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.