We're moving into a house that has older two-wire ungrounded wiring. Short of the expense of rewiring the entire house, I'd like to make it as safe as possible for people and equipment. I've already put in GFCI outlets in bathrooms, kitchen, garage, outdoor locations. So from a people safety perspective I think that's about as good as we can do, and grounding would not improve that situation.
Now for equipment, I'm thinking about a panel-based whole house surge suppressor, since the lack of grounding will defeat any point-of-use surge suppressors. There seem to be quite a few units available with similar specs: clamping voltages in the 400-500V range, energy dissipation on the order of 1000 joules, maximum current 50,000 amps,
Whole-house surge suppression is a good idea and that is based on personal experience.
130 volt clamp is too low. 70 joules is too low.
There was no Internet when I installed my first unit and I went to the best electrical supply house in my vicinity and talked to those folks. Now, you can Google this to death.
Lack of grounding will not "defeat" point of use suppressers. Those suppressers will still act to suppress differential surges on the line between neutral and hot which are most likely to cause damage to the connected device.
Without a ground that can't do anything about common mode surges where the same surge voltage is present on both the hot and neutral however these surges are less likely to damage the connected device unless it has a ground connection like a CATV connection.
I think I can safely say I've googled it to death already. I couldn't find any information on the Tytewadd device except from the manufacturer. Why is a low voltage clamp bad? I'd think that it would be better to clamp as low as possible.
I asked a local electrician about installing a whole house surge suppressor and he said he hadn't heard of them, and I can't find a local supplier that stocks them. I guess that's because we're in a low lightning risk area (we're lucky if we get one or two thunderstorms per year), but it still seems like cheap insurance. On the other hand, if these units are not effective for protecting electronic equipment, then I'm back to square one.
Hmmm. Some surge suppressor power strip vendors specifically say that they offer no protection and no warranty when used in an ungrounded outlet. Are you saying that they can shunt current between hot and neutral in a differential surge? I thought that all surges were shunted to ground?
Common mode surges are a most typical source of electronics damage. Point of use (plug-in) protector would do what already exists inside appliances. Appliance protection is typically so superior that a surge, incapable of damaging that appliance, can still cause a plug-in protector to smoke. This undersized (smoking) protector gets the naive to promote more sales of a so profitable and ineffective product.
Take a $3 power strip. Add some $0.10 parts. Sell it for $20 or $120 as a plug-in protector. Do anything possible to avoid discussing THE most critical component in every protection 'system': earth ground. Amazing how word association (surge protector = surge protection) replaces science to promote myths.
Appreciate further problems with plug-in protectors even 20+ years after UL1449 was created (because this happened so often). Would you put these on a rug or on a desk full of papers?
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Earthing is the most essential component in every protector system. Industry professionals, your telco, AC electric companies, commercial radio and TV broadcasters, ham radio operators, and even Ben Franklin demonstrated this all so necessary 'system' component. Do they install plug-in protectors? Of course not. No earth ground means no effective protection. True 70 years ago. Now essential for homes due to something new - the transistor.
Yes, lack of grounding will not defeat point of use suppressers because those grossly overpriced protectors don't even claim to protect from a typically destructive transient. But then don't take my word for it. Where does it list each type of transient with numbers to define protection? It does not. They hope you will 'assume' it is a complete protection solution. Assuming is what recommends plug-in protectors - myths based only on assumptions that even the manufacturer does not dare to claim.
How to quickly identify an ineffective protector: 1) No dedicated earthing wire. 2) Manufacturer avoids all discussion about earthing.
Effective protection earths before transients enter the building - so that transients do not overwhelm protection already inside appliances. Transients that don't enter a building therefore do not find destructive earthing paths everywhere inside that building.
Effective protectors are also sold under names of responsible manufacturers such as Square D, Cutler-Hammer, Siemens, Intermatic, Leviton, and GE. Effective protector solutions will not be found in Radio Shack, Sears, Staples, Best Buy, K-mart, Office Max, Bed Bath & Beyond, Wal-mart, or the grocery store. How do you know? Where is that all so necessary earthing wire?
Solutions are sold in Lowes, Home Depot, and most any electrical supply house. They have been necessary since the 1970s - when transistors began appearing in homes. Home earthing system must both meet and exceed post 1990 National Electrical Code requirements.
Above is > Lack of grounding will not "defeat" point of use suppressers. Those
A typical cheap suppresser has three MOVs, one hot to ground, one neutral to ground and one hot to neutral. Obviously the hot to neutral MOV can clamp transients that are differential across the hot and neutral regardless of the presence of a ground connection. Suppressers using gas discharge tubes would be similar.
If the surge is common mode, raising the voltage on both hot and neutral and the device connected has no ground connection anywhere like a CATV connection, then the entire device will jump to the higher potential which should cause no damage. The hot-neutral suppresser would still attempt to clamp any excess imbalance so the device should not see any effective over voltage unless the surge exceeds the suppressers clamping capacity.
As for warranty, certainly the suppresser can't work to it's full design capacity without a ground so they don't want to warranty anything. That doesn't mean that the suppresser will be useless without a ground.
[lotsa good stuff re:grounding snipped]
'Scuse me just a second, but even though the O.P. referred to their house as having "older two-wire ungrounded wiring", that doesn't mean that their service is *ungrounded*, only that there's not a separate ground and neutral, correct? So their electrical service *is* grounded (should be, anyhow).
Care to explain how a common mode surge can damage a device that has no ground connection?
A device with only two electrical connections, hot and neutral, does not care in the least what the voltage on these lines is relative to ground.
0 Volts and 120 Volts or 12,000 Volts and 12,120V look *exactly* the same to the device. Unless the surge is high enough to blow through the insulation of the devices enclosure and arc to ground it is absolutely irrelevant to the health of the device.
A house using two wire receptacles would be wired for pre-1990 earthing requirements. One need not ground wall receptacles to have superior surge protection. But earthing at the AC mains box must be upgraded to post 1990 code AND meet additional requirements defined in the previous post.
This proper earthing and a 'whole house' protector are less expensive, far more effective, AND enhances household human safety. All this without massive rewiring of a house for three wire receptacles. Notice a critically important parameter for surge protection. That earthing must be short (ie 'less than 10 feet'). What is necessary to install an effective 'whole house' protector? That household earthing must be upgraded to meet and to exceed post
1990 NEC code requirements. Superior protection regardless of two wire or three wire receptacles.
Meanwhile, too many homes do not even have earthing that meets those
1960 earthing requirements. Too many see lights working - then assume everything is just fine. One home even exploded because that missing earthing (and other factors) caused electricity to conduct through the gas meter.
The usual bullshit from w_ on plug-in surge suppressors.
The best information I have seen on surges and surge protection is at
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the title is "How to protect your house and its contents from lightning: IEEE guide for surge protection of equipment connected to AC power and communication circuits" published by the IEEE in 2005 (the IEEE is the dominant organization of electrical and electronic engineers in the US). (This link originally came from w_.)
A second god source is:
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this is the "NIST recommended practice guide: Surges Happen!: how to protect the appliances in your home" published by the National Institute of Standards and Technology (the US government agency formerly called the National Bureau of Standards) in 2001
Both guides were intended for wide distribution to the general public to explain surges and how to protect against them. The IEEE guide was targeted at people who have some (not much) technical background.
Common mode surges (H & N lift away from G) coming in on the power line are converted to transverse mode surges (H lifts away from N & G) by the N-G bond in US services.
Undersized is a "straw man". Plug-in protectors come in ratings from junk to very high.
Both the IEEE guide and NIST guide recognize plug-in suppresors as effective.
Amazing how religious beliefs about earth ground promote myths. The IEEE guide clearly describes plug-in surge protectors as primarily CLAMPING the voltage on all conductors to the common ground at the surge suppressor. The clamped voltage is safe for connected equipment. Earthing is secondary.
When you don't have technical arguments try pathetic scare tactics.
older model? power strips and specifically references the revised UL standard, effective 1998, that requires a thermal disconnect as a fix for overheating MOVs.
technology using series mode protection, which w_ says doesn't work.
None of these links say the damaged suppressor had a UL label. None of them say plug-in suppressors are not effective or that they should not be used or that there is a problem under the current UL standard. Problem fixed in 1998.
The religious mantra again. Not shared by the IEEE of NIST.
Religious mantra #3. And the NIST and IEEE say plug-in suppressors are effective.
Note "each type". Common mode surges do not come in past the N-G bond in the service. Plug-in suppressors have clamps from H-N, H-G, N-G and handle all modes anyway. And w_ has never provided specs for "each type of transient" for any of his favorite suppressors. Yet another stupid argument.
Religious mantra #4.
Bottom line - the IEEE and NIST recognize plug-in suppressors as effective.
I'm not sure of the terminology but the wiring appears to be two-wire, and not metal-clad.
I had the original 50-year-old service panel upgraded and a new ground rod installed. The cable and phone service is (now) properly grounded at the same point.
I think my current plan is to order a panel mounted protector like the Intermatic one, then try to have one outlet per room grounded, for point-of-use suppressors. Does that seem reasonable?
The same way a person that has no ground connection can plug his finger into the hot and not the neutral or ground contact in a socket and still get electrocuted. When you say the device has no ground connection, what you really mean is that it has no *obvious* ground connection.
And even if your device is a hundred million ohms from ground, it may be insulated from ground by something that will punch through when a 5,000 volt common-mode surge hits the device.
I already covered that in another reply. A device with no ground will be unaffected by a common mode surge up to the point of insulation breakdown through for example, the plastic case of the device, the wood table it's on, the carpeting under the table, etc. Basically a very close lightning strike which no affordable protection device will be able to protect against.
Static electric charges can build across shoes. Touch something such as a door or electronics. How does a circuit conduct electricity from finger to charges beneath those shoes? Many parts in that circuit are not conductive? But at those higher voltages, things not considered conduct become conductive.
Yes, an appliance without a better connection to earth will be less susceptible to damage. This is why some things are damaged whereas others are not. Even wall paint may become a conductor at these voltages. It is not possible to isolate an appliance from destructive transients. Otherwise lightning could not conduct through the best insulator - 3 miles of air.
Why does lightning strike a wooden church steeple? Wood is not a conductor? That is your reasoning. But wood is both a conductor and a connection to earth. Concrete is not a conductor according to your reasoning. But concrete is such a good conductor as to be recommended
- Ufer ground.
Protection has always been about earthing transients so that destructive paths are not found through appliances or through wooden church steeples.
You are assuming things not conductive when a building is chock full of conductive paths to earth. Just another reason why every high reliability building earths before transients enter a building. They know better. A transient permitted to electronics can find surprise paths to earth. Best protection which is also less expensive and easy to implement has always been to earth before a transient can enter a building. One properly earthed 'whole house' protector is that effective.
We are not protecting from close lightning strikes. Protection already inside appliances makes that irrelevant. We are protecting against a direct strike to AC mains down the strike which is a direct strike to every household appliance. Only some appliances destructively earth that direct strike. Which ones? You do not know. But that answer is irrelevant if the direct strike is earthed before it enters a building. Some utilities are earthed directly (cable TV and satellite dish). Others require a 'whole house' protector (AC electric and telephone). But that protection will only be as good as a single point earth ground.
Again, this was both a problem and solution well understood way back in the early 1900s. The technology so effective that your telco installed it on every phone line. Why would a telephone operator in a wooden room become a path to earth via non-conductive headphones and a wooden chair? Those become conductive paths to earth through her body. Why did that telephone operator not remove her headset when thunderstorms approached? Even long before WWII, single point earthing was well proven protection. The need for earthing has been that well understood for that long. Otherwise lightning could find a path to earth through that operator. If Pete C's reasoning was correct, the operator was never at risk. Telcos knew better. Even those non-conductive headphone and wooden chair could become a conductive and harmful path to earth.
Protecti> I already covered that in another reply. A device with no ground will be
Will a power strip protector somehow stops or block what three miles of sky could not? That is not what a power strip protector does. And yet that is why some daisy chain power strip protectors on a myth that more will create a chain of protection - stop or block a surge.
Meanwhile, every power strip must have a 15 amp circuit breaker so that excessive load does not concentrate on one power strip. Fires have killed because power strips were daisy chained when, instead, the solution was sufficient number of wall receptacles. Fire code in some larger cities did not permit power strips - same reason. Safer than a $25 surge protector power strip is the $3 power strip with an essential
15 amp circuit breaker. That circuit breaker to eliminate danger of too many loads on one wall plug. But you must confirm that breaker exists.
That breaker is not your primary safety device. Primary protection is to not daisy chain power strips. That breaker is only a secondary layer of protection. If you must daisy chain power strips, then the room needs more wall receptacles.
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