What exactly is the difference between a surge protector and a fuse? Can a fuse protect the electronic devices from lightning instead of surge protector?
Last Updated: 21.06.2025 00:38

This is 'the assistant's answer'
Now when you have a certain ac resistance, then a current flows in a loop.
At the secondary, it is 1000 times less.)turns ratio). If it gets hit with a 100,000 volt bolt of lightning then the voltage arrestors conduct and clamp the voltage down to line voltage, ( but a small amount leaks down the line). This is the problem.
(There is no concept of polarity, in the loop because the current changes direction 100 to 120 times a second (power frequency).
At one ohm, the resistor has a maximum of 1 watt power.
In schematic diagrams this is the symbol for a fuse:
So, it’s possible that these devices from Trip Lite have addition suppression devices, these ones seem to be sturdy.
2024–10–16 [ OO OLAOYE OYEBODE ]
P = e* I, so since I is 16 amps, then the voltage dropped is 1/16 volt or 0.0650 volts.
This is the picture of an electronic coil of wire wound around a core of magnetic material.
This is where the MOV conducts again, and dissipated the energy.
It’s been three xxx five werks, and there has been no response to my follow on query on his Commment to my answer.
For this case there are devices called Metal oxide varistors (MOV).
What is lightning?
So, the voltage could go up to 500 volts, and the fuse will not open up.
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These devices are installed between the “hot” and “neutral” and protective ground.
These are simplified answers to the original question, and does not change anything I wrote above.
It seems Mohan does not understand the difference between a comment and an Answer.
I post the exact comment here.
Fuses, on their own, then operate much slower than the MOV variable resistance, during the lightning strike.
“ A surge suppressor is the one which is connected at the input supply so that when there is a sudden change voltage it bypasses thereby protecting the (circuit) and electronic components”
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Upvotes:
This is a high voltage low current spike that comes down the line because of the power poles being struck, and the voltage suppressors activating on the primary side of the transformer.
This is a photo where a lightning bolt took out a home's complete mains distribution box, and a lot of electronic gear as well.
“ … to protect building, lightning arrestor, is provided above building and directly connected to earth.”
At least they know the answer if they wanted it.
But during the surge, the fuse will not blow if it is a longer duration and lower value )10 to 50%).
There are two important concepts here.
Mohan forgets that a fuse is a one-time device, and needs to be replaced if it is tripped.
Here is a simplified AC power diagram.
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This device then solves the entire problem.
He then describes Rainy Season and Lightning.
The third is lightning and “how it gets conducted into a home.”
2024–10–11 [Bobby Sanchez Bobby Sanchez ].
This is an electronic circuit designed to clamp voltages so that the Voltage Potential that appears at the outlet is never going to exceed the nominal value.
The bolt then partially travels down the line to your home.
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so, what happens?
2024–10–10[John johnson John Johnson ]
If the nominal power is 4,000 watts then the current at 230volts is 16 amps.
Barnstars:
A circuit breaker is similar, but is resettable.
so, the loop of wire then, when put together with another loop reduces the ‘noise’ on a power line.
OK, this is Mohan Rajaratnam’s definition of a Surge suppressor.
The MOV will conduct when the voltage exceeds 50% of line voltage.
(Dc diagram shown, AC is similar).
One is “what exactly is in a ‘surge protector’ ? ”
Edit 2024–10.
2024–10–11 [Victor Olarewsju Victor Olarewaju ]
This one hit behind the barn.
There are three different concepts here that are getting confused.
Lightning arrestor is a spark-gap device, and can be installed anywhere. What is important, is that the wire is thick enough to withstand the lightning bolt and conduct the energy away from the building.
There is no harm in having the surge suppressor along with the fuse in the circuit. The fuse will not open up until the current melts the link. This will take time, and in the interim, that jolt will get transmitted into the power supplies.
When the current is 200% of the rated value , it will “go open” (the link metal melts) and protect the device.
the problem then depends on "how fast does the fuse operate?".
A fuse is a non-resetable over current circuit protector.
2024–10–14 [Omar Gharbi Omar Gharbi ]
Once the voltage goes over 0.0650 volts, then this fact can be used to amplify the difference, and turn the circuit breaker off , furthur down the line. Essentially that is what a RCD/GFCI does, it compares the incoming current, to the outgoing current, and if the difference between the two currents is over 5mA, then it trips the circuit breaker.
2024–10–00 [ Ammar Mahdi ] Ammar Mahdi
An AC voltage/ current source, and an ac inductive load.
Would individual surge supressors have save this equipment? most likely, since the surge supressor would take the jolt instead of the electronic components.
what exactly is a ‘surge’ protector?
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But it can get overloaded, and no longer works.
Can the fuse protect the electronic devices from lightning instead of a surge protector.
He then asserts :
It also is a device that limits the change in current flow.
2024–09–27 [ Mohan Rajaratnam Mohan Rajaratnam ] . Thinks you can get free electricity from nothing : Mohan Rajaratnam's answer to Is it possible to generate free electricity at home using a magnet or other low-cost methods? If so, how does it work?
So combined with a device called a MOV or Metal-oxide-resistor, then forms the 3rd part of a “surge suppressor “.
Because the load is inductive, the current lags the voltage.(by a bit).
Is the question then , "why buy a surge supressor, if the fuse alone protects the electronic circuits from a lightning bolt?".
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[old diagram got deleted by accident]
And this is the problem alone. Is the power supply in the equipmemt designed with a lightning strike in mind? Some yes, others, no.
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but this device (an Inductor) … impedes the rapid changes in the current.
First Sentence:
but I think this circuit , shows a few more pieces.
But… the neutral is now “floating” because of the 1 ohm resistance.
a photo is worth a thousand words.
He then describes the function of a fuse.
This is where this question deviates from being a 'generic' question, and becomes more specific.
The other is “what does a “fuse” do?”
What does a fuse do?
“ A fuse is a device which protects the (circuit) against overload and short circuit.”
[image of Common-mode choke]