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I’m not sure what you mean about measuring 120vac “through” neutral. We measure it “with respect to” neutral. Meaning, one probe of your meter is at the terminal on one side of the bulb, and the other probe is on a known neutral point.
On the other hand, when we place our probes on either side of the bulb, we get no voltage difference – they are at the same potential. Thus, we know that there’s no current flowing, and the bulb is just acting like a wire.
If the open in a circuit is on the “hot” or “line” side of a load, where would you be getting the 120vac from?
Correct – there is an open in the circuit.
That’s part of the answer. The other part is which side of the circuit has the open.
It’s a 120vac circuit, so line is on one side of the load, and neutral is on the other.
We measured 120vac at one side of the bulb. What does this tell us about the location of the open – which side of the circuit is it on?
I’ve been replying to your reset requests, asking you to work with me on some of the questions you missed. I haven’t heard back from you. Have you received those emails from me? (if not, check your spam folder.)
1. If current is flowing through the circuit, then why is the bulb not lit? Why is there no voltage drop across it?
Remember: in a series circuit, current is either flowing or it’s not. It can’t flow in one part and not the other. It can’t flow at different rates within the circuit.
Also, if current flows through a load, work will be done, and a voltage drop will be created.
Does this change your mind about whether or not current is flowing in this circuit?
The bulb and receptacle are fine. We just want you to look at this electrically. Please answer the two questions above. I gave you those to show you how you should be thinking about this.
Did you see my reply here? I was expecting to hear back from you, and work with you to make sure you understood the correct answer.
August 3, 2020 at 5:33 pm in reply to: Refrigeration….Just when you thought it was safe to be here; I’m Baaaaaack..! #19456Haha – it’s great to see someone using their brain on a Saturday night!
I’ll have to get Scott’s input on these… it’s been a crazy Monday… will get back to you!
You’ve got a load (the bulb) that we tell you is “good”, yet is not lighting up. So, no work is being done.
1. What does that tell you about current flow in the circuit?
We also tell you that you do measure 120vac wrt N at one of the terminals. This is a 120vac circuit (L1 – N).
2. What does that tell you about the location of the fault – which side of the circuit?
These are the two questions you should be able to answer, if you think about the basics we’ve taught about current, voltage, and voltage drop.
You got it, with one correction.
Voltage doesn’t “travel”, it is present, or felt. Current is what is moving in a circuit (electron flow). So, the electrons are shunted and do not travel through the main coil.
Voltage drop is created by current flowing through a load.
Note – I’ll have to hide parts of your answer so we don’t just give it away to others. The struggle with this question is a great learning experience!
[answer hidden]
Bingo! That is the correct thinking.What does this mean for the ignitor and booster?
Hi Mike,
If I “Zen” the booster – I get L1 on my left and the main on my right.
On your right, as you are working your way to N, you have two options. Go through the main coil, or go through the closed detector switch.
Why did you choose going through the main coil?
Hi Tim – where do you see that it is said that 4 mega watts is 400,000 watts?
July 30, 2020 at 11:26 am in reply to: Refrigeration….Just when you thought it was safe to be here; I’m Baaaaaack..! #19434Right now Scott is using this, which he got from Home Depot
Klein Tools NCVT-4IR Voltage Tester, Non-Contact Volt Tester Pen with Infrared Thermometer for AC Voltage, IR Temperature, Great HVAC Tester
Hi Ronny,
Which part of the video are you referring to? (About what time in the video?)
I know he uses water as an example to explain some thermodynamic properties, but obviously we don’t use water as a refrigerant.
Hi Tim,
Did you see the explanation for Question 3? (it shows up in the quiz results after you take the quiz)
The only appliance on the diagram that uses 240 vac is the dryer. Looking at the dryer schematic and following the line from the common on the door switch, you’ll see that the line goes to a tie point. At the tie point, Neutral and Ground are shown tied together. Since Neutral and Ground are not separated, there are only three conductors needed here: L1, L2, and Ground/Neutral. If Neutral and Ground were not shown tied together, then a four-wire power cord would be needed for the extra conductor.
The drawing shows that ground and neutral are spliced together.
For question 9, by saying that the washer “lost neutral”, we mean for you to assume the problem happened somewhere in the washer circuitry.
Here’s the explanation from the quiz:
The schematic shows that the washer gets its Neutral from the dryer. The dryer gets its Neutral directly from the power cord terminal block. So if the washer lost Neutral, this would have no effect on the dryer. How could the washer lose Neutral? The molex connector that supplies Line and Neutral to the washer from the dryer could go bad, a wire could retract, etc. It happens!
Let me know if you have any other questions.
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