I have seen many recommendations to turn off appliances, etcetera after a power failure to prevent damage, etcetera caused by the "surge" of elecricity when power comes back on. I do not have a clear understanding of this danger.

Is there something you can install between your home and the "grid" to automatically protect your house and everything in it from such dangers?

Thanks.

Surge protection can be installed at a whole house level. There are several companies that sell these and you need to understand how much protection you need/want in order to select one. Most homes have 100 Amp service or lower so the uninstalled cost for a decent unit should be below $300. Professional installation is usually required since this installs between your meter and your fuse/breaker panel. Most surge protectors also offer telephone and cable TV line protection along with some form of status indication.

The electrical grid we draw power from is not a static system, it is dynamically regulated and adjusted to maintain the voltage levels we expect. During very rapid changes in demand (power failures / restoration efforts) or lightning strikes (which can also sneak in through the phone or cable lines) it is possible for your appliances etc. to be exposed to out of tolerance (i.e. high or low) voltage levels. These are surges and they can destroy any appliance or device if the current/voltage levels are driven outside the design tolerance levels.

A whole home surge protector is a good idea these days and I would still use a portable / powerstrip protector for any really sensitive electronics, like computers and flat screen TVS.

- Eric

Most newer homes have a 150A-200A service, not 100A, my 150A is the smallest anyone has ever seen.

While it's possible to have a power surge when the utility power comes back after an outage, it's more common in my experience to see power surges due to unexpected grid events (like mylar balloons shorting out power lines, a drunk driver knocking down a pole, lightning strikes, and so on).

All sensitive electronics should be connected via a good surge protector. That includes all computers and AV equipment. I've had good fortune with Trip-Lite and APC professionally.

A good whole-house surge suppressor sounds like a good idea, but I would also use individual surge suppressors in case something inside your house finds a way to cause a surge.

Make sure to check that the outlets you use are properly grounded if you want a surge suppressor to work correctly. It's a good idea to check this anyway. An outlet tester is cheap.

The current (ha!) edition of Family Handyman has a piece on whole house surge protectors. They described two options; one installed at the panel and they described how a competent diy'er could do it if their panel had the room and the other option was a protector at the meter which is a definite pro install.

Our next house will have it for sure. No more wallwarts!

I may be a bit dated - haven't been house shopping for nearly 15 yrs and trying to avoid the next round.

I suspect service size also varies greatly by local area standards and house size. I did a quick check and most of the newer housing divisions around here are starter/smaller family homes and have 100A standard with 150A or 200A as options.

In either case the cost for decent whole house protection is pretty reasonable compared to buying reliable outlet protectors.

- Eric

Service sizes are based on a calculation that is made according to the NEC. It has nothing to do with the age of the home, or even its size, although a larger house might have a larger service because the calculation ends up bigger.

Homes with gas appliances often do not require a very large service, but I think the smallest service the code allows these days is 150A for houses and 60 or 100A for apartments. I don't recall off the top of my head and am too lazy to look it up right this second.

Whole house surge protecters probably do a better job of protecting your stuff than the plug in units. Most modern electrical and electronic gear are pretty tolerant of the level of surges that the plug in units can protect against. It is all about how much energy the surge protector can absorb. The plug in units just do not have much capacity.

There is a lot of misinformation out there about surge protectors and even among people who one might think would know there are a lot of different thoughts on what is the "best" answer. I think the real answer is that no one really knows with any certainty, especially for residences.

One thing that is often a problem is the intersystem bonding. It is pretty critical that the grounding point for the incoming phone, cable, and or satellite lines be the same as for the structure's electrical system but it is quite common to see a seperate ground rod driven just for these connections. A very bad idea, but quite common.

Unfortunately, these kind of reports can be extremely misleading. Often if there are a series of surges on the lines coming from the utility, it is for a reason, and the utility is able to resolve the reasons for the surges. It is quite possible, maybe even probable, that the end of your problems was just coincidental to your purchase of a surge protector.

To be quite candid, the supposed guarantees of the companies providing these products are of dubious value. How would one ever prove that your device failed because of a surge the surge protector did not prevent? In fact, how would one prove a "surge" killed the device in the first place?

Tripp Lite and APC have both paid out on these guarantees that I know of. I have no data (anecdotal or otherwise) for others. I imagine that a competent electrical engineer can tell whether a power surge fried something.

I am a competent engineer and there is no way I could tell whether a product just gave up the ghost or was killed by a surge, short of some catastrophic failure. The typical failures of electrical and electronic equipment just do not lend themselves to any easy determination of what caused the failure.

I worked at a computer store in college, and we got several that were hit by surges usually during storms. Typically the power supply would be dead (MOV inside would blow), or the modem no dial tone as people would plug their power into a surge protector but plug the modem straight into the wall and it would take a hit, usually that's due to electrical storms.
During bad electrical storms it wasn't unusual to see burned components, sometimes blown right off the board (modem).
We had a burn in policy, any computer we fixed we plugged in and ran diags for 48 hours. So we might get one that won't power on and replace the power supply and sit it on the rack to run and if it passed that burn in test then it was probably just a bad supply. But if something else died during that burn in that was a sign of a surge. We would replace a second part and something else would fail. What happens is surges will get through and stress other components to where they fail shortly afterward.
So we had a form letter where it something like "I <techname> working for <computer builder> have diagnosed this computer and based on symptoms and experience have determined that it was damaged bu an electrical surge. Based on previous experience it is our recommendation that the complete system be replaced rather than repaired.
APC and Tripp Lite and Homeowners insurance usually always replaced the systems that I recall, I don't remember any disputing it.

Somewhat related, the only vendors I ever had issues with for warranty stuff was Sony, Microsoft, and Apple, they would fight every step of the way while other companies were usually pretty good about taking a computer stores warranty returns.

I also work in an electrical engineering (not household stuff) and generally it is pretty obvious if electronics have been subjected to significant over or under voltage (or current) conditions that damage components. It does take some detailed knowledge of the particulars of the system design (not just the circuit diagrams) and may require test capabilities not usually available to the "Geek Squad" members. I also suspect the effort required is high enough that most companies won't bother making the effort unless you are trying to get something really, really expensive replaced.

The other thing to remember (as ILBob pointed out) is that grounding is very important. A lot of the technology in surge suppressors is used for similar reasons in my field and I'll point out that even the best surge suppressors have limits and won't work if there are unprotected electrical paths to the device.

-Eric

dweste,

Although many people have given you good information, none of them have answered your question. When power has been out and comes back on, all of your appliances etc. are trying to start -- and so are everyone else's. The first problem here is not truly a surge, but a lowering of the line voltage, just when your items need a higher than normal current. This can (particularly in the case of motors (AC, fridg.) cause damage to the motors themselves. Worse on some than others. After that you can have a series of spikes (surges) as other equipment gets started and quits taking current and the voltage jumps up for a moment. The only way to solve this on a whole house basis is to take the house offline until the power stabilizes. There are units to do this, but sometimes the least expensive (and useful later) is an automatic generator cut away. It would normally cut the line power and go to the generator until line power is back on and stabilized. Most of them will do the same thing without the generator, and you can add the genny later for a super setup.

Respectfully,

Jerry

Not a direct answer to the original post but just wanted to chime in and say I agree with low voltage usually being more of a potential issue than other "spikes". Back in the 80's I spent several days on and off tracing down an intermittent issue with a Houston Instruments graphics plotter (about a $5K piece of hardware back in those days). Worked directly with HI several times before we solved it.

I went on-site to the client which was an industrial facility. Just happpened to be there late afternoon one day when the plotter started acting up. It would be in the middle of outputting a CAD drawing when all of the sudden the pen and paper would go haywire. The shop had mostly fluorescent bulbs and they flickered all the time so I didn't really notice anything from them. But they had a fixture with an incandescent bulb net to a door I just happended to notice dim about the time the plotter acted up.

So I asked the draftsman, "Does that (light bulb dimming) happen often?". His reply way, "Oh yea. Almost every day around this time just after they are changing shifts, they fire up the pots".

Had him get hold of the maintenace crew, they put a volt meter on the line, and sure enough, some significant voltage drops were present on the line sporadically.

Suggested he order a line conditioner/battery back-up for the plotter and a few days later, problem solved.


I have not been affected by a lightning strike personally, but know others (amateur radio operator buddies) who have had that unfortunate experience. Even though they claimed to have lightning protection for the antenna and had the station well grounded both electrically and via the chassis to a separate ground, a lightning strike to the home still took out their equipment. At least two have told me that their homeowner's insurance policy covered the loss. You may want to check if your coverage includes lightning and/or electrical systems damage.


Where I am located, most of the power outages are rare and very brief, many times just a few seconds. I have most of my main computer equipment, router, hubs, etc. on conditioned (good 60hz) battery backups like APC (No Affiliation). My radio equipment is ran off of a 12 volt (GlassMat) battery that is constantly charged from an AC source. Given that we have maybe four or five such brief outages a year, I have yet to lose any equipment to damage -- that sound you may hear is me knocking on wood as I type this :-)


Regards,

buckeye

+1. My thoughts exactly.

Is there any practical piece of equipment to auto-protect your house from this type of electrical variation?

You can go completely off grid & Go Solar,that would eliminate that worry!You could install a Parallel panel,it works mainly for Spikes(Up surges) but would have no effect for a down surge. Both would be Very costly at present,& each have their own Bugs to work with.You could buy a Gas fired Refridgerator that requires no voltage,it does have to be vented though,check out a store named Lehmans,they have supplied the Amish & Rural folks for a long time,Good Luck!

Be careful here confusing terms, a spike is not an 'up surge'. Surges and spikes differ in duration and require different methods to eliminate.