Ratings of Fuses for household applications?

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Discussion Overview

The discussion revolves around the ratings and applications of conventional rewirable fuses, miniature circuit breakers (MCBs), and polyfuses (resettable fuses or PPTC fuses) in household electrical systems. Participants explore whether polyfuses can replace traditional fuses in high-power applications and discuss their limitations and appropriate use cases.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • Participants inquire about the ratings of conventional fuses and MCBs, as well as polyfuses, particularly in high-power applications.
  • Some participants express skepticism about the feasibility of replacing conventional fuses with polyfuses, questioning their suitability for household applications.
  • One participant clarifies that MCB stands for miniature circuit breaker.
  • Concerns are raised regarding the limitations of polyfuses, particularly their inability to disconnect the circuit in the event of overcurrent, which is deemed a critical safety issue.
  • It is noted that polyfuses may only protect electronic circuits under certain conditions, specifically if the overcurrent is of short duration.
  • Another participant emphasizes that fuses and breakers are primarily designed to protect users and building wiring, rather than the connected electronic circuits.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether polyfuses can effectively replace conventional fuses in household applications, with multiple competing views on their safety and functionality.

Contextual Notes

Participants mention regulatory requirements for disconnection devices in electrical systems, highlighting the importance of safety in electrical installations. Limitations regarding the operational characteristics of polyfuses are also discussed, particularly in relation to their response to overcurrent conditions.

jobinhere
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What is the rating of conventional rewirable fuse, MCB etc.

What is the rating of polyfuse(resettable fuse or PPTC fuse). Polyfuse are normally used in electronic circuits.

Can we replace conventional household power supply main rewirable fuse with these polyfuse. Is it available in such high power requirement?

Pls help.
 
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jobinhere said:
What is the rating of conventional rewirable fuse, MCB etc.

What is the rating of polyfuse(resettable fuse or PPTC fuse). Polyfuse are normally used in electronic circuits.

Can we replace conventional household power supply main rewirable fuse with these polyfuse. Is it available in such high power requirement?

Pls help.

Welcome to the PF.

What's an MCB?

In general, I don't think you can replace a real fuse with a polyfuse. What is your application?
 
MCB = miniature circuit breaker.
 
Then, In which all places, we can use a polyfuse.

What are its limitations?

Why can't we replace a conventional rewirable fuse/MCB in electric circuits in our home by a Polyfuse?
 
Hello jobinhere what is your normal working discipline?
Is English your first language?

Any competent electrical engineer or electrician would tell you that the correct term for what is popularly called a household fuse is actually a 'disconnection device'.

The important part here is the word disconnection.

The regulations in most countries require a device which actually disconnects the attached equipment from the electricity supply in the event of overcurrent.

Polyfuses (again a popular misnomer) may not be used because they do not disconnect the apparatus.

This is an extremely important safety matter which should not be taken lightly.
 
jobinhere said:
Then, In which all places, we can use a polyfuse.

What are its limitations?

The polyfuse only increases in resistance when it is overloaded. When it cools down, the resistance returns to its regular low value.

So it is useful for protecting some electronic circuits from overcurrent conditions, but only if the short-circuit condition that caused the overcurrent is of short duration. If the short circuit fault condition is permanent, the polyfuse will eventually fail...

http://en.wikipedia.org/wiki/Resettable_fuse

.
 
So it is useful for protecting some electronic circuits from overcurrent conditions

A fuse or breaker is there to protect the user and the building (wiring), not the connected electronic circuit.
 

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