Is it advisable to use a 30 A fuse in circuit that is rated to carry only 20 A?

Answer 1

Yes, 20 amp fuses are available in many different sizes and types.

If what you meant is "Can you upgrade from a 15A to a 20A fuse?" then, for more information, see the answers to the Related questions shown below.

Answer 2

The fuse is supposed to be the weakest link in the circuit. The circuit is rated to handle a specific load current. The wire and insulation rating of the circuit is governed by this specific load. If this load malfunctions and the load current becomes higher that what is specified, the fuse is there to break the circuit. A fuse of a higher rating than what is called for will allow a higher current to flow through the circuit which could cause the insulation on the wire to melt, the wire to burn open or components in the circuit to become unusable. Never over fuse an electrical circuit with a larger amp rated fuse.

Answer 3

Certainly. Providing that the circuit is capable of safely carrying 20A. But the circuit was most likely put on a 15A fuse for a reason. ie. the circuit can't handle more than 15A. As a general rule, always replace a fuse with another of the same rating.

You need to ensure that all wire in the circuit is at least 12 gauge. This is usually not the case in lighting circuits where the wire gauge is typically 14 gauge. Also all switches and outlets on the circuit should be rated 20 A which is non-standard. If you are replacing the 15 with a 20 because the circuit keeps tripping, that is probably a BAD IDEA.

Answer 4

The purpose of a fuse or breaker is to prevent electrical fires. Using a 30 in place of a 20 is not advisable even if it does not immediately cause a short. Taking a chance with that is like playing with your life.

<><><>

Fuses are sized to protect conductors

If the appliances plugged-in or connected to a circuit all used to work ok without blowing the circuit's 20 amps fuse, the first thing you must do is find out if a new fault has developed inside one of the appliances. A fault in an appliance is what needs to be fixed first and then you can repair or replace the blown 20 amp fuse with another 20 amp fuse.

If the 20 amp fuse for a circuit blew because you have just plugged-in a different appliance that had not been used on that circuit before, it must be overloading the circuit and you should either:

• plug the appliance into a separate circuit which can take the load without blowing its fuse or
• re-distribute all the existing loads on the circuit until its 20 amp fuse stops blowing or
• install an additional circuit with the right wire size and fuse or circuit breaker to supply all the required appliance(s) safely.

<><><>

Changing from an existing 20 amp fuse to a 30 amp fuse because the load you are trying to supply makes the 20 amp fuse blow would never be advisable - it is called "over-fusing". Before you ever do that you must be sure that the circuit's wiring is adequately sized for that higher current level.

If there is a 20 amp fuse already, it is probably because the wire is only rated to carry 20 amps. Putting-in a higher fuse size would allow the circuit to be overloaded, with possible conductor damage and fire as a result

House fires often break out because someone has put in a fuse with too high a rating and let it run continuously in an overloaded state. If left like that, it can eventually get hot enough to start a fire.

<><><>

As always, if you are in doubt about what to do, the best advice anyone

should give you is to call a licensed electrician to advise what work

is needed.

Before you do any work yourself,

on electrical circuits, equipment or appliances,

always use a test meter to ensure the circuit is, in fact, de-energized.

IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB

SAFELY AND COMPETENTLY

REFER THIS WORK TO QUALIFIED PROFESSIONALS

Answer 5

In a temporary situation yes but it should be replaced with the correct size as soon as possible.

No, the fuse is meant as protection for the circuit. Installing a larger fuse can cause the wiring to burn if a short occurs.

Answer 6

No, the fuse must be rated lower. If a 30amp fuse is used on a circuit rated as 20amp, the cables would heat in the case of a short, before the fuse would blow and switch off the circuit - leaving a fire hazard.

Answer 7

but it shouldn't. a higher fuse won't warn you of an issue before damage occurs in the circuit.