Do you have a clamp on ammeter? Can you measure the current draw of heater?

12 gauge wire is only good for 20A, and should not be used with 100A breaker.

True.
The wire should match the size of the breaker unless additional fusing/overloads/breakers are utilized.

I like Shawn's project. It makes me wish that I could better utilize my spare time....

I don't have one but can get one.

Klein Tools 400 Amp AC Auto-Ranging Digital Clamp Meter with Temp-CL210 - The Home Depot

Quick google search says I need 3-3-3-5 SER cable for 100A. Why the licensed electrician used 4, I can't say. I'll have to check what they used for the 208 outlet 50 feet away from the fuse box, I think that one is 60A.

At a little over $6/foot, I'll do all new wiring from the fuse box to the room.


Here's a question. When I tested each heating element, I just connected 12 gauge wire from a standard wall outlet to the terminals. Took some time but each element got up to 600F. I only need 250F or 300F at the most.

The mercury contactors are only 35A each. Are they a bottleneck? But more importantly, the wiring inside the control panel, specifically the wires at T1, T2 and T3 receiving current from the 4 gauge wires. Why are they not all fried? And the braided lines in the pic below, those run to the heating elements. Why are they not all fried?

What does that tell you about the electrical requirements for this system?

Couldn't I use a much lower fuse box breaker to send less current to the system with the only drawback being longer time to heat up?

http://forums.pelicanparts.com/uploa...1487426266.JPG

"Quick google search says I need 3-3-3-5 SER cable for 100A." You cannot do this.

From what I can see from your previous voltage readings, you are using a 2 pole single phase circuit with a neutral and ground. Is the current breaker a 2 pole or 3 pole 100 amp? As to the original electricians opinion that 100 amps was needed, I think he was way off.
You cannot use romex as a cord, it can only be run in walls or ceiling, not exposed. You really need to either run cable inside the wall, or emt conduit externally to the oven, with a disconnect switch by the oven, and then a short flexible conduit to the equipment. The wire needs to be rated and fused for the needed load.
I suggest you try and do a search of the equipment you are re-purposing to find the manufacturers original power requirements. This would at least give some help figuring out what is needed.

Shaun,

Each one of those 4 gauge wires is feeding thinner wires, but there are 3 thinnner wires on each post so those would add up to a pretty fat wire too.

Appears that individually each heating element draws a lower amperage, but as a system the draw is much higher.

Rutager

Changing the fuse or breaker will not reduce the current demand, it will trip if the heaters try to draw too much current.

Current = Voltage/Resistance

If you want to lower current, lower voltage (connect to 110 instead of 220) or increase resistance by putting heaters in series instead of parallel.

Internal wiring is often smaller, and may not make sense, but the fuse/breaker is to protect the wire not the appliance. Same as plugging a light wired with 18 gauge lamp cord(or smaller) as opposed to the 12 or 14 used on the circuit.

As the wire is smaller, I suspect the heaters draw less current. That's why I suggested measuring.

I don't suppose there is a rating/specs on the element itself? The heating element is likely resistive wire, can you isolate and measure the resistance?

I'll get the clamp on later today/tonight.

Quick test across the element connectors, one measures 15 and the other 30 ohms. But both connectors are very dirty and I want to dremel each with a mini flap sanding head to get accurate readings. Unfortunately the entire day I have to polish a set of 68 window frames to bring to Canada on Tuesday/Wednesday.

I may still have the manual for the dryer, I'll look for it. I think the company is still in business and can also contact them. The elements have nothing on them.

Looking quickly online, these are probably 3000+ watt elements.

Replacement Screen Printing Conveyor Dryer Elements (Infrared)

Another consideration is that the silk screen drier was sold as a manufactured and approved unit or system. Manufacturers can in some cases utilize smaller wire size internally on packaged equipment.

When it has been disassembled and re-purposed it is not the original configuration you will most likely need to abide by local code.

At work there is some large demonstrators (for refrigeration) that utilize what has already been suggested above. The main power comes directly into a small breaker panel that protects each of the individual circuits with an appropriate overload rating.

http://www.chromalox.com/catalog/resources/technical-information/electrical-wiring-theory-wiring-practices.pdf

P=V^2 / R 220v, 15 Ohms = 3200 watts, so that makes sense.

15 Ohms, 220V, (I=V/R) each element would draw about 220/15 = 15 amps.

And yes, for the purists out there, no need to debate, I'm making admitted assumptions. But the order of magnitude is the same.....

Bottom line, 100 Amp service wire/breaker seems both silly and dangerous.

Wish I was closer, I'd grab some tools and shoot over.

If you buy a meter, think about a DC & AC clamp.... it will come in handy for the car also! (great for checking alternator or looking for parasitic battery drain)

That would be cool, it would be great to meet! Some other time.

Bought a Klein CL210.

12 gauge wire connecting terminals to 110 outlet.

15 ohm element reads 9+ amps

30 ohm element reads 4.8 amps

Found the ancient manual. Here are the original specs:

230V, phase 1 service
10.8 Kilowatts
56 amps

This is for 3 of the heating elements, I am only using two with resistance as noted.

With all of this information, should I downgrade the breaker to 60A in the fuse box and then run wire to the room?

60 amp breaker should be ok then. Current will approximately double at 220v vs 110. The 12 gauge wire is only good for 20 amps. Not sure what gauge you need for commercial & distance.

Are you using the original controls?

Good to know. I'll get some 6/4 then and run that, will save a bundle on wire cost.

Yes, I'm using the original controls. I wired in a new digital temp controller to the original 30 year old analog dial wiring and it worked well. Just need a longer probe lead to manage temp.

Thanks for the help!

Do you have a 60A breaker you can try? I suspect it will be fine.

Don't rework the elements to use 110V instead of 220V, that would give you 1/4 of the power, and it will be useless....

I have a 60A breaker for the compressor, that's the outlet I wired a buck-boost tranformer alongside to get 240V.

But simple enough to put another 60A in and then run the wiring to the room.

Here's the wiring for the HVAC on the roof. This was originally connect to the 100A breaker until the electrician ran the silk screen dryer to that breaker. The HVAC has never worked (I've been here 11 years) so I'm going to use this wiring for the oven. It's already in place and actually goes to the oven room. It is plastic sheath like the 2 gauge wiring coming from the outside breaker. The electrician used metal sheathed wire when installing both the dryer wiring and the 208V socket in the darkroom for the exposure unit.

Took wire pics upside down.

Above the fuse box. Large metal sheath is the dryer.
http://forums.pelicanparts.com/uploa...1488934593.JPG


First part of text on wiring
http://forums.pelicanparts.com/uploa...1488934593.JPG

Second
http://forums.pelicanparts.com/uploa...1488934593.JPG

Third
http://forums.pelicanparts.com/uploa...1488934593.JPG

More importantly, how do I find the short in this circuit?

http://forums.pelicanparts.com/uploa...1488951458.JPG

Shaun, that's an aluminum cable. OK to use, but needs aluminum rated connections, and I believe a special anti-corrosion creme.

You shouldn't 'wire-nut' connect it to copper wires.

OK, thanks, that's what I thought on the cable type and good to know what I can/can't do.

I was going to connect each stand directly to the box. Not sure what they are made of but will look later today.


http://forums.pelicanparts.com/uploa...1488987181.jpg

Thought I would be able to test it out today but, no.

Got some Noalox at the hardware store, hooked it, was very happy about there being no sparks and 120V between T1-T2 and T3-T2 and 210V between T1 and T3.

Put the heat gun on the thermocouple probe and the temp controller relay clicked at 210F. I didn't connect the leads to the heating elements, need to get new wire (length) but I did measure the voltage and they were oddly 61V, 54V and 45V. Called the silk screen dryer company and they said I should have 120V for each one.

So I started testing the internals quickly found that the mercury contactors are not working correctly.

From left to right in the pic below:
All three, white to top black are all 120V

Black bottom to black top are
61, 54, 45

I'm puzzled. Also puzzled about the wiring going to the heating elements. It's cloth covered then 3 layers of very thin mylar-like plastic "fiberglass" and then the silver stranded wire, looks like 12 gauge.

http://forums.pelicanparts.com/uploa...1489524153.JPG


http://forums.pelicanparts.com/uploa...1489524153.JPG