Residential AC Surge Protection Using SPD’s and TVSS’s

May 31, 2009

lightningNeither the IEEE (Institute for Electrical and Electronic Engineers) or ANSI (American National Standards Institute) recognize Joule Rating as a means to determine any level of surge protection.

The best way to deal with electrical surges and spikes is to divert them from entering the house in the first place. This is why the external ground system mentioned in Part II is so important. Spikes and surges look for the quickest and shortest path to ground.  Industry Standards recognize that creating a tiered or layered approach to transient voltage  management for your house will provide the best protection, but it’s still no guarantee. Lightning strikes and surges can appear to have their own mind when it comes to seeking ground.  Following the recommendations that I have mentioned in this series of articles will assist in properly protecting  you and your house.

Layered Approach to Surge Suppression

Approaching  surge protection with tiers serves to create layers of  filtering .  ANSI and IEEE acknowledge 3 tiers, A, B and C.  Each level is recognized to provide protection for a defined application. Look at the following drawing to visualize the different tiers and location of the protection device. Class C is located at the service entrance or meter, Class B serves sub-panels and points of distribution (power strips), and Class A provides protection at the source or point of use (POU).

 TVSSv2

Most whole house residential grade TVSS’s  (transient voltage surge suppressor) use MOV’s (metal oxide varistors) for protection. By design, the TVSS does not absorb the fault but divert it to ground. By doing so, these faults erode the MOV’s over time. For this reason, most high quality TVSS’s include some form of “wellness” indicator or failure alarm (red or green LED lamp). Once the MOV’s are destroyed, the lamp indicator is extinguished or in some cases sets off an alarm. Studies show these MOV equipped TVSS’s can last up to 10 years. Granted, this life expectancy is directly impacted by the number of spikes and surges diverted by the MOV’s. So if you live near me in Texas, Oklahoma or places with lots of lightning, don’t count on the 10 years of life. 

The IEEE  recognizes three classes of surge protection and they all perform a defined task, but regardless of the class, all the surge protectors should meet these standards.

  • Listed  with UL 1449 Second addition (not meets, complies or designed to). TIP: If a product is “listed” with UL, Underwriters Labratory actully tested it for compliance to the standard.
  • Comply with ANSI/IEEE C62.41 as it pertains to the class category (C, B or A)
  • SVR rating of 400V or less (probably the most important rating)
  • Per phase rating of 70,000A or less
  • TVSS shall protect against line to line, line to ground  and neutral to ground voltage transients
  • Include visual indicators (red or green LED) for proper operation or failure of the TVSS
  • Class C & B devices shall operate bi-directional and treat both positive and negative impulses, yielding line control and short fliker ride-through. If the Class A does this that’s good too, but more important in the Class B and C
  • In shopping for a TVSS (aka SPD or Surge Protection Device) look for this information on the box or possibly in the fine print with the instructions.

    Surge Protection Devices come in many shapes and sizes at each class allowing you different choices. If you choose to install a Class C unit, you may have to employe an electrician, otherwise  you can use plug-in modules for the other two levels. 

    Class C Whole House TVSS Suppressors for Service Entrance Applications: Intended to be located at the incoming AC service or AC service panel. For various reasons, there are multiple types and styles for Class C residential TVSS’s. Hopefully one of these styles can be integrated into you electrical system.

    8MLB34CAXTULUCCA683WXWCAZ9RMICCAAJD0LLCA2TBUMZCAJP70R2CAQBLV90CAXW8Z0KCAD3SO8UCAWLMVA8CAW85X0MCA09XOTYCAIKMTBACAXK0BG6CAGJA7AICA11C7C0CAZRGZN5CASXME2QMeter Base TVSS: In some municipalities the utility carrier may offer to sell or lease you this type of TVSS. Other than the fact they will probably want to charge you a monthly fee, I like the meter base style. This TVSS is placed in the circuit prior to entering the house service panel. This allows the TVSS to divert any external surge to ground prior to entering the AC Service Panel where a surge could go through the house instead of the intended ground source.   I spoke with my electric provider but they did not offer this service nor would they allow me to supply my own.

     Circuit Breaker Derived TVSS: With this design, the TVSS is wired into the house AC Service panel. Like most, it is equipped KGXLCICAK8YY0ACA4Y6SENCAT00S0QCA8ILWGGCAI4RG93CAPL7N6JCAIOLQEOCA89V8DICADV5D7SCAFP6C2ZCA6SSVLQCACWP20OCA0IU2YTCARFBJFUCAW6A4B2CABBYFDICAZGFPHTCAIU4OGSwith MOV’s and a state of health LED lamps. These styles can be purchased for both indoor and outdoor applications (indoor model pictured). The key here is to keep the TVSS installation as close as possible to the service panel and the connection wire should be as with the short as possible (6″ or less). For my house I also re-arranged my circuit breakers in the panel to allow me to place the TVSS circuit breakers as close to the incoming mains as possible. This is just a little added work to divert the surge as soon as it enters the panel. 

    QO Breaker TVSSAC Panel Based TVSS: Similar to the circuit breaker design previously mentioned. This breaker style TVSS consumes 2 breaker positions to provide panel protection. The advantage of this type is that it connects directly to the bus terminations in the AC Service panel. The disadvantage is that it consumes two positions and you may not be able to locate one that fits your AC service panel. 

    Power StripClass B  TVSS Suppressors for Distribution and Short Branch Circuits: As a classification the “B” type is recognized to serve electrical sub-panels and distribution, meaning a power strip with multiple outlet with a collection of devices to protect.   The Class B is the most common type found in electronics, computer stores and home centers. You will have numerous to choose from. Just remember to use the criteria listed above to  help with your choice. I would not use the joules rating as part of your decision making process.  Belkin surge protector

      Class A TVSS Point of Use Surge Protection Device for Outlet and Long Branch Circuits:  As a Class A TVSS, this device can either be an individual plug-in module (as pictured) or the outlet itself. I have used both and depending on the application the outlet version can be a better choice when you have limited space, such as behind a refrigerator or Plasma TV. Additionally, I found the outlet style more difficult to obtain and more than double the cost of the plug-in style. They both include the proper operation indicator. 

     By this point you should recognize two major points. 1)  Having proper grounding is imperative and, 2) surge suppression goes beyond point of use (POU) devices, 3) implementing a tiered approach is necessary to protect you and your household adequately. 

    Believe it or not…. there is still more. Next time I will discuss specific surge protection for your CATV and Telephone service.

    You may also want to read: Electrical Switches and Outlets, AC Service Ground and Bonding, AC Service Ground Part II,

    Advertisements

    AC Service Ground and Bonding Connections Part II

    May 17, 2009

    electricalLightning is responsible for more than $5 billion in total insurance industry losses annually, according to Hartford Insurance Company.

      Here in the Southwest the weather is struggling between winter and spring which brings heavy rains and torrential thunderstorms. These conditions increase the opportunity for electrical surges and spikes. The impact of these storms can cause both personal and property damage. Proper grounding and surge protection can  be your best defense.

    Unplugging electronic devices was the old school method of protecting our electronics, however with more microprocessor based equipment that may be built-in or hardwired it becomes difficult to do that.  This can be good and bad. On the good side, this “smart” technology can allow our washing machines to weigh the clothes to determine how much water to use, to our sprinkler systems determining how moist the soil is before it waters our landscape. On the bad side, all of these electronic devices are highly susceptible to the negative effect of power surges and spikes. Any technology less than 10 years old can easily be a candidate for failure due to technological advances based on micro-processor based technology. With all that said, it becomes very important to protect all of these devices from electrical surges and spikes. Even if you live in an area with very little lightening, or thunderstorms, your equipment is still subject to utility and equipment based electrical surges. 

    Even though most of us recognize electrical surges as they occur from outside sources, (severe storms, etc.) power fluctuations (or spikes)  from utility switching equipment and even equipment within our house have the ability to create power transients that can have an impact.  So, to properly protect you and your house, you may consider going beyond the typical power strip or point of use (POU) surge protector by having multiple layers of protection.  Obviously, equipment such as a Flat Panel TV, computer or audio equipment require point of use (POU) surge protectors but including  Surge Protection at the point of entry (electrical service panel) will also provide protection for items such as dishwashers, HVAC systems, microwave ovens, washers, dryers and so on.    

    tt43kicamiqr72cajlxf3qcaqg2uy9cataa1tgcaozp5xycal1ce1jcanvsd5ycaf7gwszca1aq9vncaubtid9cayql0nrcav7a5t3ca26lasucaabxmn3ca179qr3cagr0p6uca5rqldfca8ochrrProper surge protection cannot be discussed without stressing the importance of  a grounding network for your house. My article on bonding & grounding covers how to identify and inspect your system, but the subject warrants a bit more discussion. The reality of the situation is that your household experiences electrical spikes and surges regularly even without a storm in sight and the source can be any incoming services (Commercial AC, CATV, Satellite TV and Telephone Service) as well as electrical appliances in your house. 

    Both the National Electric Code (NEC) and National Institute of Standards recognize the importance of proper grounding  by providing recommendations and standards to increase this level of protection. Read the following articles before you go too much further. For your house to be properly protected, the integrity of the complete house is essential. Bonding and Grounding, Electrical Switches and Outlets (especially testing of the outlets). TIP:  Any outlet without proper grounding should not be used for any electrical equipment that requires protection even when you have a POU surge protector plugged in.

    Ensure your grounding systems is up to par:

    1. Test all your outlets as mentioned above.
    2. If your house is over 30 years old and the electrical service has never been upgraded, the water pipe may be the only source of ground. Adding a ground rod would be a good idea at this point. Add the ground rod near the electrical service meter and a new wire between the rod and the ground termination bar in the service panel. It’s okay to leave the cold water pipe connection in tack. The grounding schematic  found below is considered a perfect world design. Creating this form of grounding arrangement will optimize your ground system.
    3. Grounding SchematicIf you have a ground rod and it is over 20 years old, it may be time add a new one. Underwriters Laboratory (UL) recognizes standard copper clad ground rod have a life expectancy of 20 years. If the electrical system has not been upgraded, replacing the ground rod will be cheap insurance.  Its perfectly okay to have multiple ground rods connected together in an array. 
    4. National Standards recognize ground systems with less than 5 ohms of resistance as being acceptable. Unless you live in a very dry climate or have known issues, testing an installed ground rod may not be necessary. If you are thinking you need to replace it,  it’s cheaper to just add it than have it tested.OYL94SCAGD0QOUCAYL04A3CAWYLBW6CAAH81G0CA0L2SH0CAHPGADSCAA7UEPWCAR3W6D8CAEFUGXNCAWGM712CAE6Z75SCAHKAUTPCAM64A17CAYGWHLQCAY41LE9CAXSYBESCAAW9HKRCASITYXC
    5. Ensure that all CATV, Telephone, Satellite services are collectively grounded at the same location as the AC service. TIP:  The closer these services are to each other and the shorter the ground wires used to connect them; the better.  Using the proper grounding hardware, the ground wires can be connected together at the ground rod, or you can use a collection device like the one pictured.    
    6. NEVER EVER connect a ground wire or ground rod to a natural gas pipe.
    7. As noted in the Grounding Bonding Post, having all the incoming services enter the building in the same general vicinity is most desirable.  TIP: With existing houses, these services may already be installed. If you are remodeling or building, keep this item in mind as you go through the process.   When the services all enter from different locations, surges may travel through the house to reach the intended ground source. Unfortunately in those type cases, this can increase the opportunity for the surge to follow an unintended path that may include passing through a television or computer.
    8. Following these items will reduce the risk and opportunity for surges and spikes, however damage from direct strikes are nearly unavoidable. 

     Odds Stacked Against You:  Having  a good ground system as mentioned above will protect you in most cases, however there are certain issues that will work against you. Some of the conditions you can change,  some not. Either way you need to be aware of them. 

    1. Tall structure; having the tallest structure in the general vicinity
    2. Having the largest or tallest trees in the area
    3. Large antennas, such as amateur radio
    4. Located near open water
    5. Older vintage building wiring systems that did not include proper or adequate grounding
    6. Living in an area served by aerial electrical, telephone or CATV lines
    7. Living in an older neighborhood with numerous tree’s in the utility easements
    8. A combination of any of the previously mentioned situations

    I know this is a lot of information, but these grounding issues are regularly overlooked until a failure or problem has occurred. If you see the value of this, but its over your head, consult with an electrician about evaluating your system and performing the upgrades for you. My next article will cover the actual surge suppression devices (aka. TVSS). We will see the different classes of TVSS’s, where and how to apply them  and how to recognize a good one.  Look for my next post on Residential AC Surge Protection Using SPD’s and TVSS’s.