Lightning and neutral wire question

Re: Lightning and neutral wire question

Joe Herrmann

I, too, find it easier just to unplug...

Re: Lightning and neutral wire question

Barry Irby

Lightning is hard to resist. I'm not an expert but I think the ability of the switch to resist a strike depends on the gap in the switch. And you never switch the ground. Unplugging is vastly better. Much bigger gap and the ground is disconnected too.

Re: Lightning and neutral wire question

Josh Bowman

Chuck,

If you have a Jet or Powermatic, you're using 2 hot wires and 1 ground. This system doesn't need the neutral, since it's using the full 220 volts. So that gives you 3 wires that can be laid down on the disconnect. I mounted my 3 phase disconnect near the head where I can easily access it. Now I when I open the disconnect it's like unplugging it. I also have a 3 phase disconnect on my metal lathe which is 110 volt, with that one, I get the hot, neutral and ground.

At my house I've had a time with lightning coming in on neutral, ground, hot and even just through the air!

The last storm I lost my drill press VFD and just got it replaced, so now I unplug it, since the receptacle is near where I'd put a disconnect.

Re: Lightning and neutral wire question

Ralph Lindberg

Obviously Jet/PM is right.

But there are things you can do.

I'm, well, a Ham, a retired EE, former Electrician and I take few chances.

Inside my main power panel I have a high-end commercial surge arrestor that is wired to both hot's and the neutral (my exact model is no longer made, but there are similar ones)

My DVR-XP is connected to a commercial grade surge strip.

My band-saw or Grizzly 22inch lathe is connected to a 220V plug-in that is intended for 220V A/C units. This interrupts the power for 30 secs (? exact time) if the power exceeds either the high or low limits (Pipeman's Protect A/C )

Re: Lightning and neutral wire question

Bill Howatt

Given that lightning bolts can be in range of 1-10 billion joules (makes the 3K joule surge protector the TV is plugged into look a little feeble for a direct hit), many megavolts and many kiloamps, I wouldn't rely on a small switch with small contact separation for any protection if the hit is significant.

Safest way is to unplug which gives large separation and breaks all 3 connections.

Bill

Re: Lightning and neutral wire question

Dick Coers

My brother's house took a really close hit. When he came home in the evening, the first sign that something was wrong was the cassette tape from the telephone answering machine was on the floor. No idea what rpm that thing went up to, but the tape flew out of the machine.

Re: Lightning and neutral wire question

Guy Bratt

With out going into Bill's billions of joules and kilo volts and amps.

I think of lightning like this...

A strike can come through the air from miles away, that little gap, even one in an industrial safety switch won't stop its travel to earth.

I unplug and leave the cord away from the machine.

Re: Lightning and neutral wire question

John C Lucas

A friend approached me at the club meeting and said lightening had hit his Net and killed.the VFD. He got very little help.from jet a d had a very hard time getting a new inverted. Be said they were as ding one from China a d it won't come programmed so you have to.do it yourself. If you have ever seen one of those manuals there are about a 100 settings. Fortunately you only have to set a few but it's figuring out which ones that's tough. I always thought jet was pretty good at helping our customers but this doesn't sound good.

Re: Lightning and neutral wire question

Bob Macgregor

We lost a couple of cordless phones to a lightning strike a few years back. One of the phones was actually blown off the wall cradle and across the room. I was happy enough not to have been home for that one.

Re: I appreciate the replies...

Chuck Jones - West TN

Thanks for the comments and information.

I think I'm going to develop the same attitude toward lightning protection that I have about locks and security systems. None guarantee much protection, so why bother?

It seems to me that if I plug and unplug a power cord every day it will soon damage the plug or receptacle and cause other problems.

I was going to make the observation that being hit by lightning is a relatively low probability. But we've just learned that our son's house in Nashville was hit by lighting yesterday and received major damage; siding blown off, appliances ruined, computer systems knocked out. They both work from home so there were lots of computerized gadgets in the office. Luckily they were not hurt.

Re: Lightning and neutral wire question

Chuck Jones - West TN

John I have had good experience in my previous dealings with Jet, but my friend was not very impressed. He decided he did not want the hassle of finding and learning how to program an "off brand" VFD so he paid the price and bought one through Jet. He asked me to install it for him and I did. Here is what we found:

- New VFD has different configuration from original.

- Wiring diagrams that came with the replacement did not match the product.

- As you say, dozens of programmable values

- Virtually no comprehensible instructions on programming

We carefully drew our own diagram of the wiring and reasoned out where the wires should go. Made the assumption that the replacement was default programmed to some reasonable set of values. Held my breath and plugged it in. Everything works fine!

Just watch the weather channel

Dick Coers

No need to unplug every day. Just when storms are coming, or you are on vacation, etc. So unless you live in a rain forest, you can often go a week without unplugging. I've been in the same basic shop format in this house for 40 years. I haven't worn out a plug or receptacle yet.

Re: I appreciate the replies...

Bill Howatt

There are two factors about plugging/unplugging. Wearing out a $10 receptacle arrangement is pretty minor and it will take time to do it. The other factor is whether or not continually unplugging and restarting your VFD is a good idea. Lots of arguments but my opinion is that I leave mine plugged in all the time unless I know a storm is approaching or I know I won't use the lathe for an extended period of time.

The problem is that it is hard to gauge the level of protection you might be getting with protection devices. A lightning strike doesn't have to be a direct hit to do damage, just a hit somewhere along a power line will do it and of course, the closer to your house the worse the damage is likely to be. If nothing gets damaged you may attribute it to the suppressor but OTOH nothing may have been damaged without it.

The problem with the local suppressor power bars is that their ground line is small (relies on house wiring) and there is a significant distance to the supposedly good panel ground. For high-frequency, high voltage spikes this reduces their effectiveness but given the low cost they still are worth having. They may also offer connectors for TV cable, phone and ethernet protection as well.

The best solution for your electrical system is what is called a "whole house" suppressor. This is mounted beside your electrical panel and directly connected to the wiring - the hots via a breaker. This gets the surge when it first comes into the house and there is a short connection to the panel ground which is the best ground you have available. Still, if you get a direct hit it won't stop it.

Bill

I wonder????

Barry Irby

Doesn't the effectiveness of any suppressor bar or whole house unit depend on where the lightning enters the system? I got hit a few years ago and it came from the top down, knocking out a computer and a telephone and several other things. As far as I could tell it never got to the main panel. I wonder if a whole house unit would have helped?

At a friend's house it hit a tree and from that ran along his copper water line and jumped up to his car that was parked over the line. Blew out the entire wiring harness in the car. They tried to fix it but never got all the damage.

Re: I wonder????

Joe Bradshaw

I have been unplugging my lathes after each use. It's going on to eight years in my shop and I have not worn out either the plug or the receptacle. As an aside, the lathes at JCCFS are unplugged when ever there is a thunder storm an when leaving the studio at lunch and dinner and when quitting for the night.

Joe

Re: Just watch the weather channel

David Walser

It's a common misperception that power surges are solely caused by events external to the home, such as lightning strikes. That's not the case. About 80% of power surges are caused by things after the power line enters the home, such as a large electric motor turning on or off (such as an A/C unit, table saw, or air compressor). True, unless something is wrong with the A/C unit, the power fluctuations caused by its turning on and off are relatively small. But things do go wrong with A/C units and they can throw off a surge that will fry sensitive electronics.

Of course, external events, besides lightning strikes, can cause a surge. A traffic accident could down a nearby power line, for example. So, just paying attention to the weather isn't enough to keep your electronics safe.

Lots of things....

Ralph Lindberg

propagation time of the surge

clamp time of the surge device

entry to the system

on and on....

Some friends had an electric mower burn out, so the surge source was "inside" the house.

Needless to say their main-panel mounted surge didn't get a lot of that surge

But the computer and TV surge arrestors helped.

The last really serious surge I had before I put the main-panel system in was strong enough to actually blow up a couple light blubs (and kill a TV and a radio power-supply and....)

Re: I wonder????

Bill Howatt

Yes, it matters and in the case you describe it might have come in on the phone line if it gets connected to a modem and then runs to the computers. Having said that, if you look at all the power lines running around that might get hit a distance from your house such that a surge propagates down the lines there perhaps is a higher probability of the strike getting in via the panel.

My panels surge protection also has phone line protection on it but the regular phone line block has protection as well.

It is a game of probabilities and using these devices helps reduce the chance of damage but it cannot eliminate it.

Bill

Bill

What about Lightning Rods

Keith Newton

It seems like this would be good additionally along with other surge protection on the lines coming in.

Re: What about Lightning Rods

Bill Howatt

I was wondering about them and I can remember seeing lots of houses in the country with them when I was a kid which was a long time ago. I don't know if it is where my travels take me now or whatever, but I don't see (or notice) them all that much anymore.

Anybody have comments on the popularity of lightning rods these days? Maybe it is a geographical thing or maybe they are hidden better.

Bill

Door to door salesman

Dick Coers

When I was a kid on the farm, folks drove up all the time to sell or want to inspect our lightning rods. Of course, they always found something that was not right with the ones we had on the barn. Guess there is big city lightning too! Three major strikes at the same time.

Chicago lightning!

Excellent Product

Brad Vietje

One of the easiest and best ways to protect your home and specific devices is to install a few Midnite Solar SPD's -- surge protection devices.

http://www.midnitesolar.com/products.php?productCat_ID=23

I have no connection with the company, but used to sell and install these to protect sensitive electronics related to solar electric systems -- inverters, charge controllers, etc... Still would, but I closed the business 3 years ago.

Surges can enter your home or shop from the enormous antenna we call "the grid", or through the ground if lightning strikes nearby. These are nice because they have LED's to indicate they are still working, and if the light(s) go out w/in 5 years, they will replace the expended units. These are good for protecting any grid-connected property, solar or not. They retail for about $120 each.

Safe spinning,

Brad Vietje

Newbury, VT

Re: Lightning and neutral wire question

Brad Vietje

Ground and neutral are NOT to be bonded in any sub-panel. If your shop runs off a sub-panel fed by the primary distribution panel, grounds and neutrals must be separated. They are only bonded in the primary panel.

Just a thought, in case this had not come up before.

Safe spinning,

Brad Vietje

Newbury, VT

Re: I appreciate the replies...

Brad Vietje

By now an old thread, but something to think about:

It's not whether your house (or shop, or any other property) will be hit by lightning -- that's quite rare. Its whether the GRID will be hit by lightning, even at some distance from your property, which happens all the time. Your local utility shunts stray current to earth ground whenever possible, but pulses can, and do, enter your home from lightning strikes that happen nearby -- say w/in 10 miles or so. The electric grid is an enormous antenna, so if you have sensitive electronics you value, a surge protection device is a pretty good idea.

Safe spinning,

Brad Vietje

Newbury, VT