Leaving machines plugged in

Do you leave your welder, grinder, drill press, lathe, mill, etc. plugged in all the time?
We had a lightning strike. Luckily, it hit the house instead of my new
shop! :) It blew everything EXCEPT light bulbs. Some things were turned on but most were not. That indicates to me that there was a lot of arcing across switch contacts.
So, how great is the danger of burning some shop equipment? Has it happened to you? Or even one of Steve B's mythical friends?
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Andy Asberry wrote:

I unplug the machines I can, but the larger machines are wired in permanently. I switch those off at the isolator. I don't think there's a huge risk of your shop equipment being damaged by a lightning strike. It's much more likely with electronic equipment. Was most of the equipment damaged in your house electronic equipment like TVs, VCRs, DVD players, cordless phones etc?
Chris
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wrote:

Here in WA state north of Seattle all my machines are either left plugged in or are permanently wired. My building is all metal and all the machines are properly grounded but I know that's no real protection if powerlines are struck. We just don't seem to get that much lightning. I did visit a fellow in North Carolina who had his phone blow off the wall when the lines outside were struck. The scorched wall was pretty graphic. ERS
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Eric R Snow wrote:

A couple of extra grounding rods at the service enterance, and if you have a well, make sure the casing is grounded directly to the service enterance ground with at least a #4 wire, the larger the better with no sharp bends.
John
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To promote inferior and profitable products, some manufacturers will hype a protector as if it were protection. John has defined the protection. A protector is nothing more than a 'wire like' device that connects to protection. The protector (or wire) is only as effective as the protection it connects to.
The protection is earth ground - which is why better protection means enhancing the earthing - as John has demonstrated. A protector is simply a temporary wire connection to earth. But if that protector has no dedicated earthing connection, then that protector provides no effective protection. Plug-in protectors have all but no earth ground.
Serious protector manufacturers have names associated with responsible manufacturers - Square D, GE, Leviton, Cutler-Hammer, Polyphaser, Siemens, and Intermatic. Ineffective protectors are plug in types characterized by: 1) no dedicated earthing connection, and 2) manufacturer avoids all discussion of earthing.
Multi-layered protection will help. However many confused what is meant by multi-layered. Multi-layered is not about the protector. Multi-layered is about protection. Your building earth ground is secondary protection. Primary protection that a building owner must inspect: http://www.tvtower.com/fpl.html
Defined are two layers of protection. Each layer is connected either by a copper wire (ie CATV wire) OR is connected by a 'whole house' protector (AC electric and telephone). 'Whole house' protectors are so effective that one is installed, for free, by your telco. However, you - not they - are responsible for the earth ground. Not just any earth ground. Single point earth ground. All incoming utilities must connect, 'less than 10 feet', to single point earthing. If that incoming phone line does not connect 'less than 10 feet', through the protector, to single point earth ground, then you have a compromised protection 'system'.
Yes - 'system'. The protection for that electronic equipment is a building wide 'system'. The most essential component of that system is earthing.
That means even if a communication wire connects from one building to another, that communication wire must first connect to each building's earthing before entering each building. Earthing is what an effective surge protector does. Ineffective protectors completely avoid the earthing topic.
Point of use protectors hope you never learn this. They also hope you never learn that electronic equipment already has internal protection. Any protection that will work on the power cord is already inside the equipment. Protection that assumes YOU will earth the incoming transient before it can enter the building. Without a building wide protection 'system', then protection already inside equipment can be overwhelmed.
Concepts were well proven long before WWII. Your telephone switching computer, connected to overhead wires everywhere in town, need not disconnect during every thunderstorm. Disconnecting is dependent on something very unreliable - the human. Furthermore, do you really think a few millimeters separation inside a power switch will stop what three miles of sky could not?
Ham radio operators even demonstrated the concept. They would disconnect equipment from the antenna, put the antenna lead inside a mason jar, and still suffer damage. However when they earthed that antenna wire, then damage stopped. Earthing is the protection - not some protector and not a power off switch.
For residential buildings, Home Depot (Intermatic) and Lowes (GE & Cutler-Hammer) sell effective 'whole house' protectors. Other brands are available through an electrical supply house. But again, the protection is defined by the quality of earthing. Some examples of how that earthing becomes single point: http://www.cinergy.com/surge/ttip08.htm http://www.erico.com/public/library/fep/technotes/tncr002.pdf http://www.leminstruments.com/pdf/LEGP.pdf (page 14)
Notice in those figures: even ungrounded utility wires will carry destructive transients into a building. Every incoming utility must connect, 'less than 10 feet', to the single point earth ground. How that earthing is routed and connected is also important.
But again, the protector is not protection. Layering is about protection - not about protectors. Building owner is responsible for installing effective secondary protection - the single point earth ground. Building owner should verify that primary protection is also in place and properly connected. Protection is defined by and is only as effective as its earth ground - as John has demonstrated.
john wrote:

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wrote:

No doubt, I use to live in South Carolina and they have some unreal lighting storms that seem to come out of the clear blue sky.
All of my machines were always hot, now the horizontal band saw gets unplugged cause I can feel from the hair on my arms that it leaks.
I warn my 7 year old girl that they are on. After watching I robot she came into the shop a couple of days later looking over her shoulders and asked me if my machines would turn on her. :o) I reassured her that they are my best friends and they would never come after her cause she's my daughter. BTW she knows the machines are there to make robots, but obviously hasn't quite figured out that they themselves aren't.
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I'm in central Florida and we get a little lightning. I unplug my HF mini Lathe and my HF miniMill, because of the electronics, but I leave the Nichols Mill plugged in, as it has a double pole switch and a good ground. Then again I also leave my computer plugged in , because I'm to lazy to unplug it. gary

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Are "surge protectors" any real help in protecting electronics? Some years ago I had the details for wiring and components to make a home brew surge protector - lost with all the other "gonna do" projects.

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a proper surge protector will protect your electronics, but if you have serious lightning, it must be a multi-stage device - you put a heavy duty protector at the power panel, and then you can use a spark gap followed by a small inductor and then a MOV to protect the electronics.
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On Sun, 16 Oct 2005 22:28:13 -0700, "william_b_noble"

Lightning arrestors at the main power service and scattered through the house will help greatly in preventing damage to your 'stuff' from lightning strikes in the surrounding neighborhood, or that hit the power line a fair distance away.
But if you get a direct strike on your property, or on the power line within about a quarter mile of your house, all bets are off.
A healthy direct lightning strike right on the pole serving your house can easily overload or outlast the shunting capacity of any arrestor.
Unless you believe in spending large coin on some serious overkill - like the huge power utility duty arrestors and a big welded 4/0 copper cable grounding grid running around the perimeter of your property (the kind you'd use as a ground counterpoise on an AM Radio broadcast transmitter tower) to dissipate the charge.
Oh, and don't forget that the lightning strike can come in on the telephone and CATV lines, too. And can strike a broadcast antenna or satellite dish on the roof. You have to bond and protect these other paths, too.
I have the whole-house breaker-style Murray arrestor on our main panel to deal with smaller surges, and if we ever get a really big direct strike "Sh*t Happens". Luckily, lightning storms are a fairly rare occurrence in Los Angeles.
--<< Bruce >>--
--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
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Bruce L. Bergman wrote:

Lightning isn't the only threat. I used to loose an antenna preamplifier about twice a year until I figured out that static buildup was taking it out, usually after a strong dry wind. Grounding the antenna and mast fixed the problem.

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