1.0Volt output 500A power supply (yes they exist!), being shorted out with your wedding ring.  You would not get shocked, however as your ring heats up due to the short, you will not be too happy.  As a final note, you are the ultimate arbitrator, since you clearly will not get UL approval on your cab.

3) "Grounding" is often misunderstood.   You can only become shocked if there is a voltage across your body.  Your feet would normally be at ground because, well, they're on the ground!   If you connect the (-) terminal to a piece of metal on your desk, you have not "grounded" anything, because the metal needs to be connected to ground, which is the 3rd wire in the power cord.   If you follow this wire back to your electrical panel, out your house, you will find it connected to a metal rod driven into....the ground!   So if you have a metal frame in your cab, unless you have grounded it to the 3rd wire in the power cord, it is not grounded, and connecting the (-) terminal of any power supply will not do much of anything (in fact, it is probably less safe).  In the event the power supply has a short circuit from the line voltage (110V) to an ungrounded output (5V etc), most everything that is connected to the output would be vaporized, and if you happen to be touching anything conductive connected to it, you would be exposed to shock.  If you GROUND the output (5V etc), when the line voltage shorts to the output, a fuse or circuit breaker will trip somewhere and there will be no shock hazard because that output will never get above ground potential due to the ground connection (but there is a pretty good chance your mobo would still be vaporized  ).

That done and said, every cab I have build or can recall seeing has no exposed metal to the user, so I have never 'grounded' any outputs of my cab PS.   Since the user cannot 'touch' anything connected to the power supply, there is no shock hazard.  BTW exposure to shock from 110V to output shorts needs to consider anything CONNECTED to the power supply (i.e. if you had a metal shelled USB key or KB, it could be a shock hazard if plugged to a faulty supply).

Long post, too much idle time this AM.

[markronz]

Wow!  Thanks so much for the response.   I don't even have any follow up questions, thats how good you are!   I am just lighting maybe 20 LEDs, so I should be no where near 20A.

Thanks again!
 

[BadMouth]

You probably already know these exist, but just in case....
 http://www.radioshack.com/product/index.jsp?productId=2103986
Can't tell from the pic, but the screws are recessed inside fairly tall tubes, so it would hard for anything to contact them.
It will take a little work to make jumpers, but you get out of crimping spade connectors on the ends.
Lot less chance of something causing a short, but like you said, nobody will be throwing metal objects around inside your cab.

[markronz]

Thanks for the suggestion BadMouth.   I sort of have a question about that.  If I were to use the european terminal, like the one you've linked, do I have to use a higher gauge wire for the jumper?  Higher than the gauge wire I'd be using for the individual LEDs?    So I will be using 22AWG wire to connect to the various LEDs. 

1.  Can I use 22 Gauge wire to run from the power supply to the terminal itself?
2.  Can I use 22 Gauge wire to make the jumpers on the one side of the terminal?

Just wanted to make sure.  With X amount of LED's, I wasn't sure if it'd need thicker wire.

Thanks!