Different ways to wire oven elements

[Britt_Askew]

Thinking of making another oven soon and want to better understand the pros and cons of the different ways to wire oven elements.
Meaning you can use one element , cheaper ? simple ?
or a couple elements in parallel , if one element breaks you should still have one that is working?
or a couple elements in series. My main question is about in series - what would you have if you wired 2 3000w elements together in series ? what are the benefits?
Any pros/cons? thoughts?

 

[Hubert S.]

If you wire two elements in series, you double the resistance and halve the power (P = V^2/R). The only benefit I can see is that the elements will probably last longer.

Generally, I think you want the thickest wire possible for longevity. Thicker wires have lower resistance, so you need a longer coil. I would start by figuring out how much power you want and then calculating the required wire lengths for different gauges and see what you can fit in the space available. If you have not seen it already, there is a good bit of information, including a coil calculator spreadsheet, on Dan Comeau's website.

 

[Britt_Askew]

That is a good site to calculate elements , I have looked at it and can figure out what size/length elements I need I think. When I built my first oven I went by a build here on BF but now all the drawings and pictures are missing and the place I bought my elements no longer sells elements it looks like.
So I am debating wither to just use one element or 2 in series like the oven I am using now for my new oven build. My current oven is .44 cubic feet and the elements are wired in series. From my measurements my old elements are 16ga and somewhere between 3000-3500watts So that would mean my oven is putting out @1500-1750watts? correct. Never timed it but it will get up to 1500 in about 30 minutes.

 

[Backyard]

So far all of mine have been single coil for simplicity but I'm thinking about going with a 240 volt with a neutral tapped into the center of the coil. That way I can turn one off and control tempering temps better. And I can quickly rewire it to 2x 120 volt lines if needed

But like mentioned above, thickest wire you can within the limits of your resistance calculation. I try an calculate the current to be no more then 80% of the breakers rating to prevent it tripping from long use. I try and make it draw as much as practical for faster heating or higher temps and then use a controller to limit the heating as needed

Coils wired in parallel will draw more current (number of coils x coil current = total amps). Coils wired in series will drop the current (coil amps ÷ number of coils = total amps) of course this assumes the voltage is the same. Two coils in series operating at double the voltage will still draw the same amps as one coils rating. Look up ohms law to see how this works regarding resistance and voltage to get current.

In the end, there is no "better" way to wire them up. It really all depends on what you are wanting to do and how complicated you want the controller to be and features you need

 

[Britt_Askew]

The chart on Dans website has an option for 2 elements - that info is for wiring parallel , correct?

Backyard I want to keep it as simple as possible. Simple pid , I just use 1 ssr and no door switch, no lights (the pid has a light that comes on), I unplug the oven before opening the door and plug it back up when the door closes.

 

[Hubert S.]

I believe Dan's spreadsheet assumes wiring in parallel, but it has been a while since I looked at it.

Instead of cutting the power to the elements with a door switch, you could simply have a switch that cuts off the signal to the SSR. That is cheap and easy to do, I can't see a good reason not to do it.

If you use 220V, I would recommend two SSRs instead of just one. Otherwise, there will always be 110V to ground on the element.

I wound my own element from Kanthal using a little jig I built. It was really easy and came out great. Mine is pretty small and runs on 110V. I guess I kept it pretty simple, now I wish I'd made it a little bit bigger. When the coil burns out, I might build a bigger one, but hopefully that won't be anytime soon.

 

[scott kozub]

I did a single element on with 2 ssrs and it worked out well. I had originally wanted to do 2 parallel elements but due to the added length required it was going to be a pain to fit all the wire in the oven so I went single wire.

 

[Stacy E. Apelt - Bladesmith]

I'll just toss out the engineering plusses and minuses.

PLUS - A single coils is simple and easy. Two ends to connect and simple math to calculate gauge/length/stretch. Basic tried and true method. Pretty much foolproof.
MINUS - When a single element burns out, the whole oven goes dead and the whole element has to be replaced.
More difficult to install, especially when covering sides and top.
Tends to lift from channels easier.

PLUS - Multiple elements wired/connected in series can be made easier than one long element.
When one burns out the others are still fine, and only the one element needs replacing.
You can inexpensively wind a few spares when making the original (or order spares if purchasing the elements).
Rather simple build, and operates just like a single element.
Allows for easier placement elements on sides and top.
Stays in place better.
MINUS - More work to make and a bit more difficult in calculation and connections in the build. The whole oven still shuts down when an ele,]ment burns out.

PLUS - Multiple elements wired/connected in parallel have the same simplicity in making as above, but when one burns out the rest are still heating. In many cases the controller merely adjusts the ON time and the oven continues on its programmed schedule.
You should occasionally check the elements while powered to make sure they are all burning.
Allows for elements on any surface but the floor.
You can inexpensively wind a few spares when making the original (or order spares if purchasing the elements).
Stays in place better.
Allows for custom control of what areas are being heated. Even multiple controllers are possible. This would be nice for tempering and for long blade HT situations.
This is the most complex, but the most professional method.
MINUSES - More complex to calculate and wire. Many more connections to make.