TVSS effectiveness?

[Tetra]

I've installed hundreds of TVSS's (transient Voltage Surge Suppressors) and always thought of them as en effective safety measure, but recently I've had a few electrician buddies of mine claim that they aren't all that effective, that a lot of times they are simply a waste of money?

I was wondering how you guys felt about this topic, see some opinions on their effectiveness, around here the power company has a program where they come out and put them in for $5 extra a month and I frequently recommend to my clients to go for it and that it's a good idea, is it?

 

[Volta]

Better than nothing.

There's no way to fully stop damage from lightning or utility surges, but having one or hopefully more points in the system where the voltage can be clamped down can really limit the effects.

When possible, it's great, IMO, to have one at the meter base, one at the receptacle, and even a surge strip, depending on what you want to protect.

 

[SG-1]

I think they are a good idea if you use the layered approach. One at the service is supposed to protect from incoming surges. Within the house many appliances produce their own transients. The smaller secondary units that plug into the receptacles may lessen the effects of these. I have the secondary units plugged into nearly every receptacle that has an appliance or electronic load.

I also have three of the 70KA service type spread around on my detached buildings that have a panel. It seems to me that I have lost less electronics ( I cannot think of any at the moment ) & no more well pumps ( $ 2000 per shot ) in the years since.

I believe they are worth the investment :happyyes:.

 

[kbsparky]

Many have marketed these devices over the years. The problems come later -- when the devices fail to properly "protect" the connected utilization equipment, and the customer comes after YOU for selling him a bill of goods.

Don't matter whether you're right or wrong at this point, you are now in the position of defending yourself against hostile customers.

For that reason, I will install these devices IF the customer asks me to, but I do not engage in actively pushing or selling them up front.

Even many power companies have discontinued promoting these devices after having to pay out more in claims than they took in with those monthly fees....

 

[kbsparky]

....I believe they are worth the investment ....

I would not call this an "investment" ... but would label them an "Expense"

 

[Tetra]

I would not call this an "investment" ... but would label them an "Expense"

But why?

The whole approach to this post was to find out the reasoning behind that thinking

Honestly I think like Volta and SG-1 when it comes to this subject at the moment.. But I bet Electricians in the 60's or 70's thought aluminum 12/2 was the greatest invention since sliced bread, and look how that turned out. I just don't want to be recommending this to people if it is truly useless, which is why i want to hear your guys's arguments for and against em.

 

[Volta]

From the fairly limited research I have done, I think a single large MOV per conductor set is much better that multiple small varistors in parallel, but otherwise it is very hard to compare units due to a lack of standardized sales points.

The number of joules is the most easily spotted info on most descriptions, but without a reference to the time duration needed to absorb that amount of energy that alone tells us little.

 

[kbsparky]

Investment vs Expense

Investment vs Expense

But why?....

With an investment I expect the value to increase over time, and provide a reasonable return. An expense is an outlay of cash, the best scenario I can hope for is to avoid more outlays of cash, but there will not be any increased value, nor return on investment.

A surge unit is by design a suicidal device which sacrifices itself to preserve others connected on the system. The value of it decreases each time it absorbs a surge. Eventually, it will wear out and need replacing, resulting in more expenses.

One could argue that the expense of a TVSS unit acts as a back-door investment ... that avoiding more expenses by its presence could be deemed an investment of sorts.

I don't buy that line of thinking.

Same thing as buying a car or work vehicle. The dealer will call it an investment. In reality, it's a big expense. Depreciation hits you big time as soon as you drive it off the lot.

 

[ELA]

I've installed hundreds of TVSS's (transient Voltage Surge Suppressors) and always thought of them as en effective safety measure, but recently I've had a few electrician buddies of mine claim that they aren't all that effective, that a lot of times they are simply a waste of money?

Ask your buddies why they are not effective? How do they "know" that circuit breakers are effective?
One way is to test them. You apply an overcurrent to a breaker and it trips.

The problem with TVSS's is that it is a little more complicated for the individual to test them. They are tested by manufacturers all the time.
Transients of varying amplitudes are applied to a device under test. It can be demonstrated that the device will either experience a temporary malfunction, or in some cases a destructive failure.

TVSS's are now added to the design and retested. The device now withstands thousands of transient applications with no malfunctions.
This provides the proof of their effectiveness.
I have performed this type of testing on many different products.

There is no doubt that TVSS's will be very effective if correctly applied.
If they are incorrectly applied they may not be as effective.

Whether or not it is worth it to invest in a whole house TVSS is another matter. One can certainly question how often, and of what amplitude, transients might be occurring at a certain location to warrant the need.
This can also be tested as a justification for installation.

 

[SG-1]

I would not call this an "investment" ... but would label them an "Expense"

The term "investment" may not be the best, maybe minimax strategy describes it better.

For the plug-in wall units:

Corporation XX will repair or replace this unit for as long as you own it.

$50,000 dollar protection plan for connected equipment.

$75,000 for the whole house unit.

Units have LED indicator lights to show they are still alive.

 

[ed downey]

I would definitely say they are worth the expense.

When I built a new house (8) years ago during the first year I lost (3) Network cards and a mother board in my computer and a cordless phone.

I installed a TVSS on the main service panel and then another on the incoming cable TV & one on the incoming Phone line.

Since I installed these three I have not had an issue with any electronics in the last (7) years.

-Ed

 

[petersonra]

My suspicion is that the power strip type surge suppressors are not especially helpful. Most modern electronic equipment is just not susceptible to damage from the very limited amount of energy the strip type suppressors can absorb.

In most cases, I also suspect that whatever surges come from within an electrical system (especially in a residence) are unlikely to damage much of anything, so i would concentrate on surges coming from outside.

I just don't know if whatever surges the service type units can absorb are worth the cost. I don't think anyone really knows with any certainty. I don't think they will hurt anything, but whether they are helpful is up in the air in my mind, especially with modern electrical and electronic equipment.

I also question the use of N-G and L-G suppression in the strip type units. I just don't see how that is helpful and it might have some potential for negative impact on your stuff.

 

[SG-1]

I had a battery powered indoor/outdoor thermometer destroyed by a thunderstorm. Lightning induced a transient on the outdoor probe wire, unless anyone has a better idea.

I supect lightning can induce transients on wire runs inside homes.

Have had electric fence chargers blown apart, the stepup transformer was found 6 feet from the unit in one instance.

 

[petersonra]

I had a battery powered indoor/outdoor thermometer destroyed by a thunderstorm. Lightning induced a transient on the outdoor probe wire, unless anyone has a better idea.

What do you mean by induced? It is also possible the thing just failed. or it could have been static electricity.

I supect lightning can induce transients on wire runs inside homes.

I think it far more likely that such things come from the outside in.

Have had electric fence chargers blown apart, the stepup transformer was found 6 feet from the unit in one instance.

Sounds more like a direct strike. I don't know that any kind of surge suppressor will protect against a direct strike.

 

[ELA]

My suspicion is that the power strip type surge suppressors are not especially helpful. Most modern electronic equipment is just not susceptible to damage from the very limited amount of energy the strip type suppressors can absorb.

Your suspicion?
Most modern equipment that is AC line connected has an Internal Surge suppression device due to the fact that they are so susceptible to upsets and possible damage from Transients and surges.

In most cases, I also suspect that whatever surges come from within an electrical system (especially in a residence) are unlikely to damage much of anything, so i would concentrate on surges coming from outside.

A person can build a setup with a bunch of oscillating relays that will upset all kinds of equipment (without protection) due to their transient generation . It was one of the early Nema standard noise tests called the ANSI C37.90a-1974 SWC Level C Chattering Relay Test.

It is not only about possible damage but also reliability, (up time), etc.

I also question the use of N-G and L-G suppression in the strip type units. I just don't see how that is helpful and it might have some potential for negative impact on your stuff.

Do you not believe in common mode interference? While transients entering at the service may be differential initially they can become common mode after some distance downstream from the bonding point.
There are standards that dictate testing against both differential mode as well as common mode interference. If the device under test has only differential mode protection it will fail miserably.

So even if you do not believe that common mode interference can be hurtful a person wanting to pass certain UL and other standards has no choice but to include differential mode protection.

 

[petersonra]

Your suspicion?
Most modern equipment that is AC line connected has an Internal Surge suppression device due to the fact that they are so susceptible to upsets and possible damage from Transients and surges.
Which is one reason they are far less susceptible to such problems than similar equipment was in the past.


A person can build a setup with a bunch of oscillating relays that will upset all kinds of equipment (without protection) due to their transient generation . It was one of the early Nema standard noise tests called the ANSI C37.90a-1974 SWC Level C Chattering Relay Test.
Why would I build such a thing and run it in my house? Most residences, which is what I specially limited my comments to, just do not have much in the way of internally generated surges.
It is not only about possible damage but also reliability, (up time), etc.
You are making an assumption that adding surge protection to the average residence will have a positive effect. Do you have any actual evidence to support that assertion?

Do you not believe in common mode interference? While transients entering at the service may be differential initially they can become common mode after some distance downstream from the bonding point.
There are standards that dictate testing against both differential mode as well as common mode interference. If the device under test has only differential mode protection it will fail miserably.

So even if you do not believe that common mode interference can be hurtful a person wanting to pass certain UL and other standards has no choice but to include differential mode protection.
I don't believe common mode interference at devices inside a residence are anywhere near the problem that the standards or the marketing hype might tend to indicate that it is, and adding something to deal with it in surge strips may actually do more harm then good. The place to stop the transients is at the service point. Then you won't have to worry about them becoming common mode, if that is really an issue. I don't care if the standards require it or not. Codes often require things of dubious benefit - think AFCIs.

JMNSHO. Take it for what it is.

 

[ELA]

It is not only about possible damage but also reliability, (up time), etc.

JMNSHO. Take it for what it is.

You are making an assumption that adding surge protection to the average residence will have a positive effect. Do you have any actual evidence to support that assertion?

I don't care if the standards require it or not.

Taken as being your Opinion only.


I have years of EMI testing experience to back what I state to be true. Along with nearly every manufacturer of AC line connected equipment that incorporates surge protection into their devices knowing the reliability increase they can provide.

 

[SG-1]

What do you mean by induced? It is also possible the thing just failed. or it could have been static electricity.

Induction principal, lighting does not have to strike a line to cause current to flow in it. When units like this fail they go blank, this units display was frozen. The LCD display was crazy. I pulled the batteries & let it set for 24 hours. It came back up just as goofy. It was observed to be operating properly before the storm & goofy immediately after the storm.



I think it far more likely that such things come from the outside in.

Never said that was not true, only they can come from within.


Sounds more like a direct strike. I don't know that any kind of surge suppressor will protect against a direct strike.

A direct strike would have damaged the barn. This happened to several units. A KTK-R fuse was blow apart during one storm. Only found half of it. It was added upstream of the fence charger.

I do say that a properly installed GES is essential when dealing with transients. I did not have one and did not know it, until I got to digging around.

 

[T.M.Haja Sahib]

A main factor in the failure of a TVSS to protect is its lengthy earth lead.The surge voltage across this lead during its operation applies to the device the TVSS is intended to protect with disastrous consequences.So one clue in the effective usage of a TVSS is to keep its earth lead as short as possible.

 

[Volta]

A main factor in the failure of a TVSS to protect is its lengthy earth lead.The surge voltage across this lead during its operation applies to the device the TVSS is intended to protect with disastrous consequences.So one clue in the effective usage of a TVSS is to keep its earth lead as short as possible.

Yes, and also the leads from the electrical system to the TVSS device.