Surge protection without grounded plugs

My son just moved into an older house near his college. We're told that the electricity isn't entirely reliable and that he should use a surge protector.

The house's plugs aren't grounded. Will this affect the efficacy of a surge protector? Is the computer at risk or just the AC adapter?

Any recommendations would be appreciated.

TIA, David

Reply to
David Schwartz
Loading thread data ...

My son just moved into an older house near his college. We're told that the electricity isn't entirely reliable and that he should use a surge protector.

The house's plugs aren't grounded. Will this affect the efficacy of a surge protector? Is the computer at risk or just the AC adapter?

Any recommendations would be appreciated.

TIA, David

Reply to
David Schwartz

Hi, Dave. Surge protectors are supposed to work by absorbing the energy of voltage spikes caused by lightning and such. A typical surge protector will absorb the extra energy of the spike, and shunt the current to ground. That means they're not too useful without the GND pin on the plug.

But voltage spikes probably aren't the problem here. This sounds more like bad wiring, unbalanced loading of the pole transformer, or poor/ intermittent connections to the line neutral of the transformer. That will mean the line voltage at the plug may go way up or way down, depending on loading, humidity/condensation, the phase of the moon, or whatever. Surge protectors don't do anything about undervoltage, which can destroy a PC as easily as overvoltage. And if the voltage gets high enough, the surge protector will just be destroyed by sustained overvoltage.

I'd really suggest the house wiring get checked out by someone competent. After all, your kid is going to be living there.

Barring that, and assuming they've got working smoke detectors there (check yourself), a line conditioner might be a better choice for protecting the computer. A line conditioner is an autotransformer that senses the incoming line voltage, and switches taps (raising or lowering the voltage) to compensate. Since a college kid's computer is a mission-critical piece of equipment, the money will be well spent. For a standard computer and laptop setup, one like the TrippLite LC1200 should be sufficient. If the system's a laptop only, you can get away with less.

When you've got kids, there's no safety this side of the grave, I guess.

Good luck Chris

Reply to
Chris

It does no such thing at all.

A typical varistor based surge protector works by clamping the live to neutral voltage. Diverting current to ground is potentially hazardous.

Here's an example. Note that the ground simply passes through with no connection to the protection components. The one shown also has a gas discharge tube.

formatting link

Graham

Reply to
Eeyore

Here's another one that does not rely on the safety ground:

formatting link

There is some good info here:

formatting link
formatting link
formatting link
formatting link

If the two-prong outlets cannot be rewired, it might be a good idea to connect an external safety ground to the chassis of the computer or other appliance. A cold water pipe might be good enough, especially if it is copper. Otherwise a driven ground rod is pretty good. A UPS might be another option, especially if the power is noisy or intermittent. But the safest option is a properly installed electrical system.

Paul

Reply to
Paul E. Schoen

Myth purveyors will claim that a surge protector will absorb energy. Energy that could not be stopped even by three miles of sky. Protectors don't stop or absorb surges (except where myths are promoted). Protection means surges are earthed before entering the building. That energy must be dissipated somewhere. That somewhere is earth ground.

A protector is nothing more than a connecting device to protection. Protection is earth ground - where energy is absorbed. Essential is to have breaker box earthing upgraded to both meet and exceed post

1990 NEC code. That means an earthing electrode with a 'less than 10 foot' connection to the breaker box. Chances are the only earthing (if it still exists) was to a cold water pipe. That earthing is no longer sufficient even for human safety. For transistor safety, one 'whole house' protector connected to that upgraded earthing means massive transistor protection. Protection without rewiring the entire house.

Every incoming utility must enter at a same location to also make that short earthing connection. For example, the phone line has a 'whole house' protector installed for free by the telco. But that protector, also, is only as effective as its earth ground. Even the cable must be earthed to that same electrode before entering the building. Cable is protected without a protector. No reason for a cable protector. Cable is earthed directly with no protector. Again, what provides the protection? A box? No. Earthing is the protection.

What even makes a Franklin lightning rod effective? Sharp or blunt rod? Not relevant. Even a lightning rod is only as effective as its earth ground because earthing provides the protection.

Do not confuse safety ground in AC wall receptacles with earth ground. They are electrically different. That AC wall safety ground is for human safety. No surge protector will correct that missing safety ground. Far more useful on 'that' unreliable wiring is to replace selective circuit breakers with Arc fault breakers or GFCI breakers. Unreliable wiring is a human safety problem. A surge protector accomplishes zero. But again, read numeric specs for that surge protector. What does it actually claim to accomplish? Don't read its color glossy sales brochure. What do its numeric specs says it does?

It would help if you define which problem needs protection from AND to define "unreliable wiring". A breaker box GFCI circuit breaker goes a long way to protecting from unreliable wiring. An arc fault type is even better protection. The plug-in surge proetctor does nothing. It's own manufacturer will (quitely) recommend not using a power strip protector if receptacles are not three wire - a human safety threat created by connecting a three prong power strip to a two prong outlet.

Surge protectors are only connecting devices to protection. That protection is earth ground. If too far away from earth ground, a surge proetctor must shunt somewhere. It may shunt (connect, divert, clamp) a surge to earth via the computer. The effective protector earths before surges can enter the building. A surge properly earthed will not be inside the building to overwhelm protection already inside all appliances. All appliances contain any protection that would work on its power cord. Internal protection that may be overwhelm if the rare and destructive surge is not earthed BEFORE entering the building.

Reply to
w_tom

Please do not cite HowStuffWorks as honest or accurate. It even contradicts what your other citations say. It is so full of outright lies and myths that this criticism only address the errors from a first few pages:

Experience with household appliances exposes those myths - described in: "Computer problem need help" posted on 1 Aug 2002:

formatting link

Reply to
w_tom

I agree that "How stuff works" is not the best, but motor loads can and do create power surges. The surge may appear on the same phase as the load, due to inductive "kick", but also the starting current in one phase can cause enough voltage drop through the neutral to produce a higher voltage in the opposite phase. If the neutral line is damaged or improperly connected, the two 120V legs may be unbalanced depending on the individual loads.

Paul

Reply to
Paul E. Schoen

As I'm not an electrician (that should be obvious from my initial post), I admit to having a hard time sifting through all of this stuff. My take is that:

- a plug-in surge protector of any type won't protect my son's computer

- what is required is for the entire house to be surge protected before the power enters the house.

Are these the correct conclusions?

TIA, David

Reply to
David Schwartz

There are several kinds of power problems, and each one has certain risks and means of protection.

A surge protector for the entire house, at the service entrance, is probably the best, because it deals with the surge before it enters the rest of the wiring. But it is expensive and requires an electrician to install it.

Properly installed and grounded wiring is very important, for the safety of humans as well as equipment. It would be worthwhile to rewire the circuit that feeds the computer, or even run a new line, if possible. Depending on the age of the house, it's possible that the wiring could be aluminum, which often develops poor connections, and can cause all sorts of problems, including fire.

Surges from lightning are the most serious, and it is difficult to achieve

100% protection. The best method is to unplug the computer, and remove any phone lines or other external connections. I have even had computer speakers damaged by a close lightning strike that also damaged my modem.

Plug-in surge protectors offer some level of protection. I have a surge protector and a UPS on my computer, and they probably helped, but the main surge probably came in through the phone line, which was actually damaged and required a repair to the cable from the pole to the house.

I have pictures of the damage caused by the lightning. It apparently came down the wet bark of a huge sycamore tree, and then arced to the phone line as well as the power lines (and blew open the neutral):

formatting link

Paul

Reply to
Paul E. Schoen

From WHAT ? Gremlins ? Why do you think that ?

It all depends what level of protection you want.

Graham

Reply to
Eeyore

You don't have any clue what your talking about? Really, be honest!

The earth ground is only there for a direct ground reference and a low resistance path to ground.

The problem with neutral and hot is that if they are wired incorrectly they can easily kill someone. By having a direct reference to ground you can eliminate this if it is used properly. It also supplies a lower resistance to ground than the neutral(atleast as far as I have seen in my own house).

But in any case an earth ground an a neutral are identical in most cases except for some small potential difference(atleast they should be in any properly wired home).

I suggest you read up on

formatting link

As far as surges go, you have essentially varistors that provide a very low resistance path for a high voltage spike. This essentially takes out the load after the varistor preventing(hopefully) most of the current from going through the load.

For example, if you have

Hot -------+---- Load---+ | | Varistor | | | Neutral ---+------------+

And if a large voltage spike occurs then the varistor acts somewhat as a short essentially resulting in a short from hot to neutral and therefor essentially dissconnecting the load from the mains. (atleast in theory it would do that)

This has nothing to do with ground and you could even tie the varistor from ground to netural(although it would not work if the ground was cut).

The varistor only stops surges though and doesn't protect in other others. If the varistor breaks then so do the surge protection.

In any case "surge" protection doesn't need ground as netural is suppose to be approximately equivilent to ground. The reason for "earth ground" in a plug is for safety reasons and not surge protection.

Its a fact that neutral must also exist to complete the circuit so you can always get surge protection... its also true that simple surge protectors are not all that great. Using a simple MOV doesn't protect the load all that great but its better than nothing and can't hurt.

So if the OP is only concerned with surge protection then he can do that by buying good surge protectors... having earth ground isn't going to have any effect except it could potentially make the surge protector a little better if it was designed to use it. Maybe it could use a something like

  • -----+ / \ MOV1 MOV2 / \

- -+--MOV3-+--GND

Where if the ground was hooked up properly then you'll have better surge protection... but there are better methods.

The extra earth on plugs is only for safety.

Reply to
Jon Slaughter

No. You don't know if the "unreliability" you heard about has to do with surges or not. Suppose, for example, that "unreliability" means there are frequent power outages. All the surge protection in the world won't address that problem.

If you want to use surge protectors, the IEEE recommends that you use both whole house and point of use protectors.

Ed

Reply to
ehsjr

As others have noted, the problem may be surges or may be other power problems. How common are lightning storms?

The best information on surges and surge protection I have seen is at:

formatting link

- "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). And also:

formatting link

- "NIST recommended practice guide: Surges Happen!: how to protect the appliances in your home" published by the US National Institute of Standards and Technology in 2001

The IEEE guide is aimed at those with some technical background. The NIST guide is aimed at the unwashed masses.

The IEEE guide explains plug-in suppressors work by CLAMPING the voltage on all wires (signal and power) to the common ground at the suppressor. Plug-in suppressors do not work primarily by earthing (or stopping or absorbing). The guide explains earthing occurs elsewhere. (Read the guide starting pdf page 40). In the US, UL requires plug-in suppressors have MOVs from H-G, N-G, H-N.

Note that all interconnected equipment needs to be connected to the same plug-in suppressor, or interconnecting wires need to go through the suppressor. External connections, like phone, also need to go through the suppressor. Connecting all wiring through the suppressor prevents damaging voltages between power and signal wires. These multiport suppressors are described in both guides.

w_ has a religious belief (immune from challenge) that surge protection must use earthing. Thus in his view plug-in suppressors (which are not well earthed) can not possibly work. As the IEEE guide explains, plug-in suppressors do not work primarily by earthing.

Complete nonsense. Water pipes (10 ft or more buried metal) have had to be used as an earthing electrode in the US for a very long time.

A service panel suppressor is a good idea but then you also need a short connecting wire from phone and cable entry protectors to the earthing wire at the power service.

The house is likely rented which probably makes a power service panel suppressor impractical.

The cable and phone building entry protectors must connect with a

*short* wire to the earth electrode wire at the power service. A short wire keeps the potential at the power and phone and cable ?grounds? the same. In the IEEE example the ?ground? wire from the cable entry protector is too long. That allows 10,000V to develop between the cable and power wires. The IEEE guide says in that case "the only effective way of protecting the equipment is to use a multiport protector." The IEEE guide says even 10 foot connecting wire is too long (pdf page 38).

Francois Martzloff, the NIST guru on surges and author of the NIST guide, has written "the impedance of the grounding system to `true earth' is far less important than the integrity of the bonding of the various parts of the grounding system."

According to NIST guide, US insurance information indicates equipment most frequently damaged by lightning is computers with a modem connection TVs, VCRs and similar equipment (presumably with cable TV connections). All can be damaged by high voltages between power and signal wires.

No reason for a protector? The IEEE guide notes that the voltage between cable center conductor and sheath is limited by the breakdown of F-connectors which is typically 2-4,000V. The guide notes that connected equipment can be damaged at those voltages. Plug-in suppressors are likely to clamp the voltage to a safe level.

If the wiring to the outlets does not have a ground, in the US equipment with a ground prong on the power cord can be plugged into a GFCI outlet or outlet that is protected by a GFCI. (The outlet needs to be marked ?No equipment ground?)

The best solution is if the computer can be moved to where there is a grounded outlet. Using a plug-in suppressor without a grounded outlet is not a great idea. Particularly if the equipment plugs have ground pins there is not a great solution.

If the plugs are all 2 prong, I would probably use a plug?in suppressor.

A plug-in suppressor provides protection without a ground wire, but as the IEEE guide shows, the ground potential can be shifted when the suppressor works. It could also shift the ground potential if the MOVs get ?leaky? if hit with many surges.

-- bud--

Reply to
bud--

Indeed. The house wiring itself won't cause any surges.

From what I've heard the OP would be wise to check that the neutral isn't 'floating' though (assuming this is in the USA with the '2 phase' 240V supply).

Graham

Reply to
Eeyore

Points are correct IF surges are the problem. But surges have nothing to do with unreliable wiring. Surges are sourced externally. Unreliable wiring is an internal problem.

Also irrelevant are surges from household appliances such as motors. If those were destructive, then everyone here is trooping daily to the hardware store to replace clock radios and dimmer switches. Protection already inside all appliances makes those motor 'surges' completely irrelevant.

Unreliable wiring would create problems such as power loss, fire, or repeated circuit breaker tripping. Those internally generated events are different externally sourced events such as surges. One symptom of unreliable wiring is extension cords - a common source of fire and why Arc Fault circuit breakers are now required for bedroom circuits. Ground fault breakers are a solution for circuits that are only two wire - do not have the safety ground wire. Also a threat are multiple outlet connectors (such as power strips) that do not have the 15 amp circuit breaker.

As noted repeatedly (and why HowStuffWorks is so embarrassing), all appliances contain internal protection. Computers are particularly robust. Protection for all appliances means earthing anything so massive as to cause failures. Surges that may overwhelm protection inside electronic appliances must be earthed before entering the building. Those destructive surges typically occur once every seven years - a number that varies significantly even within the same town. We earth 'whole house' protection for that rare event.

Again, every incoming utility wire must be earthed. Telco 'installed for free' protector must connect each phone wire to same earth ground used by AC electric and cable TV. Destructive type of surge seeks earth ground. It is not stopped or absorbed. It must be diverted or shunted to earth. A little one inch part inside a 'magic box' does not even claim to stop or absorb what three miles of sky could not. Connect every incoming wire inside every cable to earth ground either directly (cable TV, satellite dish) or via a protector (AC electric, telephone).

Reply to
w_tom

Points are correct IF surges are the problem. But surges have nothing to do with unreliable wiring. Surges are sourced externally. Unreliable wiring is an internal problem.

Also irrelevant are surges from household appliances such as motors. If those were destructive, then everyone here is trooping daily to the hardware store to replace clock radios and dimmer switches. Protection already inside all appliances makes those motor 'surges' completely irrelevant.

Unreliable wiring would create problems such as power loss, fire, or repeated circuit breaker tripping. Those internally generated events are different externally sourced events such as surges. One symptom of unreliable wiring is extension cords - a common source of fire and why Arc Fault circuit breakers are now required for bedroom circuits. Ground fault breakers are a solution for circuits that are only two wire - do not have the safety ground wire. Also a threat are multiple outlet connectors (such as power strips) that do not have the 15 amp circuit breaker.

As noted repeatedly (and why HowStuffWorks is so embarrassing), all appliances contain internal protection. Computers are particularly robust. Protection for all appliances means earthing anything so massive as to cause failures. Surges that may overwhelm protection inside electronic appliances must be earthed before entering the building. Those destructive surges typically occur once every seven years - a number that varies significantly even within the same town. We earth 'whole house' protection for that rare event.

Again, every incoming utility wire must be earthed. Telco 'installed for free' protector must connect each phone wire to same earth ground used by AC electric and cable TV. Destructive type of surge seeks earth ground. It is not stopped or absorbed. It must be diverted or shunted to earth. A little one inch part inside a 'magic box' does not even claim to stop or absorb what three miles of sky could not. Connect every incoming wire inside every cable to earth ground either directly (cable TV, satellite dish) or via a protector (AC electric, telephone).

Reply to
w_tom

So what does the typically destructive surge seek? Earth ground. Why must those earthing wires be so short? Well let's finish the math. An AC wall receptacle is maybe 50 feet from the breaker box. IOW it is maybe 0.2 ohms resistance. But the same wire is something like 130 ohms impedance to the surge. What happens when a power strip protector attempts to earth a trivial 100 amp surge via neutral wire?

13.000 volts difference. Will a surge use the 13,000 volt wire to obtain earth? Of course not. It will also find other path to earth via furniture, wall paint, baseboard heater, etc. The AC receptacle ground is safety ground. But the destructive surge, if permitted at the appliance, will find every path to earth - destructively.

The effective protector earths before that surge gets anywhere near to appliances.

Your MOVs protectors do protect from the type of surge as exampled. Do appreciate that it is not the type of surge that typically causes damage. Surge that damaged electronics seeks earth ground. Its energy must be dissipated somewhere. If not dissipated in earth, then it dissipates destructively via household appliances in a path to earth. If the MOV protector is grossly undersized as is common with many plug-in protectors, then even these scary pictures can result:

formatting link
formatting link
formatting link
formatting link
formatting link
or
formatting link

I appreciate the spirit of your reply. But you have completely ignored some critical facts. Typically destructive surge seeks earth ground. It may be completely ignored by your three MOV protector. Or your three MOV protector may even give the surge more paths to find earth, destructively, via adjacent appliances.

The surge you have discussed is typically made irrelevant by protection already inside appliances. Anything that a power cord protector might accomplish is already inside appliances. What can overwhelm protection inside appliances? A type of surge that seeks earth ground. We earth this typically destructive surge before it can enter the building - and with only one properly sized protector. Then massive energy of this far more destructive surge is dissipated in earth - does not find destructive paths to earth via household appliances.

What provided the protection? What dissipates surge energy? Does that silly little MOV absorb such surges? Of course not. Surge energy must dissipate somewhere. Earth is where surge energy is dissipated. No earth ground means no effective protection from a type of surge that typically cause appliance damage.

Appreciate that I have understood earthing for probably longer than you have existed. You are even confusing low resistance earthing with low impedance. Appreciate why a connection to earth ground must be 'less than 10 feet' - and other critical factors. If you don't understand those numbers, then you have not yet learned the many functions performed by earthing.

Of course this is well bey> You don't have any clue what your talking about? Really, be honest!

Reply to
w_tom

formatting link

I guess your the god of earth ground? Please... nots not get into some silly fight over such an issue. I believe you are confusing safety with surge protection. Surge protectors are not decides with saftey in mind but only to protect the equipment involved to some degree.

I agree that safety is an issue and I agree its best to have earth ground. Hell, maybe they would put a piece of rebar driven into the ground where every recepticle is along with some type of external surge protection for the whole house? But the fact of the matter is that is that many devices use only hot and netural without any earth ground even whe its available(go look at your toster and any small appliance).

In any case my point is that surge protectors themselfs do not need earth ground. I never said it was a good idea not to have them but you claimed they are completely ineffective without earth ground and this is simply not the case. They do exactly what they were designed to do with out any earth ground... infact if you open one up, at least in a cheap one, you will not see the surge protection circuitry use earth ground at all.

The only thing I really disagree with you on is that surge protectors, and here I'm implicitly refering to the common ones that the average person can buy, do not need earth ground to protect against your average surge and minimize damage to the device connected. It greatly minimizes the damage to devices connected compared to not having anything at all(Even if you have earth ground).

Is it the ultimate solution? Can you stop all surges and prevent all possible saftey hazzards? No. But you can increase your chances to device failure by 1000x(I'm just making that number up but seems resonable) by adding even a cheap surge protector(a simple mov). Of course even that introduces some saftey issues as you have proven by your links... MOV's are perfect and if they short out then you can have a serious saftey problem.

Anyways...

Reply to
Jon Slaughter

What SURGE ?

A voltage transient across live and neutral 'seeks' nothing.

There seems to be some huge myths about 'surges'.

Graham

Reply to
Eeyore

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.