How many joules is your surge protector rated for?
That's an important question!
What's a joule? Does that have anything to do with the family joules?
In a way yes, but it has nothing to do with the family jewels.
What is a joule? A joule describes the amount of work needed to derive a given unit of heat or energy, and is a part of the International System of Units.
It is named for English physicist James Prescott Joule (1818-1889) and defines what it takes to pass a current of one ampere through a resistance of one ohm for one second.
There, wasn't that easy?
A joule helps to define a watt: it is the work required to produce one watt for one second.
And to define a volt: it is the work required to pass an electric charge of one coulomb through an electrical potential difference of one volt.
You might have a surge protector that looks a lot like this.
What you want to know is if your the surge protector you spent money on will protect your stuff from a power surge.
THAT is where the joule comes in!
If your house or system experiences a power surge (voltage spike) is your "whatever" protected?
What a surge protector does is try to limit the amount of voltage supplied to an electrical device during some sort of voltage spike. It does so by blocking it, or trying to dissipate it by sending it to ground (a short). Theoretically they can protect against even a lightning strike.
Note: sometimes people confuse a power strip with a surge protector and a strip provides no surge protection.
Surge protection has to do with clamping voltage (also called let-through voltage ) and THAT has to do with all the protective components inside the surge protector that divert the unwanted energy.
The joules rating of the surge protector has to do with how much energy the MOV-based surge protector can theoretically absorb. What? MOV means metal-oxide varistor which are components that essentially divert electrical current into a particular direction.
The typical surge protector is built using MOVs. A lower joule number in the MOV-based surge protector indicates that the detector is able to absorb less energy. The better protectors can exceed a peak rating of 1000 joules. Trying to absorb a surge larger than it can protect can cause MOV-based protectors to catch on fire.
However, one of the surge protector's jobs is to send energy to ground and even a low-joule-rated protector can send 30 joules to ground for every joule it can absorb. A surge lasts microseconds, and some protectors have a delay. So when you buy a surge protector see if it says how long a delay is, because the longer the delay the more current gets to the the device(s) being protected.
One thing home inspectors have been seeing recently are the newer whole-house surge protectors installed directly into the electric panel box.
Here the surge protector is the large, rectangular "thingie" on the upper right.
Can it protect against a lightning strike? Yes, theoretically, but lightning strikes have variable amounts of energy, and therefore variable joules are produced that the protector is trying to control.
Fun facts regarding joules:
- A nanojoule (one billionth of a joule) is the amount of kenetic energy produced by a flying mosquito.
- A kilojoule (one thousand joules) is the amount of solar radiation received by one square yard of earth in one second, during a sunny day.
- A gigajoule (one billion joules) is the amount of energy produced by one barrel of oil.
- A terajoule (one trillion joules) - 63 terajoules were released by the explosion of the atomic bomb over Hiroshima.
- A zettajoule (one sextillion joules) - earth's annual energy consumption is calculated to be 0.5 (one half) ZJ.
So, this was a lot of information about an important subject - SURGE PROTECTORS.
My recommendation: when you buy a surge protector look for the number of joules it protects (100 or more is considered good). The higher the number the better the protection (generally speaking). And also look for what the delay is - how quickly it works. Obviously, the sooner the better! Oh, a yottajoule (one septillion) is how much energy it would take to heat all of the water on earth 1 degree Celsius. That's a lotta joules! James Prescott Joule would be proud, to be sure.
Oh, when I played college soccer I did use a protector to dissipate a surge of energy around the family jewels. It fit inside my jock strap, and we called it a "cup."
Jay Markanich Real Estate Inspections, LLC
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560