Whole house surge protector

I have been considering a whole house surge protector for a while. Does anyone have any thoughts on this? Recommendations?

Both my parents have them (I may have had something to do with it...) and they're good in that they protect the big stuff, but they still suggest individual units for sensitive equipment such as computers. Some people ignore protectors entirely, so I'd rather have whole house than nothing if the individual equipment warning is going to be ignored anyways.

I have a whole-house unit through my local utility's subsidiary that does appliance and HVAC stuff. It isn't very expensive (monthly fee), and if any appliance get fried while protected by the system they cover replacement costs. Not a bad investment, especially since a neighbor a few doors up had to replace his whole HVAC system a few years back due to a surge.

It's probably a good idea, especially if you live in an area with a lot of lightning strikes like FL. OTOH, equipment actually damaged by electrical surges is pretty rare these days, although it is blamed for a lot of problems that are just "normal", "random" failures.

I would pass on the little surge strips, although as extension cords they are cheap enough that they are useful in that role. They can't absorb enough energy to do any real good, although the "insurance" some of them carry might be of some value to you. I am not sure just how you would prove that a damaged piece of equipment was caused by a failure of the surge strip to protect it from an electrical surge though.

The only good place for a whole house surge protector is right at your main panelboard. An appropriate one is not cheap - $200-400 is not uncommon. If you insist on installing it yourself follow the directions very carefully. How it is installed affects how well it can protect your home's electrical equipment.

Large online UPSes intended to supply entire computer rooms typically have two sections -- the inverter, and the battery cabinet(s).

It is possible you could find someone who wants to get rid of one of these because the batteries are dead.

But you could wire it up so that your entire house was on the inverter which would supply you with re-built, clean power.

-john

Be sure to check into how long it lasts, and how often you'll have to replace it.

Most power strip surge protectors are "consumed" over time mediating small surges, and have to be replaced periodically to be sure they have can still handle a big one.

I don't know if that applies to whole-house ones, so that's something I'd definitely look into.

While researching my reply I found a pretty good thread on this at dslreports from a couple of years ago: thread

Any such things worth the money will not rely on isolating the house but rather grounding the incoming power (they'll disconnect the house too, but the key strategy is to dump the incoming voltage/power spike to ground). They'll go between the meter and the circuit breaker box, often right next to the meter (since it's easier to install the ground cable outside than at the breaker box).

The most important part to look for is a huge cable or spike going straight down into the ground from the whole-house protector. This is the most important part and must be installed right. If a unit doesn't make big deal about the ground cable, leave it on the shelf. The rated lengths of this is in *inches*, not feet, so if some yo-yo wants to put the box in a convenient place and run a long ground cable somewhere else, hire a different yo-yo.

Think layers. A suppressor at the meter or the main panel and a suppressor strip is good. The large carbon bead unit rides in the panel where it takes the head off any large surges. The surge strips handle what it doesn't catch.

None of them work worth a damn if the ground path isn't solid. It doesn't matter how good a toilet flushes if the drain line is clogged. A good ground system makes sure there is somewhere for the excess energy drained off to go to.

Living in Florida and working with electronics I have noticed that while electronics do burn out with time the ones that are well protected last longer.

Surge strips should be marked with the month and year so you know how long they have been in place. It is really easy to plug one in and then forget about it for a decade. They need to be replaced regularly. How often you replace them depends on how tough they are, how many and how large the spikes they absorb are, and how expensive the gear they are protecting is.

I set up a hierarchy. My expensive gear gets high quality units and they gets replaced every two years. Less expensive electronics clusters get a cheaper units. Once the they have done their time the strips get used to protect ever less expensive devices. Over the years the household now has over a dozen units and there is at pretty much one on every circuit. Several two or more.

I have replaced the MOVs and other expendable parts in a couple of units but the suppressor strips are so cheap that it is more efficient to just buy new ones.

What you need to research is industrial power conditioning equipment.
The simplest form is a fuse box with a bank of MOV (metal oxide varistor)
such as http://www.littelfuse.com/metal_oxide_varistor.html

These suppress short term transient events (spikes with high voltage but short duration).

These are available as modules that a user can replace.

Apart from this there is little you can do that's cost effective.
Active suppressor devices are typically around $1000 per KVA and most houses are on the order of 10 to 35 KVA (connected load is what you are going to size for).

There is ample info on the net, but the idea is to have a balanced configuration protecting line to line (240 Volt) and line to ground (120 Volt).

You will also want to make certain your grounding electrode (ground rod) is sized correctly and has low impedance (The NEC allows in some cases 25 ohms) but you need around 2 ohms maximum.

Then you need fast acting fuses as MOV typically fail by shorting which then draws very high currents, so no dual element fuses, either single element or semiconductor type.

Any way you are also going to need a qualified electrician to install it.

Look around for Surge suppression system used in industry and you can get some "white papers" for additional background.

If you go the MOV route, your cost is going to be about $ 25 to $100 per KVA including wires, fuses and related glue (metaphor) to put it all together.

Other techniques exist but are very costly, such as constant voltage transformers, active (rectifier bridge and inverter) conditioners as well as line reactors.

We use this stuff in industry and depend on economies of scale to keep cost controlled, even then we rarely cover an entire power system (most plants use between 25 and 100 MVA = Mega Volt Amperes == not quite but almost mega watts to the non-technical).

Also one final note, if you suffer lightning problems remember power line coupling is not the only problem, cable, phones and other items such as antenna can route spikes in.

Unfortunately there is a lot of misinformation out there on this subject. Grounding actually has very little effect on how surge suppressors work. Lightning arrestors are a little different, and grounding is an issue with them.

There is no way to send the excess energy to ground. Just doesn't, and can't happen that way. Whatever energy needs to be dealt with is absorbed inside the surge suppressor. If it can take it, it works. If there is more energy than it can handle, it destroys itself trying.

The fact that the excess energy is not diverted to ground, as many people think, does not mean you do not need to consider a surge that may occur on your electrical line referenced to ground, but even then, the energy is absorbed inside the surge suppressor, even though the electrical path is to ground.

As someone mentioned, cheap surge strips often have multiple elements in parallel because MOVs have a definite shelf life and eventually will fail. If you put multiple MOVs in the surge strip, it will last longer because they won't all fail at once.

Nowhere in the NEC does it mandate any such thing. Getting your ground impedance under 2 Ohms is very difficult (25 Ohms is not all that easy), and serves no real purpose in any case, at least in a residential or industrial setting. For certain types of transmissions lines, yes, but not typical users.

MOVs do not "absorb" energy, they are not energy sponges, they are in fact voltage dependent switches connected to ground. When activated they form a simple voltage divider with your equipment on one side and the the ground path on the other. The lower the impedance of the ground path the more effect they are. Part of the materials fuse inside every time they cross the voltage threshold but they do not dissipate any significant amount of energy on their own.

They also do not have a "shelf life" they do not degrade over time on their own. They are worn down by activation and more energy they pass the more they are damaged. They are expendable. Which is why it is good to replace them on a schedule and not to depend on the little indicator light, typically triggered by a fuse, to tell you it is used up.

Also the grounding system is very much vital to most, but not all, power conditioning systems. These are more or less dependent on a ground system of some sort. Most need a least a nominal ground system to work at all and ultimately use the ground system to discharge and as reference.

Such conditioning systems that operate partly independent of a ground are pretty common in areas where soil conditions make earth grounding difficult. Sand hills and areas with non-porous rock, particularly if the climate is very dry, can be problematic to effectively ground.

Many of those systems are large, heavy and expensive. Pretty much beyond the scope of what people are likely to install. People are not going to install even a relatively cheap $5000 conditioning system in their house. On the other hand, assuming earth grounding is possible and the system is solid a $100 whole-house surge arrestor can provide a measure of protection. And if combined with a $60 plug-in surge arrestor it can go a long way toward protecting your $1000 computer or $3000 home entertainment system. Most quality surge suppressors have an array of chokes, coils and capacitors to help smooth the passed waveform so the functions are not mutually exclusive.

Nothing likely to be installed by a homeowner is going make much difference with a direct lightning strike. But even a moderately priced surge arrestor array can help with the much more common small spikes from distant strikes, POCO switching, and noise from neighboring equipment sharing the transformer.

Note that a whole-house surge protector is covered in the NEC under "Article 285 - Transient Voltage Surge Suppressors: TVSSs"

And yes, the NEC, at least for "rod and pipe electrodes", does mandate the 25 ohm resistance as the dividing point between using one or two grounding electrodes. It mandates that if you cannot meet a 25 ohm standard with one electrode it "shall be augmented by one additional electrode". (NEC 250.56) Note that it does not specify what the resulting resistance might be.

The other grounding methods, such as a concrete encases electrode, are assumed to be at least as effective as two ground rods 6' apart. Reference NEC 250.50 for further information. We pretty commonly drive one or more well pipes down to ground water to meet engineering specifications.

I'm looking at a 2005 edition, what I have immediately available, but suspect this hasn't changed in the current edition.

We watched an episode of Holmes on Homes & he added one to a house he was remodeling. Several years ago I had a amp for my stereo go out from a surge (lightning storm). Now when we have a
storm certain items get unplugged when we're home.

[quote=Art_in_FL
Surge strips should be marked with the month and year so you know how long they have been in place. It is really easy to plug one in and then forget about it for a decade. They need to be replaced regularly. How often you replace them depends on how tough they are, how many and how large the spikes they absorb are, and how expensive the gear they are protecting is.
[/quote]

I do have a "storm protocol" for summer thunderstorms - unplug the file servers, disconnect the cable internet feed - but I can't always be home for that.

Is there any test to see if the suppressors are still working? I sank some serious $$ into high-end surge protection strips (big metal units) but that was close to 10 years ago (as you said, set & forget). We don't have a lot of lightning strikes that come close to the house, but we do have enough line hits in the summer that we see some noticeable wallops on the lights, followed by 15-20 seconds of brownout and then dark.

I presume my suppression gear is kaput...

I would think ten years is plenty long. If those units use MOVs as their main mechanism I would go ahead and demote them. You say you spent a good amount of money.

Do these units have some sort of function indicators? If the indicator is telling you it is still okay, and you have a lot of faith in the brand and model, and that the indicator is telling you the truth, you could keep them in place and ride on.

There is no practical way of testing such units. So your operating on faith, company reputation, perceived risk, and how lucky you feel.

Then again ten years is a very long time in technology and consumer electronics. After ten years you might consider that you have got your moneys worth.

If you wanted to split the difference you could transfer the older units to less important equipment and bring in newer units to protect your most important electronics. There is some benefit to having surge arrestors on many circuits.