I have a ESD Wristrap that is earth grounded (no resistor) to protect several development boards I have. This has also made me inquire into what happens if there is a lightning strike in my immediate area next to my home, electricity would bridge a low impedence path from any wetness on the ground and in the ground through the earth ground spike in the ground and into someone’s body and dissipate back into the earth. Since your body is essentially a resistor network and depending on your orientation, you could get shocked or killed. But also household appliances have earth ground connections on them. If you were to touch a earth ground based appliance during a thunderstorm, its likely to kill you then protect you.
So my question is this. Why isn’t there anything listed in the electrical code for homes that the earth ground spike must be fused or a resetable fusable connection?
1 Like
Hello @ubsanders,
Thank you for posting to DigiKey’s forum.
The voltage and current from a lightning strike exceeds the rating of standard electrical fuses.
Additionally, lightning is more likely to strike taller objects before reaching the electrical wiring inside a home. Someone may install a lightning rod to redirect the lightning. Typically, the protection of transient voltage surges is usually covered by the fire code.
If your climate is more prone to lightning, the fire code sets up guidelines for preventative measures such as: surge protection devices, proper grounding to dissipate energy from lightning strikes away from buildings, and overcurrent protection.
1 Like
Many ESD Wrist Straps come with a 1MOhm resistor built in for this very reason.
Here is options we have available with a 1MOhm resistor.
Although statistically the greater danger is accidentally touching 120/220VAC ( or any live circuit ) while you’re wearing a wrist strap.
I would elect to not wear a wrist strap of any kind though if a thunder storm is within ear shot.
1 Like
That’s true, they do (or most) have the 1M resistor. However, the body effect comes into play with voltages high enough for a lightning strike, it will pass over the component and shock you. I won’t wear during thunderstorm.
1 Like
If you’ve ever seen high speed cameras that capture lightning strikes, they can persist for over a few seconds, or very short period of time. But there are passive components that blow (or create an open circuit) when they fail or fail open instead of creating a short circuit. My question is, and propably someone with a PE license who knows the electrical code, why are there not options to protect this earth ground spike to open when a surge of current could kill someone? It’s merely an unprotected copper wire into the house connecting to the dirt in the ground. All your earth ground appliances then become a deadly component inside the house, if touched during a lightning storm.
You are a relatively high impedance path compared to an earth ground path. Lightning will choose the lowest impedance path, and that will be the earth ground path rather than you if you’re in a house.
If that path opens, via a fuse or whatever, then all bets are off. You might then become the lowest impedance path to ground and the lightning may choose you. You definitely don’t want the earth ground path to open.
