joule is the unit quantifying energy, whether of electric, explosives, or _______!
when Anaconda W&C analyized the capability of 15kv shield systems in 1971, the elec energy was converted to joules -- the tech with me observing the actual tests done at ABChance company just north of Columbia MO stated that the sound of the cables failing within conduit sounded to him like 105mm howtzer shell explosions he experienced in WWII. we produced one fireball in excess of 15ft in diam due to shorting a cable in an open ditch, simulating a digin. electrocution would be instant -- burning in such a fireball would be horriable.
The higher the joule rating for the surge protector, the more energy it will divert before the protector failure.
Understand that not much will withstand a direct hit by lightning -- 1.2 million volts in 1/million second is the standard lightning simulation test voltage.
the better surge units protect L-G, L-L, L-N, have indicator lights to show that the MOVs have not shorted, have choke coils.
yes, the Belkin unit quoted is a strip type. The Panamax units I have & sold in 1988- 1995 were mostly boxes having but one outlet, but I have one with 4 outlets in a square box, prerunner of the strips.
One can buy several strips at $30 each vs $220 for whole house protectors. Besides, how many are comfortable working on the service panel? And, the whole house protectors do not seem to have the capacity of the strips. Again, get the highest joule rating, the lowest clamping voltage.
cem, I agree with everything except the strips. The OP wants to protect the electronics inside the furnace/ac. Can't do that with plug-in strips. In most places code requires hvac to be hard wired.
If he has the knowledge and experience to do electrical wiring, he can install a whole-house protector. If not, he has to hire an electrician. My electrician would charge $100 to install a whole-house protector. Less than 30 min work plus travel.
Putting strips on every appliance in every room gets expensive in a hurry. And ugly. Whole-house protectors are not that expensive. Here is a 2700 J device:
Very easily done have a whole house surge protection device installed. Does not cost much to have one installed!
Heres's a few!
[Edited by kevinmac on 08-29-2005 at 11:34 AM]
Isn't there something better besides MOV? MOVs wear out, sometimes quickly in a few months or weeks. After that they offer you no protection. It all depends on how stable your line voltage is. When the MOVs wear out on the cheapie models you don't even know it. You think you are protected but you are not. They need to be tested often and I don't think they are a reliable solution.
Daveandjulie, if you don't know something, ask. Otherwise you look foolish. Where do you get these preposterous stories?
No, MOVs do NOT wear out. They simply fail if a surge exceeds their capability. If the surge does not exceed their capability, they remain good. Buy the kind with LED status indicators and you can see if they are still good.
Yes,there are many other kinds of surge protectors. The MOV is just the most common. Do an internet search and learn. Plenty of info available if you make the effort.
MOVs have been in use for over 50y --
Panamax would have declared bankrupcy by now because of having tens of THOUSANDS of MOVs in service!
like stating that the cpu wears out because of the number of calculations it does
Dx (Here we go again with more pathetically ignorant advice.) You need to take your own advice.
MOV's do wear out. Over a history of surges the MOV's supression Voltage begins to lower. In other words, the voltage at which the the MOV begins to pass electrons thru it gets closer to the operating line voltage. This actually makes the MOV more "sensitive" to over voltages for a while. The problem comes when an repeatedly surged MOV begins clamping at the operating voltage. It goes into a run away condition and fries it's self. That's why you what an indicator lamp. The operating life of a MOV depends on the number and severity of surges.
As for joules, ANSI and IEEE DO NOT rate surge protectors by Joules because it's impossible. MOV's do not conduct linearly. The Joules handled by a MOV for one surge waveform can be drastically different from the Joules handled by a surge with a differnt waveform. The MOV manufacurers calculate their Joule ratings with a 10/1000ms waveform. True lightning type surges are closer to a 8/20us waveform. That's alot less energy. The surge protector manufacturers add up all the MOV joule ratings inside and post the total Joule rating on the package. Somebody like Dx comes along and thinks that the more Joules the better the protection. What really counts is the MCOV, and Max surge current. If you buy a whole house surge protector with a max surge current rating of 50,000 amps per line and a MCOV of 130-150 volts, and have a good ground, you will be able to control 99% of most surges and cut them off before they do any damage. Surges higher than that past the service entrance are rare because of the previously mentioned flash over in the fuse box, insulation burn thru to ground, and impedence of wiring diverting a large part of the surge.
That's what I was saying. If your line voltage is perfectly constant a MOV should last a very, very long time and be ready to do it's job when the time comes. That's not reality though. My concern is mainly that people will buy a cheapie outlet strip and assume that the thing will protect whatever they plug into there forever, and that is simply not true.
People used to send me equipment that had been affected by a surge and claim that it was plugged into a surge supressor so it should be under warranty. I would always as, how old is the surge suporessor and when was the last time you tested it? That usually shut them up.
I agree that MOV's implemented properly work perfectly fine. I kind of asked a rhetorical a question there. I know other types exist, I was just trying to stimulate a discussion of the other types so that I myself could learn more about them as they apply to home electrical services. Some B(l)ose speakers use gas discharge systems to pretect them, for example.
That's why there are other types of MOVs such as TPMOV's
Show me where you learned this.
Originally posted by baffin789
MOV's do wear out. Over a history of surges the MOV's supression Voltage begins to lower. In other words, the voltage at which the the MOV begins to pass electrons thru it gets closer to the operating line voltage.
Your Quote. "Do an internet search and learn. Plenty of info available if you make the effort."
OK, I'll bite. Here is a good article from IAEI:
Quote from the article:
"Degradation of MOVs
It is well-known that MOVs experience degradation due to single and multiple current impulses. The test results documented in Mardira, Saha and Sutton show that MOVs can be degraded from an 8/20us surge current at 1.5 times the rated MOV surge current. A 20 mm MOV with a 10 kA surge current rating will be degraded if a 15 kA single pulse surge current is applied."
OK, it degrades when subjected to 50% overload. Is this "wear" or failure? Hint: How many products do you know that are NOT degraded when overloaded 50%? How many remain functional at all?
I propose an analogous experiment. You sit in an armored vehicle. I'll fire a few projectiles at it, each with 50% more kinetic energy than the armor is rated for. Then you can tell us if the armor was overloaded and failed or was just "worn"
Here' a wealth of surge info.
There's nothing wrong with MOV's. Even the utility companies use them on their distribution and transmission lines. Just be aware that they can go bad. Especially, the equipment based surge protectors.
I read an article awhile back about the Department of Defense having problems with surge protectors on Faxes, Copiers, and Computers catching fire. Turned out that the Specifications for the entrance protection of the huge building was a Clamping Voltage of something like 500V. All the hundreds of surge strips in the building were clamping at 330V or less so that every major surge the building took was clamped by the surge strips closest to the entrance. The entrance surge protector was never reaching its clamp voltage. After several good surges, the closest surge strip would burn out, some of which caught fire. Moral, keep you entrance clamping voltage at the same clamping voltage of the equipment strips.