TEST

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rawvie

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1 = If the function/range switch is set at 200 VAC, what will the multimeter read if a measurement is made directly across both terminal of a good fuse or circuit breaker in a 120 VAC line ?

Would it be =(0 VAC) = (120 VAC ) (200 VAC)

2 = If the function/range switch is set at 200 VAC, what will the multimeter read if a measurement is made directly across both terminal of a Blown fuse or tripped circuit breaker in a 120 VAC line

Would it be =(0 VAC) = (120 VAC ) (200 VAC)
 
Re: TEST

I'll give you a hint: 0 volts appears across a short, and the full circuit voltage appears across an open, assuming there is only one open in the circuit.

Now your challenge is to figure out which is a short and which is an open in your example. We can't simply give you the answer; you have to make some attempt to understand the problem.
 
Re: TEST

One more thing. Do you know what reading you get if you de-energize the ckt. and check it with a continuity tester?
 
Re: TEST

Hi Peter so the answer would be 0 VAC ??????????

I wish i could understand english as good as french
thanks anyway
rawvie
 
Re: TEST

Hi again where i'm confuse it when they say ACROSS BOTH TERMINAL OF A ....if the breaker is in line how can you measur it from both terminal


before i got confuse whit this Across BOTH !!!!!
i would say
1= is 120 VAC
2= is 0 VAC
but now cause of that both are 0 VAC
can you see how mis up i'm
 
Re: TEST

Think about the function of a fuse/breaker. What does it do? What's the difference (physically) between a fuse that is functioning and one that has blown?

These questions are easier than you think if you actually have a multimeter.
 
Re: TEST

Hi again where i'am confuse it when they say ACROSS BOTH TERMINAL OF A ....if the breaker is in line how can you measure it from both terminal


before i got confuse whit this Across BOTH !!!!!
my answer was
1= is 120 VAC
2= is 0 VAC
but now cause of thati think both are 0 VAC
can you see how mis up i'm
 
Re: TEST

A fuse or breaker has two terminals: one to connect to the source and one to connect to the wiring it's protecting. You already know that the source is 120V, so the questions ask what the voltage will be on the other side.

If the fuse/breaker is working, would you expect to see voltage or not? Does a fuse/breaker consume voltage or increase it?

If the fuse/breaker is not working, would you expect to see voltage on the other terminal?
 
Re: TEST

If you have a multimeter, take a good fuse and a bad fuse and check the continuity across the terminals. You can do the same thing with a circuit breaker by moving the switch between open and closed.

If you know the continuity, you know what the resistance is. What does voltage do when it goes through something that has zero (or nearly zero) resistance? What does voltage do when it tries to go through something that has infinite resistance?

The reason no one is just giving you the answers is that this is fundamentally important stuff, and if you plan on working in the electrical field, it's critical that you understand this material.

[ October 01, 2005, 10:26 PM: Message edited by: jeff43222 ]
 
Re: TEST

rawvie,
This is the third time you have posted the same question. First, you got the correct answer the first time you posted the question, and second we do not permit the same question to be posted in multiple places.

You need to think about what I asked the first time that you posted this question. "What voltage would you read if you connected your meter between two points on the same conductor?" Then apply that information to question #1.
Don
 
Re: TEST

Rawvie, here's a not-so subtle hint:

Q. What does a voltmeter sense?

A. Difference in potential ("voltage").

Now you must stop and think about if there will be a difference in potential between the red test lead of the meter, and the black test lead of the meter, for the two scenarios you have given us.

That's what Don is talking about:
You need to think about what I asked the first time that you posted this question. "What voltage would you read if you connected your meter between two points on the same conductor?"
Click to expand...
This is a very important question for you to answer, Rawvie. What would this reading be?
 
Re: TEST

Would it help clear things up if you thought about a switch for a light?

If the switch is in the on position and you measure across the switch by putting your test leads on the screws that hold the hot and switched wires to the switch, what would you read (assume the lamp and circuit are good)?

If you turned the switch off, what would you read?
 
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