Combination Circuit Question School

[Strathead]

This kind of question really bothers me "... How would you accomplish this task? Explain your answer."
So I've lost count on how many ways that have been mentioned so far. Even though they are all different, they correctly answer the question: "... How would YOU ..."

Now either the question is designed to make the students think about how it might be accomplished (which would be great), or the instructor is really asking "... How would I accomplish this task? Explain you answer." (which kinda stinks)

Now for MY answer. If they want lights now, the next thing they'll want is 120V receptacles. Put in a mini-power zone and wire the place up right, with a light outside at the door, and outdoor receptacles, too.

I think you are getting to the same answer as I a, basically one of two. First answer, "I wouldn't." Second answer. Install a transformer to generate a neutral, with all the other code requirements that come along with that. Well there is a third answer, flashlights.

 

[Joethemechanic]

The premise is that the room in question only has the 240V circuit. No information on whether this is center-grounded like we do in the US, or end-grounded like 220V thru 240V circuits are in most of the world.

Yeah, we don't know if this is the USA or some weird place like England where they eat faggots and peas

 

[ggunn]

No information on whether this is center-grounded like we do in the US, or end-grounded like 220V thru 240V circuits are in most of the world.

It wouldn't make any difference to a two wire 240V supply with no neutral.

It never ceases to amaze me how we can go down a rabbit hole of electrical design over a simple test question meant to teach a newbie about series - parallel circuits, but I guess it's what we do.

 

[ActionDave]

You can hook up 120V lights in series and power it up with 240V. It's no more complicated than that. Some scraps of wire and some wire nuts and you are the bringer of light to a dark world. What could be better?

You don't need to buy resistors. You don't need to go to another country. You don't need to hook up a diode. You don't need a transformer. You don't need a multi volt fixture.

The question is a good question. It's good way to introduce theory in an introductory class. That's all it is. Good lord, it's not aimed at the maintenance crew being deployed on the International Space Station.

 

[Little Bill]

The question was not "how should this be accomplished", it was "how would you accomplish this."
It just sounds like they want the students to think how they would accomplish it and explain their thoughts.
The way the question was posed, the writers were just trying to get the students to learn, which may not be just one solution to the task.

No mention of series, or parallel, circuits, no mention of whether there was a neutral in the building, no mention of whether the lighting should be 120V fixtures, or 240V fixtures. I see it as just a way to get them to think, then maybe they would discuss the different ideas proposed. So, no single answer. If a single answer was required, I think it would have been multiple choice.

 

[ggunn]

... no mention of whether there was a neutral in the building...

From the OP: The power supplied to the boiler is 240V single-phase without a neutral conductor, and The lamps are to be connected to the present 240V service inside the building. It does not explicitly say that there is no neutral in the building, but...

 

[Little Bill]

From the OP: The power supplied to the boiler is 240V single-phase without a neutral conductor, and The lamps are to be connected to the present 240V service inside the building. It does not explicitly say that there is no neutral in the building, but...

It doesn't say the building service had no neutral, just that the boiler was supplied with 240V and no neutral. The boiler really had no impact on the question. IMO, it was just something that could throw you off. A lot of test questions are that way. They throw in stuff that doesn't need to be there.

 

[ggunn]

It doesn't say the building service had no neutral, just that the boiler was supplied with 240V and no neutral. The boiler really had no impact on the question. IMO, it was just something that could throw you off. A lot of test questions are that way. They throw in stuff that doesn't need to be there.

Test question: Little Johnny has three apples. His friend Jane gives him two apples. How many apples does Johnny have now?

Our response: What kind of apples are they? If Jane's apples are half the size of Johnny's, how many apples does Johnny really have? Are all of Jane's apples in edible condition? If one or both of them are unripe or rotten do they really add to Johnny's apple total? Is Jane actually there in person to give him the apples or does she tell him over the phone that they are now his? How trustworthy is Jane? Do we know for sure that she even has two apples to give to Johnny?

 

[Strathead]

Test question: Little Johnny has three apples. His friend Jane gives him two apples. How many apples does Johnny have now?

Our response: What kind of apples are they? If Jane's apples are half the size of Johnny's, how many apples does Johnny really have? Are all of Jane's apples in edible condition? If one or both of them are unripe or rotten do they really add to Johnny's apple total? Is Jane actually there in person to give him the apples or does she tell him over the phone that they are now his? How trustworthy is Jane? Do we know for sure that she even has two apples to give to Johnny?

I think you missed the obvious question. When did Jane give him 2 apples? I guess you could also ask whether Johnny has eaten any apples.

 

[Little Bill]

Test question: Little Johnny has three apples. His friend Jane gives him two apples. How many apples does Johnny have now?

Our response: What kind of apples are they? If Jane's apples are half the size of Johnny's, how many apples does Johnny really have? Are all of Jane's apples in edible condition? If one or both of them are unripe or rotten do they really add to Johnny's apple total? Is Jane actually there in person to give him the apples or does she tell him over the phone that they are now his? How trustworthy is Jane? Do we know for sure that she even has two apples to give to Johnny?

I think you missed the obvious question. When did Jane give him 2 apples? I guess you could also ask whether Johnny has eaten any apples.

Correct answer is Johnny and Jane got married. Then they got divorced and Jane took all of Johnny's apples!