Conceptual stage: Electrical Questions

[PoorOwner]

New here.. I think I start to understand within a couple hours reading this forum, electrically, I need a contactor which is a basically giant relay right, and a controller, and heating elements?

stealing ideas parts idea from
contactor wiring

I plan on getting a cutler hammer 40amp switch from famousparts
and this same controller from ebay,

http://cgi.ebay.com/Celsius-999C-Dig...QQcmdZViewItem

My question is, nothing has been built yet, I am wiring up a 40-50 receptable for my welder soon, which will share with the future oven. I am not sure if I need to have neutral in my circuit or not, can't I get 240V version of parts?

240V coil contactor is available, the controller is available in 240V. If I want to add a timer to turn off the controller, does not having a neutral restrict my selection of timer?

Or, should I just bite the bullet and wire in a neutral now? It probably makes wiring a fan in the easier as well because of having 110V?

Next question, if I have 240V, 3100W elements x 2, thats 25.8 AMPS, is a 30 AMP breaker safe enough to use? 30 amps x 80% is 24 amps, which is just slightly under guideline.

[JTW37]

Sounds like your on the right track. There is a lot of info here for setting up an oven, I just got mine going. Prior to that I used an old kitchen oven. It was just to small. Don't know how big your making yours, but I made mine with three elements. Others have had a many as 12, others 4 and so on.

I have attached my wiring for my oven. I used a ground, because an electrician told me too. Don't know how much better it is or worse, but I have it.

my wiring I made colored coded, so it would be easier to follow the wires. But I use 120v and 240v with it. The contactor will work with either 120 or 240. As for the controller, mine will work with either one, as well. I have the digital controller, which you can find on Ebay for around $32.00 to $45.00. Mine is pretty elaborate as far as the internals, but more pricey. Glad I didn't have to pay for. my son got it from the electrician where he works.

Anyway, take a look at my wiring and some of the others. Some use three wire and I used four wire (gnd). I tapped into the L1/L2 and Neutral for 120v for lights, fan, controller etc. Either way will work, I guess.

You can take a look at my oven progress if you want. it's located here:
http://s80.photobucket.com/albums/j1...20Coat%20Oven/

Good luck and Have fun!
JT

[PoorOwner]

Thanks for your diagram. It helps. Do you have the same ebay controller. just wondering of the pinouts for your controller.

What size do you recommend for a car hobbyist? I am thinking of building
24"x24"x48". Because that's about the size for the blast cabinet I am building.

That will fit a wheel, I am not baking sub frame or rear ends something like that.

[hbracing]

Nothing wrong with useing a neutral and a ground. the ground you need to save your skin in case of a short. better safe than sorry. Be sure the wire type and size are rated for the job you are trying to do. This is just as important as the contactor size and the breaker size. Ohms Law is a good one to know..................

[JTW37]

My oven is 36"x 36"x 72", but for what you want, yours sounds like a good size. As a matter of fact, I'm building a smaller one (3x3x3) to do smaller items in. Will probably use it more then the big one. As for the controller, mine did not come from ebay. You should get a booklet with it to tell you how to wire it. It should also be on the case of the controller. My next controller may come from ebay.

[gourdhedd]

You need the neutral if you have any 110v accessories. You'll connect one of the legs of the 220v service to one side of the accessory (fan, timer, etc) and the neutral to the other side, which will provide 110v to the accessory. This also makes the neutral(probably a white wire) a current carrying wire and thus unsuitable for a ground. At this point, you'll also need the bare ground wire attached to the frame to provide a low resistance path from the oven back to ground rod in your electrical service. If you don't install this ground wire, the next lowest resistance path to ground may be your body, and if your oven has a short circuit, if the conditions are right, and if you touch the oven when the short circuit occurs, the current will flow through your body to ground, perhaps killing you. Don't underestimate the importance of a ground.

If everything that consumes power in your oven is 220v, you'll only need the two 110v legs of the 220v service and a bare ground, once again attached to the frame as a safety feature to carry stray currents to the ground rod.

Personally, if I were running the circuit new, I'd put in 3 conductor with ground. How much more could it cost, $.30/LF?

[PoorOwner]

Hi, thanks for your suggestion, I do understand the role of ground and neutral. I am questioning whether I can easily build a 220V only system: 2 wires + 1 ground. The reason is that I am going to share the oven with my welder with the same plug, and the welder doesn't call for neutral. The problem is not the cost at all, I want a clean install that will work for both the welder and the oven.

Is it very hard to find a externally mounted motor @ 220V for the fan? Maybe a small blade or propeller at the end of the shaft..

The controller and contactor is available at 220V, and I probably won't have a window therefore no light, so the fan is probably the last piece of electronics that I know of right now.

[gourdhedd]

Originally Posted by PoorOwner

Is it very hard to find a externally mounted motor @ 220V for the fan? Maybe a small blade or propeller at the end of the shaft..

The trick will be to find this find this fan. The first place to look would be in convection ovens. The Jenn-aires, Kitchen Aids, etc all have circulating fans, though I'm not sure if they are 220v. If you want, I can give you the model number of such an oven and you can do a search through internet appliance parts suppliers. Failing that, look at Grainger, McMaster-Carr, MSC Direct or Burden Surplus Sales for an aftermarket unit.

[hbracing]

useing the oven and the welder is no problem and a good idea to keep things clean and universal like you said. Configure for the oven and only use what you need for the welder. Same plug You just do not use the neutral. As far as the 220volt fan, ditch that idea and go with 110 volt. Options are far greater. Look further into the forum and you will see guys are useing induction fans off of furnaces, and again this is my choice. Cutler Hammer brands can be pricey you can even go to your local electrical whole sale house and get a guy who is willing to help. If he shares your intrest he will more than happy to help. Good luck...............

[PoorOwner]

Should I weld everything together or not?

I plan to put angle iron on 4 corners and add sheet metal on the sides.

similar, offseted construction for outside to hold insulation. I might use fasterner and rivet for the outside since i might not want to weld after putting the insulation in there.