Lightning strikes and brown outs

Do you mostly charge at home, or other places?

If at home, how's the lightning protection on your house? A good, well-grounded surge suppressor at the service entrance, and maybe another TVSS on the branch circuit leading to the charger wouldn't be crazy. That's just good protection for all the stuff in the house.

I would imagine the charger is smart enough to behave during brownouts, but I don't have a documented answer.

-Chap

 

@jerrymildred has a pip and lives in tampa. also knows a thing or two about electrons.

 

We are at least one of the lightning capitals. Denver along with several places in Africa are bad, too.

I do have a whole house surge protector, but I haven't gotten around to installing it yet. I think you do raise a valid concern about a near hit getting through the EVSE and into the car while it's plugged in, especially if it's charging. I'm not worried too much about brownouts, but the lightning is a concern. Maybe I'll get after that surge protector now before the next storm gets here in an hour or so.

 

There is NO protection from a direct lightening hit........or one that is a few hundred feet away.

If I had a plug-in vehicle, I think I would be manually setting the charge instead of using a timer.
The odds of damage are tiny.......but the price would be HIGH.

Might want to check your car and home insurance to see if either would cover lightening damage while plugge in.

 

Bought a service entrance surge arrestor for a friend about 14 years ago just as we were replacing her old 1970s-technology gas furnace with one of the new all-computerized wonders. Seemed like an appropriate time to think about surge protection.

Then it didn't get installed for months. It was actually sitting, in its box, on top of the new furnace.

What finally got it installed was the thought "how silly is it going to feel if this spiffy new furnace gets zorched while a surge arrestor in an unopened box is sitting on it?"

I recently noticed the protection LED on that arrestor is now dark, so her house has been protected by it at least once since it was installed.

Now she's procrastinating about replacing it....

-Chap

For anyone who hasn't noticed already, the scansion of "lightning strikes and brownouts" matches that of "heffalumps and woozles."

 

My phone answering machine regularly get fried, the phone line was grounded to to the electric utility ground, the electric utility was frying the phone, gave the phone it’s own ground, end of problem, yes, lightning is dangerous, yes lightning rods work, keep the connections clean, and don’t use the electric utility ground for the phone system

 

Hmm ... I'm in no position to question that what happened to your answering machine happened, for whatever reason, but separating the grounds is really not the answer. That was an old practice, but based on much improved current understanding, the codes have all moved to common intersystem bonding. You really do not want your phone, cable, electric service, etc., to all be going to different stakes in the ground.

Why? Well, any time lightning-sized currents are flowing through the ground, the difference in potential between where those different stakes are driven in can hit hundreds or thousands of volts. And lots of gadgets these days (like answering machines, TVs, etc.) will be connected to more than one of those systems, meaning the huge difference in ground potential is brought right into your electronic device.

So the best practice is that there is one grounding electrode system, and it is made up of all the bits and bobs touching earth that could practically be part of it, all securely bonded together, and all the electrical and comm system grounds are brought to it at one common point. (Why one point? Use two or more, and you've made a loop. Harmlessly at ground potential all the way around, of course—at least until some local lightning current makes a high slew rate magnetic field ... and then, well, induction is a real thing.)

That does leave the mystery of what was happening to your answering machine in your particular situation. I would hazard that there is still some part of that story that hasn't been discovered yet: some other issue with how the grounding and bonding was done at your house, or at the electrical service connections. Going to your separate phone ground has seemed to relieve the symptoms, but maybe has not led to the underlying issue yet.

Here are some slides about the common bonding provisions in the electrical, telecom, lightning, sprinkler piping, and gas piping codes.

-Chap

 

I've wondered about the risk of leaving the J1772 plugged in after charging completes. This makes it easier to start pre-conditioning. Now it makes sense to unplug when charging completes and lightening conditions are predicted.

Bob Wilson

 

We had the main water line replaced with a copper pipe. With a dielectric junction to the original galvanized piping in the house. The grounding system, such as it was, used the house water pipes for a ground.

I don't think even the main entry box was grounded when it was installed in 1957.

I guess the message is that part of installing a charging outlet should be verifying the grounding system. As a minimum, any metal cold water piping should be connected to a ground rod.

 

Yes it IS in many cases. Especially if the electrical service wiring is OLD, making it likely that that ground really isn't a good one.
AND......voltage surges are much more likely to come in on the electrical service since most phone wires are buried these days.
THEN......when you are dealing with MILLIONS of volts going to ground on that service rod, there might be a significant voltage present at the top of the rod where the phone line is connected. All grounds are not created equal and unless you have interconnected systems that require a "single point" ground, they are best kept separated.

 

Pace Sam, it's no longer exceptional systems that require intersystem bonding; it's been code for ten years now. Before being codified into the 2008 edition, the requirements went through plenty of review, as the evidence was mounting that the kind of ground separation Sam advocates here was exactly what caused the magic smoke to get let out of things more often than not.

A voltage is always a relative measurement. A big wave rolling in isn't necessarily a big problem if everything rides it together, but if a (let's use Sam's figure) MILLIONS of volts wave rolls in on a power service with its own ground electrode, and not on another system with its own different one, and you have a device (answering machine, cable box, computer, etc.) with connections to both of these systems plugging into the back about an inch apart ... fun times ensue.

Now, Sam's point:

may be well taken. If the existing grounding sucks, then blindly adding on to that system following the 2008 or later code, without finding or fixing the issues, might not work out best. If the grounding can't be fixed, then one might argue for a variance from intersystem bonding as some kind of "fight suckage with suckage" solution. But it would be better to fix the problems; sucky grounding will cause problems with more than intersystem bonds.

Both the quality of the grounding electrode system and the impedance of the ground wiring inside the building leading back to it can be tested. Both tests require somewhat specialized instruments, but a friendly neighborhood electrical contractor may well have them. Both kinds of tests can be useful in an older house to see if the systems are still meeting performance specs. The oldest sort of tester for the electrode system would only work with the house isolated from the service (only convenient during new construction), but the newer spiffier ones don't require that, and even those are coming way down in price lately, as electronic things do.



The intersystem bonding termination is there to support the connections "required in Chapter 8 and 770.93", and where those sections talk about connecting the communication grounds to the IBT, they have the word shall (Code-speak for "not a suggestion"). If there isn't an intersystem termination point provided but there's an existing grounding electrode system, the comm lines "shall" be grounded to that, in any of several acceptable ways, at a point near where the service does. Either way serves the ultimate purpose of having all the stuff in the house ride any incoming waves together, instead of being exposed to huge voltage differences between systems.

-Chap

 

If you have two ground rods about 50 feet apart and bring a wire from one to the other, you can jump a pretty decent spark between them. I think I measured over 40 volts between to grounds that way recently.

 

I would say that one of those grounds is not very good, and that might be the case BUT it probably really indicates that one of the things tied to one of those rods has a SERIOUS leakage current to "ground" that needs to be fixed.

 

There are currents flowing in the ground in various directions all the time. That's the basic reason the instruments for testing ground electrodes use a frequency like 135 Hz in the US, chosen to be different enough from power line frequency (and the 2nd and 3rd harmonics of line frequency), and the detectors in the instrument are all synchronized to that oscillator so they only measure the voltage and current due to the instrument itself. (The ones built for UK run at a different magic frequency chosen for not matching 50 Hz and its harmonics.)

Even so, there can be cases (especially if you are near some sort of industrial facility or a substation), where the manual for the instrument just has to say stuff like this:



-Chap

 

My house is now 40 years old. When it was built, the "grounding" was to the copper pipe coming in through the foundation. It turned out that this pipe was connected to the water meter in a pit and a PVC pipe then ran out to the water main leaving the house ungrounded.

There were two close lightning strikes over a 30 year period that caused damage to any system on two external grounds (Phone Modem, any surge protector, TV, etc). I discovered the problem when the PVC pipe developed a leak.

Now there is a copper pipe (restoring the house ground) out to the main and I have a whole house surge protector wired in my power distribution panel as well as arc fault or ground fault breakers on all AC branches. I do not expect further lightning issues.

JeffD

 

when there isn't city water, most electricians just drive a ground rod and clamp to it. no one tests with a merger, and inspectors don't care.

 

The code does permit, nay encourages, nay even requires, the water service to be part of the grounding electrode system, when the water service is metallic, but does not allow it to be the whole system. 250.53(D)(2) (2008 edition) says "A metal underground water pipe shall be supplemented by an additional electrode of a type specified in 250.52(A)(2) through (A)(8). It probably wouldn't be hard to drive in a rod and bond it in to your existing system.

The Handbook has an interesting note about why that rule is in place: "The requirement to supplement the metal water pipe is based on the practice of using a plastic pipe for replacement when the original metal water pipe fails. This type of replacement leaves the system without a grounding electrode unless a supplemental electrode is provided."

Right ... between the contractor, the inspector, and you, you're the only one who has to live in the house long-term and hope the work was done right. The others will typically act like they don't have to, because they don't.

I once had a plumbing contractor out replacing a bunch of gas piping, and noticed they showed up for the last (scheduled) day of the job with no air tank to do the (code-required) pressure test of the new gas piping. When I asked about that, they quickly phoned their office to have somebody drive out with an air tank. They were then on the job an extra day fixing the leaks it revealed. No wonder they'd have preferred to skip it....

-Chap

 

New construction of a radio station. Two ground rods. Nothing else connected to them.