I saw a few things in this thread, which I just discovered, and thought I'd put my 2 cents in. I'm a former electrician, but I was never fully licensed by the state, so take this with a grain of salt. I used to work mostly with 3-phase 277/480Y and 120/208Y systems in commercial & industrial settings, so I know a little bit about high voltage wiring. I am no expert, however, so keep that in mind when reading the following.
numbertalk wrote:Another question - what gauge wire did you use to connect the AC inlet/mains power to the primary side of the power supply transformer? Would it be ok for me to use stranded hook up 24 AWG wire, for example? Should I use something heavier on this side of the power supply?
I would use either stranded or solid 12 gauge wire designated as "THHN
" wire, the kind you’ll find at Home Depot for wiring the electrical in your house and most commercial installations. It should be rated for 600 V, as well. The thicker the wire, the less resistance. Less resistance equals less likelihood of the wire burning up.
That said, 14 gauge should be the absolute minimum you'll want to use for wiring on the mains side. While you're only drawing a few amps on the output side of your PSU, remember that the breaker in your panel is usually going to be a 15 A or a 20 A breaker. In case your electrical system actually delivers that much current to your PSU on the mains side, you'll want to size your wire high enough to accommodate that inrush of current an not fail (i.e. melt the insulation). This is why I would use 12 gauge, which is rated up to 30 A.
If you shop at a place like Home Depot, you should be able to buy it by the foot, which should only set you back a couple bucks. I work part time at a True Value, and we sell 12-14 gauge wire for 25 cents/foot. It’s not terribly expensive. It's only when you buy 500+ ft spools of 10-12 gauge wire that it can get up there in price.
The wire I'm going to use to go from the AC inlet to the power supply is this stuff from Maplin.
Its max. current is 6A and its nom. conductor area is 0.75mm2
. According to a chart, 0.75mm2
equates to halfway between 18 AWG and 19 AWG - do you think this is thick enough?
I’d recommend 14 gauge as a minimum. I am going to wire my PSU up with 12 gauge if not 10, which I happen to have a ton of around the house from rewiring my house (mostly the kitchen) a couple years ago. If anyone is ever passing thru Madison and happens to need a bit for your DIY project, hit me up. I have a couple 500 foot spools of 12 gauge left over. LOL
bf wrote:Odd note, but when I wired the studio I did so with the receptacles having the ground up (I know this is contrary the the typical practice). If a power cable was ever partially pulled out and something were to fall and make contact with the plug, I'd rather it hit the ground prong than the hot one. I don't understand why the common practice is the other way around.
It's more common than you might realize. National Electric Code has no opinion on how outlets are installed, so you can feel free to install them however you wish. However, some builders have spec'ed installing a certain way, like when building a new office building, a hotel, etc. The electricians have to follow what's in the spec book, per the designer or customer.
Kopter wrote:Another pretty noobish question: I'm about to start wiring up my Power-One supply, and I'm wondering which kind of wire to use. I mean, would using 18 gauge be OK for both my mains
No, use 14 gauge as a minimum. 18 will probably work, but should there be a fault in the line, you'll want some overkill by having thicker wire. Go with 12 gauge if you can, and you shouldn’t ever have to worry about the wire heating up/melting.
BBlack wrote:Can you tell me how necessary 600V wire is? The wire I'm using doesn't have a voltage rating...
EDIT: Nevermind, found some. But one thing - is it the wire that connects to the transformer's terminals that needs to be 600v, or all the wire involved?
It's probably a really good idea to use 600 V wire for the mains wiring, yes, and it's best to use the thickest wire you can use. For the low voltage outputs to your distribution points, you certainly can use the same 600 V wire. You'll have a substantial amount of voltage & ampacity "headroom" in that wire.
ndkent wrote:Not an expert but can probably help. U.S. voltage should be 110 to 120v.
120 V +/- 10 V (110-130 V) isn't unheard of for a range of voltages you'll see in typical single phase residential wiring. There are differences in 3-phase systems, when looking at 208 V vs 230 V, but those are mostly power issues that will be found in commercial settings, and won't really matter to most users.
NOTE ON GROUNDING: Use as big of a ground wire as you can, which will help reduce resistance to earth. The less resistance you have on the ground, the less likelihood of having noise problems. Graham Hinton can definitely school all of us on this topic, and his advice should definitely be heeded.
Also, it's part of the NEC (National Electric Code) that ground wiring and terminal screws should be colored green, and should have appropriate insulation. I know few will adhere to this, but for insurance purposes (should anything ever blow up), adjusters can and will look for anything they can to deny a claim. Not having your system wired & grounded to code can be quite costly, so splurge for the green wire and green grounding screws in the electrical department.