# EVALUATING YOUR CIRCUIT WITH MULTIPLE HEATER ELEMENTS

Posted by Moonshiner Chuck on

The last one we discuss on a single element, we use the 2000 watt 120-volt element, 240 volts versus 120 volts we only did the one element, and what we realized what we came to find out was that one element or 120 volts operating at 100% power pole 16.6 amps. Normally we're running these on a 20 amp circuit so we are safe and we can run that all day long. Continue to run it is really good because it's on that 12 gauge wire which can handle 25 amps, but it's only a 20 amp circuit.

What happens when we put on multiple elements because we do have some hobbyists that have a little bit larger mass in the need for elements? when you put two elements into it, this is sort of like counterintuitive when you stop and think about it on a 120-volt circuit, or a 20 amp circuit of 120 volts. it's counterintuitive. You think that well if I increase resistance because when resistance goes down, the amperage goes up. But if I increase the resistance that the amperage would come down, that's not necessarily true in a parallel circuit. A Matter of fact, in a parallel circuit, they have a reciprocal relationship. When you plug in the toaster, the iron, the hairdryer, the coffee pot, on your 20 amp circuit, it goes pop. You have to start unplugging things and go back and flip the switch back on. It's counterintuitive, I've increased the resistance on that circuit.

So since my resistance went up, then my amperage should go down. It's actually the reverse when the resistance goes up, the overall resistance added together is lower than the lowest resistance in that circuit. If you had four things hooked up their resistance was 5.5, ohms, 10, ohms, 15, ohms, and 20 ohms. Once you add all those together, because of the reciprocal relationship, the total resistance on that circuit is going to be lower than the five-ohm resistor. It's not like All together and you go we got 510 1520 added together. It's gonna be lower than the five-ohm resistance. Remember when your resistance goes down, your amperage goes up drastically.

In the last topic, we introduced you are the letters we use what we do know and we know that we've got w for wattage or power. We've got D for voltage or a the electric motor force. Got a four amp, amperage then we've got our four resistors. We know that we've got a 2001 heater element at 120 volts.

The voltage squared divided by the wattage equals the resistance. We're just doing a root Quick review. So you can speed through this if you want. We know we've got 120 volts squared divided by 2000 watts,  what is the resistance of that element 120 hit the X two button, that's a on your calculator that equals 1400 and 14,400 because that's 120 times 120 divided by 2000 equals 7.2

equals 7.2 ohms of resistance.

We know we got 7.2 ohms of resistance, but remember what we were looking for. We're looking for amperage because we know we're on a 20 amp circuit, we've got a 25 amp wire or a 28 amp circuits so 20 is our limit. In order to figure out the amperage, we already know this constant, and we also know this one that's supposed to be 120 there is a zero and we already know this value. So we just do this we know that voltage divided by resistance equals our amps. 120 volts divided by 7.2 ohms of resistance equals 16.6 120 divided by 7.2 ohms equals 16.6 amps.

Now it's 16.666667 is leaving 16.6 for an example, we've got this 16.6 amps. If we're going to put two elements on, we're going to have another 16.6 amps. So that's not going to equal 66 twice, not going to equal 42. If you had them on a series circuit, it would, but we're on a parallel circuit.

So remember, there's an inverse relationship. Let's get to that real quick so that we can so we can figure out what this value or what overall resistance is going to be. We're on a 20 amp circuit Remember that? Okay, and as I said, there's an inverse relationship. So we will have put these back up in the A. What we know is that our resistance for 2000 watt heater element, we know that that is 7.2. ohms of resistance, we find out what's the total resistance in that circuit if I have more than one if I add another one to it, It's the inverse relationship.

It's one over 7.2 plus one over 7.2. and these are both ohms equals one over and I'm gonna use a number and then read the reciprocal, which is you divide the bottom then the top gives you your total. I know that sounds confusing. Now in this particular case on almost scientific calculators are we've all got the buttons on your calculators, you probably just don't even know they're there. We'll take 7.2 7.2. on my calculator, it looks like this one x. The one x is, stands for reciprocal. So I hit shift on mine, one x and that equals point 13888888. Then I'll say plus 7.2.

Again, shift one x, because I want the reciprocal, which is another point 1388888888 that that equals point. One would be point 2777777. The reciprocal of that is on your calculator, you push shift that one x but again, that brings us to a total of 3.6

ohms of resistance.

So we've taken two ohm resistors and put them together in the same circuit, when we add them because of their inverse relationship we add them together the total resistance in that circuit is now 3.6 ohms, not 14.4 ohms. It is kind of counterintuitive. Now if we take that 3.6 ohms and then we will find out what remember we're looking for amps. I know that you remember the formula for that is voltage divided by resistance equals amps. So let's do that. We have 120 volts divided by 3.6 ohms 120 divided by 3.6 equals surprise 33.333 amps. We've just busted our limit.

Remember we had a 20 amp circuit and now we've got 33.333333 amps because we've put two 2000 watt heater elements together on that circuit. So we've got to be a little bit more inventive or a genius about this. Now here's a couple of recommendations, we could actually start using this we could use a 3500 watt 240 volt element and wire that 120 volts that would be 875 watts if we had a 5500 element 200 40 volts and we wired it on 120 volts, that would be 1300 and 75 watts. But that doesn't tell us anything unless we do the math. Let's do the math together. All right, now we've got a 20 amp limit.

You can also run this on a 30 amp circuit and kind of avoid all these some of these problems except for that last one we did even on a 30 amp circuit to 2000 watt heater elements, draw 33 amps. Let's try to figure out a way what can we do to make this safe and make this efficient, make this effective so that you can be successful. Alright, we've got a couple of options rolling. We've got WVA are wattage volts amps resistance. We could do the following we have, we could use a 5500 watt 240 volt, put that on 120 volts and that would equal 1300 and 75 watts.

So we got a little bit different to play with because you can't buy a 1300 and 75 watt element. We've also got another option with 3500 watt element, that's 240 volts, we put that on 120 and that's going to equal 875 watts. We can get a 1500 watt element that runs on 120 volts and that's going to be 1500 watts. So what happens if we Marry these up instead of two 2000 watt heater elements. Do we actually need to have the

powerful ones? Or can we use to have a limited power one so that we don't exceed our amperage draw? Well, yes, we can. Were going to do the 5500 and 3500. Because you think that again, intuitively, it's counterintuitive. That'll make a big difference and it does. We've got voltage squared divided by watts equals resistance. And then our voltage divided by resistance will equal our amps.

Let's take that 1300 and 75 watt heater element, we're going to do it on 120 volts

divided by 1375 do to 120 x two x, which equals 14,400 divided by 1375 equals 10.47. So we've got now we've got 10.47 ohms of resistance in that element. If we use the same formula before we get, we've got 120 volts in an 875 watt element. We'll do that math is 120x two which equals four 14,400 again, divided by 875 because that's 875 watts now equals 16.45 16.45 ohms of resistance. That's for that element. We're not even got to the 1500 watt element yet.

Now if we did the 1500 watt element 120 x two equals 14,400, divided by 1500 watts equals 9.6 that goes to the one. So that's the resistance in the circuit for those, remember the formula we used. When we added those together? They're different.

It could because we know we've got again, we've got that 28 threshold. If I take this let's put the two together and the 5500 watt which is now 1375. 3500 watts is now 875 because we've wired them on 120 volts, let's put them together. One, or 10.47 ohms plus one over 16 point, I know four or five, you're getting ahead of me, which is a good thing equals one over a number and we're going to figure that out. That one X key on your button on your calculator looks like one a slash. An X stands for reciprocal, it will divide the bottom number in the top number for you. But it'll divide the number into one for you.

So we'll take 10.47 in all my calculator, it's a shift button to get to that. Shift, one x plus 16.45. and you're probably already hit me again, shift one x equals, in this case it equals point 1563. I'll be put point 156 free. So that's the number we got, we got one over 1.1563. Now, the last step is shift, we want the reciprocal of that. So we want this divided into one. So I shift one x equals 3.97 6.397 equals 6.397. That is the total ohms. In that circuit we added these two together, so we use two, the 10.47 and the 16.45 ohms of resistance, we just figured out that if we put them together in that parallel circuit, remember I told you before it is only as long as your resistance in a parallel circuit the total resistance will always be equal or will always be lesser than that.

The lowest resistance is going to be total of 6.397 ohms of resistance in that circuit. What do you think the amperage because remember, we're looking for what is the amps? What is the AMP draw on that circuit? Remember the formula for that. It's volts divided by resistance equals amps. V divided by r equals a. You're down to the last part of this task. 120 volts divided by 6.397 6.397. You could have probably rounded that off. Equals 18.75 amps. 120. But if I'm starting to run out of paper equals A to pull in seven, five amps, we are under the 20 amp threshold.

So in order to make our system safe, efficient and effective, and to be successful, there is an occasion when if you're going to use multiple elements unless you have the circuit that's available to provide all that power, you've only got a 20 amp circuit, or 155 or 130 500 watt element that are that's designed for 240 is wired at 120 because it reduces to 1375 875. Then we figured out the resistance. Then we figured out what the total resistance was.

And then we figured out what the total amperage was in that system. Now we've got 20 amps available, but we're only required 18.75 amps and that's if both of those elements are operating at 100% See how easy that is? Now you can do the same thing with the 1500. There's so many combinations and I hope that made sense to you. Because at the very end of the day, we want you to be more important than anything more important than being successful. We want you to be safe.