Why did electrician use this wire?
 

10 years ago I had an electrician wire in a silk screen oven. The oven was right next to the fuse box so they just took the wiring from the HVAC system and ran it down to a box a few feet from the breakers. Then ran this wire in metal conduit that ran up to a box mounted on the oven frame and then some flexible conduit to the control box.

They used this 1/4 inch thick twisted wire. Why did they use this vs. solid wire?

The powder coating oven I'm building is about 20 feet away from this box on the wall. I thought the easiest thing to do would be to buy or make an extension cord between the two.

Thoughts?

Box as the electrician wired it from the fuse box
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Control box
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Control box with wires from the box and a ground
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Close up of wiring I pulled out of the metal conduit
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Wiring
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Box on wall now. Breaker is turned off of course. I plan on putting an outlet here and one on the side of the control box that will be mounted to the oven and I can run a ground to the oven.
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Nothing wrong with stranded wire. It's more flexible and easier to pull through conduit.

OK, good to know, thanks. Now I just have to figure out how to wire in the outlets.

you have 220 or 3 phase? We can help if you show pic of the wire at breaker, or comfotable measuring voltages. Also, there is a size on wire, a number after the letters AWG

Look on the bright side Shaun. When working with electrical you usually know right away if you've screwed up!

J/K, Green wire (even the black wrapped with green tape )is ground), white neutral and red and black are your 110v hots. C'mon, give it a shot! :D

^^^Listen to Craig. What's the worst that could happen?

When I wired a 30 amp circuit, the home center only had 10 gauge in stranded. Probably because of the pulling issue; solid could be a bear.

thanks, I'm pretty sure this is 3 phase. I can check at lunch. wire size too.

I changed a main breaker on the outside of the building without having the power turned off so I'm pretty comfortable measuring voltages. :D

220, 221 .... whatever it takes.

If I'm not mistaken stranded wire of same gauge carries same current at lesser resistance................

You shouldn't have anything running off the same breaker as your HVAC. That's against code. You could trip the breaker and lose heat in the winter...

Make sure that's ok. Perhaps I misunderstood.

No The wire gauge specifies the cross sectional area.

Stranded wire is more flexible than solid and won't work harden and break in a flexible conduit.

HVAC is completely disconnected. Only the silk screen dryer ran off this breaker for 10 years. I repurposed the heating elements and controller from the dryer to the oven.

Voltage Readings

G-R = 121

G-B = 121

G-W = .X

R-B = 211

W-R = 121

W-B = 121

Shaun:
Is this an office building or a home?
Three phase is ultra unusual in a home. About the only place you can find it 'homestyle' is on a farm.

Office Tadd. Have about 4000 sqft of space.

That is a normal 240 volt supply.

240 between phases (R-B)

120 from each phase to neutral (R-W and B-W)

0 volts between neutral and ground (W-G).

So the outlet would be wired like this. Clearly green is grounded to the box. White is T2. I'll have to double check but I think T1 is black and T3 is red but it probably doesn't matter.

Is that correct?

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Single phase.
Likely the controls run off of one 120v leg thus the white neutral wire, the elements themselves run 220v and use the red/black and green (ground) wire.
Looks like 10 or 8 gauge wire, you might be able to read numbers on the wires.
what size is the breaker?

Wire is 4 gauge. Breaker is 100 amp.

Hoping to have it wired up and working over the weekend though I still have to figure out where to put the thermostat probe. Then I can skin the inside and get some work done.

Here in Northern Europe, it is more or less standard.

We have 3-phase 220/380V 50Hz lead our house main fuse board. It is rather convenient gauge-wise. Main phase fuses are currently 20A but I gather we could go down to 16A as I never busted main fuses despite welders, geothermal heat pump etc. (part of subscription price is based on fuse size).

Those US wire gauges look gigantic to me.

100 amps :eek: I bet that will make your service meter spin. :D

I wish it was 3 phase here, better system and 3 phase is more economical. All North America residential is single phase 60 Hz 120/240V.
As said 3 phase is mostly commercial only and then you have a transformer to run any single phase equipment and lighting.

You can find really cheap used car lifts here, but they're no good to the hobbyist because they're 3-phase.

With 100 amps and #4, you can make it a subpanel. Wire is all there, neutral, Ground, and 2 hot legs.

Then branch off to oven and have room for a few expansion.

How much current will the oven draw max?

Huh? Do you really need a transformer to get single-phase from 3-phase in US?

Not here. All houses are fed by 3-phase. But light loads (TV, fridge lights etc.) are all single phase. You can easily get single phase from 3-phase by connecting the load between one of the phases and NULL. There is no transformer involved.

So you basically connect three groups of single phase 220V loads (which you try to spread evenly across the phases) or you can connect one 3-phase load (in either Y or D-connection).

You can't just tap one leg here because our single phase equipment is mostly 120v, but actually stepping down isn't a big deal and would be part of any commercial service.
As said we never see 3-phase in residential unless it's something like a big farm.

Our residential service has two single phase 120V legs, we get 220/240V by using the two legs in tandem.

Here, the phases are 120 degree apart. So tapping one leg towards NULL gives you 220V. Connecting a load between two phases (without involving NULL) gives you 380V. Makes mixing 3-phase and 1-phase loads rather easy...
Of course, touching two phases will give you rather good jolt, compared to 110V-

I'm not sure I understand this. What do you mean by subpanel? Branch off?

No idea on how much current. There are 3 mercury switches inside, presumably 1 for each heating element in the original dryer. I am only using 2 of the elements. Says 120V with a 35 amp draw.

Running the dryer back in the day, all day, the 100 amp breaker never tripped. Until I needed to replace the breaker on the outside of the building anyway. But internal never did.

I was planning on making an extension cord with this wire I've had laying around. Need about 20 feet, 30 at the most. It's solid core but should be easy to just leave in the room when not in use. It's 4 wires: R, B, W and copper ground.

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First off I always recommend using a licensed electrician for commercial work. There are National Code and also Town Codes that need to be met. Ugly's Electrical Reference is a very handy book for quick reference to code requirements. There are rules that need to be met for hook ups, wet or dry locations, disconnect means, etc.
Most wiring is done with stranded wire, and above certain gauge all wire is stranded.
100 amp circuit should have #2 awg. #4 awg is too small for that breaker. You don't seem sure what amperage you need. The 30 amp outlet shown in post 8 should not be used if 35 amps is required, plus it should not be connected to a 100 amp breaker, breaker needs to be downsized at the least due to wire gauge. Outlet used must match breaker and wire size. 30 ft extension cord would not be legal to hook up equipment.
I would recommend checking the plate on the equipment you are hooking up to see what the rated power requirements are. It will list voltage and amperage minimum requirements. Just hooking up to an existing circuit without knowing your actual need is not a good idea.
For those that desire it in a residential single phase home, 3 phase equipment can be used with a convertor. I have hooked up rotary convertor in a friends house so he could run a 3 phase milling machine in his garage.
As to the sub panel, another panel can be fed from the main panel to allow additional breakers for more branch circuits if needed, but must also be hooked up according to local Code.

I agree, is there not a label on the machine telling you the requirements?

12/ wire is a bad idea as it's is only good to 20amps and that wire would be totally illegal as an extension cord. I also wondered about the #4 wire on 100 amps, I believe code here is 3/

IIRC If you want 40amp on an extension cord you'll need 8/4 SOOW wire with the correct connectors (50amp). Even then I'd run conduit to an overhead box and using a strain relief (Kellem grip) hang it over the approximate location of the oven. This way the extension cord is never laying on the floor.
This is how I did my TIG welder except it's 50amp with 6/4 wire

But as always I'm not an electrician, so I recommend you seek the advice of a pro.

Hi Ed,

The #4 was installed by a licensed electrician 10 years ago. Cost about $1500 to run wire from the breaker to the box shown and then #4 was spliced from the box to the control box of the dryer.

I can run the same #4 or #2 if required, to a similar box in the oven room.

In post 28, there are 3 of those contactors in the control box, one for each heating element. I seem to recall the electrician said they added up to 105 but the 100 amp breaker was fine. Like I said, it never tripped running all three heating elements all day long. I am only running 2 heating elements so I can put in a 70 amp breaker if that will work.

There is no plate on the equipment unfortunately.

here is a pic of what the dryer looked like. Heating elements above the conveyor belt. Control box mounted to frame, you can see the curved conduit that held the 4 #4 wires.



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Good to know. There are generator extension cords I can look into as well.

Because you don't know the true requirements of this unit, I strongly suggest you talk to a licenced electrician.
Sucks, but it's not worth burning your house down.

well a licensed electrician installed this 10 years ago. easy to duplicate 20 feet away.

I gotta go with Sully...

This whole project begins with known current draw for each piece of equipment and putting each on it's own circuit. If we don't know this, please back away from wiring anything. 100A and #4 wire are a clue that this stuff draws a LOT of juice and you want it done exactly right. Not a good DIY money saving project IMO because you will let the smoke out of #12 wire in short order.

May I direct you the thread title.

Yep, I saw it and it frightens me a bit. I love stranded wire. I've done a lot of electrical work and job #1 is matching wire size to the max current draw of the machinery. Don't know that for certain? Stop all work and find out.

This also frightens me a bit:

"I was planning on making an extension cord with this wire I've had laying around. Need about 20 feet, 30 at the most. It's solid core but should be easy to just leave in the room when not in use. It's 4 wires: R, B, W and copper ground."

... with a pic of 12/3 Romex. If you wire that machinery up be sure to have hot dogs and marshmellows handy. It is going to get very exciting for a while.

That's why I post here! With the help of everyone here I wired in a buck-boost transformer a year and a half ago for my compressor and no fires yet.

My protocol is to post here and get great information, help and support. I also google a lot. So by time I actually do something, I'm an expert with 30 years experience. :D

I'm a little confused. I assumed you are decommissioning the silkscreen oven and installing the powdercoat oven?

Sorry, that pic is 8 years old. Yes, the silk screen dryer is no more. The heating elements and controller have been repurposed into the powder coat oven.

The pic with the temp gun below, I just connected the element terminals to a 110V outlet.


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