Just curious what you guys/gals do when you have lightning in the area. Yesterday I was in the shop and we did have some lightning in the, doesn't happen often though. I typically throw the breakers to the 240V outlets (I don't get too concerned about the 120V outlets) when that happens and don't use the power tools while the storm is going on. Do you do anything special?

It's either my pure ignorance or something else Fred, but I never even thought of it. When I had my 240v machines in my shop and all the other machinery I used to own, I remember working right through lightening, hmmm. Should I have been concerned?

No idea, that's why I asked for opinions. I know I've had household appliances damaged by lightning strikes, hence my caution with the power tools.

Never gave it a thought, Fred. Only have one 240 device, the air compressor. The 200 amp breaker box is grounded. Wouldn't that protect it? 

The biggest concern in my shop is the variable drives.  They are vulnerable to lightening and voltage surges.  I have always been anal about unplugging all my machinery when leaving the shop.  Most of my machines are on castors and rolled out for use and I usually only plug a couple in during a session in the shop.

 

I lost a drive on my Delta 46-460 lathe when a storm blew up out of nowhere and knocked trees and power lines down.  I think it was a power surge in the fray that got me.

 

 

Edited October 22, 20196 yr by HandyDan

30 minutes ago, Fred W. Hargis Jr said:

I know I've had household appliances damaged by lightning strikes,

I have for sure, recently a stove digital panel burned out due to a surge, not lightening related but a surge nevertheless. I should take heed and translate that to caution during lightening storms, note taken to self.

Great topic Fred.

One the east coast, thunderstorms are just a fact of life. I don't worry much about power tools but computers/TVs will get unplugged during especially nasty storms.

I think might have added more of my concern to the discussion. Many tools have electronics anymore to run them....and that might be my concern.

We took a lightening hit a few years back, took out a good surge suppressor strip, home entertainment stereo system, computer, but the TV which was on, and plugged into the same surge suppressor strip survived. The stereo, and computer were turned off at the time.  

There is no explaining what lighting can do. Like Larry said it can skip a sensitive piece of electronics and take out the stove and fan or melt the household wires. Because of the control box on my PM 3520B I unplug it every day when I leave the shop as DAn said power surges can easily get to that box. At one time I would go around and unplug all the electronics but that did get old.

Where is that Artie?  I am wondering what he would say about lightening taking the shortest route to ground.  Hmmm. don't know.

 

Unplugged is the only guarantee that lightening won't damage anything. But, what are the odds you will get a lightening strike ?

4 hours ago, Al B said:

But, what are the odds you will get a lightening strike ?

Having mentioned it, for me 1 out of 2 chance.  Just my luck.  

I lost my last shop to a lightening surge. It melted the breakers and just kept feeding line Voltage through the meter and was like an arc welder in the wall.

The State Elec./Fire inspector said that there is no overload device to trip if it feeds into the panel through the meter. A main breaker in not protection from line voltage surges.

Just saying,

Herb

Unplugging or physically disconnecting equipment from the wiring is the safest way to try to prevent damage from lightning. It has passed through meters, breakers, switches, surge protectors, etc. I actually worked on a home where the owners had mounted a 10 foot piece of conduit across the joists in the attic, to hang clothes from. They got a lightning strike that went through the roof to the conduit, melted most of the conduit, and started the fire. This was just a piece of metal, not grounded, or connected to anything but wooden joists. There are not a lot of hard and fast rules with lightning. Electronics fare much worse than wiring against lightning. If you’re inclined to, I would unplug all the expensive (by expensive I mean anything you’d mind having to replace) equipment you own. I do not unplug anything during storms, but shopwise, nothing stays plugged in anyways. I guess I can look at that as one of the advantages of having a small shop. In theory lightning (or for that matter, all electricity) looks for the path of least resistance. Supposedly, lightning would be directed away from equipment that is plugged in or connected to a circuit, by it’s ground. Lightning can have so much power/input, that it basically overflows the circuit/system and disperses in all directions, even away from ground. I dunno what most insurance policies cover regarding lightning damage. When I had a boat, and got stuck on the water during storms I would try to anchor up in the sail boat mooring field. I would also lower all antennas so they were horizontal to the sky, make sure there were no fishing rods in rod holders, and generally not have anything pointy, sticking up. 

Sounds like tripping the breakers off is only protection against any system surge then, and doesn't help with the lightning. I wondered whether it would pass through a tripped breaker. Thanks!

This picture is from a few years ago.  This shed is not wired for electric.  It is beneath a large Beach tree which was not affected by the lightening.  The lightening did travel to the next shed which is wired for electric and attached to the pole style building I use as a metal shop and tripped the breaker for the garage door opener in that building.  It then traveled 75 feet to the house and put the portable phone out and burned the switch on the surge protector strip for the computer equipment.  It did its job and the computer was fine.  Lightening doesn't happen often but sure does weird things when it does.  When I replaced the siding on the shed I had to cut it into smaller pieces to set it out for the trash.  It would not break by bending it but the lightening blew little pieces all over the yard.

 

29 minutes ago, HandyDan said:

This picture is from a few years ago.  This shed is not wired for electric.  It is beneath a large Beach tree which was not affected by the lightening.  The lightening did travel to the next shed which is wired for electric and attached to the pole style building I use as a metal shop and tripped the breaker for the garage door opener in that building.  It then traveled 75 feet to the house and put the portable phone out and burned the switch on the surge protector strip for the computer equipment.  It did its job and the computer was fine.  Lightening doesn't happen often but sure does weird things when it does.  When I replaced the siding on the shed I had to cut it into smaller pieces to set it out for the trash.  It would not break by bending it but the lightening blew little pieces all over the yard.

 

Wow. That is truly scary.

 The only way that I think you might be 100% safe from a lightning strike would be lightning rods across the peak of the roof connected to rated wire down to the ground. I've been on some jobs, a casino comes to mind, that they installed lightning rods every 50' around the perimeter of the roof and on top of each HVAC rooftop unit. Everything was tied together and the wire, which is more like a braded cable, was brought down at each outside corner of the building. This is all independent of any grounding within the building.

 

On 10/22/2019 at 8:41 AM, Fred W. Hargis Jr said:

I typically throw the breakers to the 240V outlets (I don't get too concerned about the 120V outlets) when that happens

 Turning off the breakers should solve the problem but that's not to say that lightning wouldn't travel through an open breaker.

 In this case I think there is more of a risk of loosing one phase while the equipment was running during a storm. You would realize this problem pretty quickly because half of your lights & outlets would quit working. On a 3 phase system, typically commercial, motors would still try to run with a lost phase.  

The town I work for is a tree town. They don’t cut down or trim the trees, even the ones affecting the utility wiring. So when we have wind storms/blizzards, large numbers of power failures. We have installed gear that shuts down the service if one phase drops out. We were losing too any 3 phase motors due to single phasing during power issues. The enormous voltage/energy that lightning has can easily travel through open breakers/switches. I believe you need one inch of air to insulate 10,000 volts, so 100,000 volts can jump through slightly less than 10 inches.