Electrical Assistance Please - Wiring up UV Exposure Unit

[polyglot]

Of course you can disregard any warnings and you'll probably survive. I don't have anything to say about dichromate because I'm not a chemist; as far as I'm concerned you're welcome to drink it

As to people hacking on stuff - I've seen so much horrifically dangerous DIY wiring that I stand by my warning whether you believe it or not. A good percentage might survive but there are a hell of a lot that didn't, including people who were not involved in the DIY efforts.

I say this as someone who reckons people should do more experimentation and DIY stuff, and especially they should hack on things they own. However, mains power is fickle stuff that can get to places that you really did not expect it to unless you know exactly what's going on. I'm not saying you should never ever work with the stuff, just that some electrical & electronic education is in order first, i.e. an understanding of basic circuits and exactly how grounding works as a safety feature, as a minimum. You also need to think of the mechanical failure modes (what happens when dropped, bumped, snagged on something; whether any parts like cords are subject to wear) of what you're building, how that might create electrical hazards and how to mitigate those in the construction. Please at least make sure you have proper strain-relief on the supply cord and that all internal cords are covered by a rigid case and therefore not subject to snagging.

 

[holmburgers]

I will do my best to make it safe polyglot.

I'm planning to use cord "brackets" or whatever you call the collars that go around cables and allow you to secure them to the base. Ultimately, this thing is only gonna be plugged in for exposures and only when I'm present of course.

 

[cramej]

Simple, really

Re: Dowel legs - holmburgers

It's likely you'll have to make those - really easy, though. Find appropriate sized dowels and get wood screw threaded studs and tee nut inserts like the attached. Wood screw threads go in the dowel, 1/4"/20 threads go in the insert that you put in the light base.



Edit: Also helps when I read the rest of the thread and see that the general idea has already been tossed around.....

 

[holmburgers]

Thanks carmej,

Actually, I think I've found an even simpler solution. You can get these plates and screw in these legs (available in many different lengths).

 

[holmburgers]

Howdy everyone,

I finished wiring this all up last night and well, I didn't burn the house down! I just need to get the legs, put some curtains around the sides and start exposing.

I'll post some pictures once it's all said and done.

Thanks for everyone's help; I needed it, and I'm pretty pleased with the result so far.

 

[BrianShaw]

Good for you! I'm looking forward to your pictrues.

 

[holmburgers]

Version 1.0 - UV Exposure Unit with CFL Black Lights

Ok, here she is.

It's not pretty and not completely done yet; still need to get 5 more bulbs and then make a curtain to go around the sides, but I suspect it should work well!

As you can tell, the wiring is somewhat of a hazard. One ill placed set of fingers and ZAP, 120V right to the kisser. I need to figure out a way to hide the wiring.

I've already got ideas for v2.0. Thinner MDF, or solid wood, lamp "cleats" that don't require any kind of drilling thru the board & also facilitate wiring on the front side, plus legs that angle outward.

I found front-wiring sockets after the fact, realized that 3/4" MDF is too heavy and my hardware store only had straight leg-plates. They do make leg plates that will splay them out slightly, and I think that it would be better to avoid reflections from the legs and being a little closer to the contact frame might not be a bad idea either. But all told, the unit packs up into quite a small package.

Anyways, gotta live with this one for awhile, unless someone wants to buy this one so I can get to work on the next one! Sorry for the slightly dark photos.

 

[Curt]

For code and safety make sure the socket is wired correctly; The hot wire connected to the hot terminal or black and the neutral or white to the neutral terminal.

That way the therminal end of the bulb, the soldered end tip is hot, black and the aluminum shell of the bulb is neutral or white.

The reason is if someone should put their hand on the bulb and come into contact with the shell of the bulb they won't get shocked or killed.

This is true if all house wiring too.

Get an appliance electrical cord with the plug already attached at lowes or hd.

 

[holmburgers]

Thanks Curt, that's the kind of thing I would've never thought of.

However I fear this particular unit will never be up to code... something to strive for in the next version.

 

[mark]

That is some scary wiring there. 4 1 inch strips of MDF and another "table top" will hide the wires and keep wondering hands off. Never underestimate the stupidity of guests.

 

[holmburgers]

I agree mark, I really do. It'll never be plugged in unless I"m using it, and the toggle switch will provide one (tenuous) layer of protection.

Luckily it's just me and the GF living in my apt., and she knows about the danger.

 

[mark]

You, your girl friend, the romantic BL glow filling the room. That's what memories are made of.

 

[polyglot]

holy shitburgers, that's extremely dangerous. This is why I was suggesting that doing it would be a bad idea and this is way worse than even I was expecting.
- your wiring is completely exposed and on BOTH sides of the board!
- your wire gauge is completely inadequate (it needs to be 1mm^2; that stuff is a fire hazard)
- your wire is not multi-stranded (safety issue with it fracturing, fire/arcing hazard)
- your input cord has no strain-relief (one trip will yank it out, leaving bare ends)
- there is no ground (ungrounded systems are suitable ONLY when double-insulated, this isn't even insulated at all!)
- half your wires go under the wrong sides of the screws (tightening the screw pushes the wire out)
- you have the sockets on the wrong side of the board (those are face-mount ones) which is why the wiring is exposed

You need to at least build a box over the back of that thing and move the switch to the other side of the box so that all the wiring is on the inside. And take the cord off it right now until the thing is completely enclosed. What you should really do:

- move the sockets so they don't go through the board, only the wiring does
- use stranded lamp cord for the wiring (like you have on your brown cord)
- crimp and solder ring-lugs on each end of each wire, then screw the rings to the terminals
- cover the wiring on the back with some plywood or masonite
- mount the switch facing out
- tie a figure-eight knot in the cord where it goes through its panel hole so that the mechanical load is not on the electrical connections.

terrifying stuff.

 

[fotch]

Polyglot is rigtht, do not use as is.

 

[bdial]

That wiring is scary thin.

I'm with Polyglot and Fotch, I wouldn't remotely consider using that thing as it sits.

Polyglot's suggestions are not "icing on the cake", but fundamental, like focusing before you release the shutter.

 

[holmburgers]

I am thankful to have so many people looking out for me...

Ok, ok, I thought solid wire was good for the inside connections, and stranded to the mains. There is some protection from yanking the cord, with the cable harnesses, no?

Obviously I can't defend my build much, because I don't know much (re: anything) about electric wiring, which you guys have so effectively pointed out. Hey, can we chalk it up to a learning experience?

Please tell me the gauge of wire for wiring the interior connections.

Since I'm the one on this side of the situation, it's easy for me to see some humor in this, particularly from polygot here... "holy shitburgers"... probably the first time I've seen that on APUG.

I can only imagine what this looks like to you guys though; knowing what you know about electricity and not knowing much about me.

Hmmm, holmburgers hasn't logged on lately..., what was his real name?, check the Lawrence obituaries...

But you know, despite what I might be giving you as supporting evidence, I am not a complete fool. Obviously I'm ignorant about this field of knowledge, but give me the benefit of the doubt in terms of assuming I'm not going to go tripping over my cords, that this thing will be plugged in and operating for sporadic & brief, heavily supervised periods of time (I'll be in the middle of carbon printing; a fairly focused activity) and that we're not running a daycare in my apartment.

However, I can't say I deserve any other reaction! To see a build like this and for it to NOT illicit cautionary remarks would mean that something is wrong with the forum; that people have stopped worrying about others. That's what makes APUG special, and I appreciate the straight talk.

Rest assured, steps will be taken to make it safer, if not an outright rebuild.

Am I free to leave?

 

[BrianShaw]

Please tell me the gauge of wire for wiring the interior connections.

I'm waiting for the experts to explain (or say I'm mistaken) but my house, as are most in North America to the best of my knowledge, wired with 14 gauge solid wire.

To be honest, I noticed that the sockets were attached in an unorthodox manner and the wiring seems more like a series circuit... but maybe just a cover over the exposed wiring would make it safe enough for "experimental use" as it is intended to be used. If this was intended to be a commercial consumer product I'd say "holey sheet" is a reasonable reaction, but it isn't.

 

[holmburgers]

I think it's in parallel; at least, it works with any number of bulbs from 1 to 7.

I think that that is 14 gauge solid wire; when I picked it I remember that it fit the specs I had been told.. sooo....

Yes, the mounting of the porcelain bases is unorthodox and was a last minute change. In terms of where the bulbs sit, this worked out much better.

 

[BrianShaw]

I think it's in parallel; at least, it works with any number of bulbs from 1 to 7.

I could have my "series" and parallel" mixed up. My electrical engineering and electrical contracting consultant (i.e. dad) died a few years ago and I'm still a bit lost. If it works with one bulb missing or burned out then that's probably what's really important... no matter what its called.

 

[BrianShaw]

p.s. This might be an unpopular opinion... but I'd use your contraption!

 

[holmburgers]

thanks Brian

I guess if we just call it a "working prototype" it doesn't have to be safe!

 

[Steve Smith]

This might be an unpopular opinion... but I'd use your contraption!

So would I!


Steve.

 

[mark]

Are those home depot bulbs or did you order them from somewhere?

 

[holmburgers]

Well I will be using Feit brand CFL blacklights, which yep, I get at Home Depot. Lowe's seems to have different brands, but I figured I should keep it consistent for now.

The porcelain bases are also from HD, though what I should've used were front-wiring sockets that I later found at Ace Hardware.

 

[mark]

Thanks