Physics Question

val101

Hi all

I’m doing an assignment for physics class and its to do with electrics. The question is:

Which one of the following would cause an unsafe situation?

• A 6 amp fuse in a 60 amp circuit
• A 60 amp fuse in a 6 amp circuit
• A 60 amp wire fuse in a 80 amp circuit
• A 6 amp cartridge fuse in a 60 amp wire fuse way

I do not just want the answer but an explanation would be helpful in helping me understand why it is the answer, many thanks.

jerryh3

Before you get the answers, why don't you diagram each situation and look at each in an overload or fault condition. What level class is this?

Stubbie

I have no problem with helping with your assignment but for your learning experience you should tell us which one you think is correct and why. BTW there indeed is one that is unsafe. We can help but lets share a little of the leg work.... with you telling us what your thoughts are about the question.

220/221

Amperage is current FLOW.


A 60 amp circuit will handle 60 amps safely.

The fuse protects the conductor (circuit).

val101

the answer is "b"


The fuse is there to protect the wiring/circuit etc. It is basically a purposefull weakest link which you want to fail before the circuit gets hot, melts, explodes etc.



Never fit a bigger fuse than the circuit is designed for, the fuse is a safety device to protect the circuit.

HandyPete

Hey Newbie...Good reasoning so-far but your answer could be right or wrong depending on some of your terms.

A 6 or 60 "amp fuse" or "fuse cartridge" is in my opinion the correct terminology and will be easily understood by most. However, the terms "amp circuit" and "amp wire fuse" are ambiguous. It doesn't really let us know if your talking about a connected load, a wire size capacity or a circuit depending on the fuse size.

There are three things to keep in mind. Wire Capacity, Fuse Size, Connected load.

Here's what a few conditions "should" sound like..

1) A 6 amp fuse protecting a #6 AWG wire

2) A 60 amp load connected to a 6 amp fuse

3) A #6 AWG wire connected to a 80 amp load protected by a 60 amp fuse

4) A 80 amp fuse protecting a #14 AWG wire connected to a 60 amp load

and so forth, there are a lot of dangerous and safe combinations...

-- pete

__________________
---pete

jrclen

Good job.

Stubbie

Unfortunately this appears to be cut and paste of someones answer to the same question on another forum...... No way to learn....

NateHanson

Yep. http://www.diynot.com/forums/viewtop...1194bb7745826d

jrclen

I'll be darned. I take back the good job comment.

kilroy33

If you have a 60 Amp fuse in a 6 Amp circuit, then there is no protection to that circuit. The fuse will never blow unless a short occurs. If there is no protection then the insulation will be damaged overtime and a fire can occur.

BigJimmy

I agree. Then on the other hand, NAIL might comment which would teach him a lesson! HA!

__________________
The very existence of flamethrowers proves that some time, somewhere, someone said to themselves,"You know, I want to set those people over there on fire, but I'm just not close enough to get the job done." - George Carlin