I have a device that needs a standard outlet connection. The device itself just has the three wires (gnd, neut, hot), but not the actual male end. For now, I’m just using a scrap extension cord which I’ve severed and spliced onto the device’s wiring - alligator clips with duct tape around them.
This is fine for on my workbench, but ultimately, the device needs to be permanent (well, the connection) and portable.
So what’s the best way to make a permanent connection? I’m thinking mar connectors and the whole thing in a small plastic project box?
Just don’t forget the strain relief. You have to make sure that yanking on the cord doesn’t cause the connections to come undone which can cause shorts and other unpleasantness.
Can’t you just get something like this from Home Depot?
That’s just a replacement male plug, suitable (I imagine) for connection to a wide variety of wires. Want to extend it, buy some wire too, and replace the existing wire with the appropriate length with a new plug on the end.
Its very simple. I have a device that needs to be plugged into an outlet. However, it doesn’t have a power cable on it, just three wires. Ergo, I took a regular extension cord, cut the female end off and spliced the extension cord with the device.
The problem with all the suggestions is that it assumes the devices has a regular power cord, just not the male end. It does not. It has three individual wires running out of it. And its an epoxy block so I can’t get inside (its a power supply unit).
An electrical engineer will probably come along and explain it better, but make sure there is no physical strain on the connection. As a teenager when I used to take things apart to see how they worked (well, I still do today!) the power cord most often was either knotted inside the device or clamped to the device so no tension was placed on the actual electrical connection.
So? What do you think a “regular” power cord is? The fix is the same, regardless. If the wires are long enough, attach a male plug directly to them. If they aren’t attach a length of suitable gauge grounded line cord with a male end using either wire nuts or crimp-on insulated butt connectors.
I think Cheesesteak’s solution is best. You can purchase male plugs for retrofitting into power cables. You just strip the ends of each conductor, stick the cable into the plug, and tighten down some screws.
Personally, I like the Hubbell plugs. They’re a little more expensive than the run-of-the-mill plugs, but they’re excellent quality. Try this link. If it works, look at the pics of the plugs in the upper left-hand corner:
Which is precisely what I suggested in my OP, with the additional step of putting the splice in a small box of some sort.
Perhaps my question wasn’t overly clear. I know how to do this. What I wanted to know more or less was if this method is a safe/electrical-code-accepted way.
Well, yes. But sticking three individual conductors into a plug is not considered kosher. They need to be protected in an overall jacket, conduit, or sheath.
A couple ideas come to mind:
Are the wires exiting the appliance through a large (1/2" diameter or so?) hole? If so, you could buy a short, outdoor-rated extension cord, cut off the cord’s receptacle, strip the wires, shove the cable into the hole, and make the connections inside the appliance using wire nuts or whatever. But the cable needs to have a strain relief. This is usually done with a chassis-mount cable clamp.
If #1 is not a good option, I would make a jacket for the three individual conductors using heat shrink tubing. Not 100% kosher, but certainly better than no jacket at all. While you’re at it, use two layers for better protection. If possible, the heat-shrink jacket should extend into the appliance. Then go ahead and stick a plug on it. Afterwards, you should see nothing but heat-shrink tubing between the appliance and plug.
Look, as long as the insulation on the wires is reasonably heavy, there shouldn’t be any problem. You must have seen the sort of male plug I’m talking about: with three screw terminals for each conductor? In these, you have to separate the three individual wires of the power cord you’re connecting the plug to anyway, so what’s the difference? If you insist on a sheath or jacket of some sort, shrink tubing is available in a wide variety of sizes and materials.
#1 won’t work since the wires come right out of the epoxy.
I cannot put a plug on the end of the three wires, no way, no how. Insulation issues aside - the wires are just too short. It must be spliced to an extension cord.
So, here is what I propose: Get a plastic project box. In one end goes the three loose wires, with a sheath around them. This can be knotted. In the other end goes the sliced extension cord, again knotted. The wires are then appropriately connected.
Is the power supply by any chance for the HeNe laser you asked about in this thread? If so, I’m assuming that you’re talking about “flying leads” that are only a few inches long, so attaching a male plug directly is going to require an extension cord anyway, unless you like everything really cramped.
I’d say go with the project box idea. Mar connectors (if they’re what I think they are) would work, but a more reliable setup would be to nibble or file a hole in the box for a standard three-pin IEC connector. Attach the flying leads from the power supply either by soldering (using heatshrink tubing for the professional look) or crimping to spade terminals. You can also add a switch in series on the “live” lead (assuming that you ever want to turn your laser off!). Then you can just use a standard power cord to connect to the wall outlet. This method solves the strain relief problem, makes everything professional-looking, and takes up less space wherever you end up storing it when not needed, since you can use the power cord for other devices.
BTW, did you get the HeNe laser (linked to above) working? I’m assuming so. Are you getting a nice intense beam?
It’ll work, although, IMO, it’s a bit of overkill. But hey, if you really want to go for the gusto, you can then fill the box with something like epoxy or silicone RTV.
99% of commercial power cords confine the individual wires inside a common jacket over the exposed portion. This is for two reasons: a) To offer more protection to the wires, and b) to bundle the individual wires. The only commercial power cords I’ve seen that do not confine the individual wires inside a common jacket are the heavy-gage, 3-condutor cords like you see on some microwave ovens. I’m sure you’ve seen them… three conductors molded in a row.
Anyway, it would appear there’s some new information now. Or else I haven’t been paying attention, which is a good possibility :
The wires exit through epoxy.
The wires are very short.
Hmm. If it were me, I guess I would do the following:
Buy a short, outdoor-rated extension cord. The appliance’s maximum steady-state current draw will dictate the wire gage (12 AWG, 14 AWG, 16 AWG, etc.).
Cut off the cord’s receptacle.
Strip back about 3" of the cord’s jacket.
Strip about ½" of insulation off each conductor.
Slip a piece of heat shrink tubing over each conductor. Each piece should be about 1" long or so.
Slip a large piece of heat shrink tubing over the cord’s outer jacket. This piece should be about 6" or 7" long.
With the heat shrink tubing kept as far away as possible from the solder joints, solder the appropriate wires together (hot to hot, neutral to neutral, gnd to gnd.)
Slip the smaller pieces of heat shrink tubing over their respective solder joints, and shrink with a hot air gun or match.
Slip the large piece of heat shrink tubing over the entire mess. (Hopefully, this piece of heat shrink tubing will be able to cover everything up – including the individual wires coming out of the appliance. In other words, one end of the heat shrink tubing should butt right up to the appliance.)
Shrink the big piece of heat shrink tubing with a hot air gun or match.
There are small details I’ve left out. But if you’ve done this type of stuff before, I’m sure you’ll be able to figure it out.
I like Antonius Block’s solution even better, and that’s what I’ll go for.
And yes, I am indeed referring to a HeNe power supply I managed to dig up. I actually found a bigger laser tube amongst my collection - 12" or so long. It produces a very nice beam and is most deffinitely more powerful than 1mw
Yep, that’s the sort I’m talking about. It’s mechanically no different than three separate insulated conductors. The NEC might gripe about wiring a plug onto separate conductors, but it’s silly, IMO. In any case, I, too, like ** Antonius Block**'s solution too. It appeals to the engineer in me.
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