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: 23.06.2025 12:21
This is the picture of an electronic coil of wire wound around a core of magnetic material.
so, what happens?
When the current is 200% of the rated value , it will “go open” (the link metal melts) and protect the device.
There are two important concepts here.
The other is “what does a “fuse” do?”
It’s been three xxx five werks, and there has been no response to my follow on query on his Commment to my answer.
In schematic diagrams this is the symbol for a fuse:
There are three different concepts here that are getting confused.
These are simplified answers to the original question, and does not change anything I wrote above.
An AC voltage/ current source, and an ac inductive load.
This is where the MOV conducts again, and dissipated the energy.
These devices are installed between the “hot” and “neutral” and protective ground.
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The bolt then partially travels down the line to your home.
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?
The third is lightning and “how it gets conducted into a home.”
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2024–10–10[John johnson John Johnson ]
Upvotes:
but I think this circuit , shows a few more pieces.
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[old diagram got deleted by accident]
2024–10–16 [ OO OLAOYE OYEBODE ]
A fuse is a non-resetable over current circuit protector.
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One is “what exactly is in a ‘surge protector’ ? ”
The MOV will conduct when the voltage exceeds 50% of line voltage.
But it can get overloaded, and no longer works.
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OK, this is Mohan Rajaratnam’s definition of a Surge suppressor.
2024–10–14 [Omar Gharbi Omar Gharbi ]
2024–10–11 [Victor Olarewsju Victor Olarewaju ]
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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.
2024–10–00 [ Ammar Mahdi ] Ammar Mahdi
Now when you have a certain ac resistance, then a current flows in a loop.
but this device (an Inductor) … impedes the rapid changes in the current.
Can the fuse protect the electronic devices from lightning instead of a surge protector.
Because the load is inductive, the current lags the voltage.(by a bit).
This is 'the assistant's answer'
“ A fuse is a device which protects the (circuit) against overload and short circuit.”
Barnstars:
Mohan forgets that a fuse is a one-time device, and needs to be replaced if it is tripped.
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.
I post the exact comment here.
What is lightning?
This one hit behind the barn.
It seems Mohan does not understand the difference between a comment and an Answer.
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.
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what exactly is a ‘surge’ protector?
Would individual surge supressors have save this equipment? most likely, since the surge supressor would take the jolt instead of the electronic components.
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.
What does a fuse do?
First Sentence:
And this is the problem alone. Is the power supply in the equipmemt designed with a lightning strike in mind? Some yes, others, no.
At one ohm, the resistor has a maximum of 1 watt power.
(There is no concept of polarity, in the loop because the current changes direction 100 to 120 times a second (power frequency).
So combined with a device called a MOV or Metal-oxide-resistor, then forms the 3rd part of a “surge suppressor “.
If the nominal power is 4,000 watts then the current at 230volts is 16 amps.
[image of Common-mode choke]
He then asserts :
So, the voltage could go up to 500 volts, and the fuse will not open up.
P = e* I, so since I is 16 amps, then the voltage dropped is 1/16 volt or 0.0650 volts.
This is where this question deviates from being a 'generic' question, and becomes more specific.
a photo is worth a thousand words.
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.
But… the neutral is now “floating” because of the 1 ohm resistance.
This device then solves the entire problem.
2024–10–11 [Bobby Sanchez Bobby Sanchez ].
so, the loop of wire then, when put together with another loop reduces the ‘noise’ on a power line.
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.
But during the surge, the fuse will not blow if it is a longer duration and lower value )10 to 50%).
At least they know the answer if they wanted it.
He then describes the function of a fuse.
A circuit breaker is similar, but is resettable.
the problem then depends on "how fast does the fuse operate?".
So, it’s possible that these devices from Trip Lite have addition suppression devices, these ones seem to be sturdy.
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(Dc diagram shown, AC is similar).
Here is a simplified AC power diagram.
For this case there are devices called Metal oxide varistors (MOV).
Edit 2024–10.
Fuses, on their own, then operate much slower than the MOV variable resistance, during the lightning strike.
It also is a device that limits the change in current flow.
“ 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”
“ … to protect building, lightning arrestor, is provided above building and directly connected to earth.”
He then describes Rainy Season and Lightning.
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.
Is the question then , "why buy a surge supressor, if the fuse alone protects the electronic circuits from a lightning bolt?".