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

    February 7, 2009

    groundtermination Service Ground/Bonding Connections: Bonding and grounding are actually two subjects, but for the purpose of this article, “Bonding” serves to protect the individual from electrical shock where “Grounding” can provide a fault path for stray electrical current that might originate from a faulty electrical device or an electrical storm.  Both work hand in hand.

    Near the meter base, there should be a small wire about the size of a small straw or bigger, connected to a metal (copper/copper clad) rod. The wire could be solid, stranded with a plastic sheath or bare copper. The AC Service Panel will dictate the size of this conductor.

    Visually follow the wire to see where it goes.  This wire may go to a ground rod and/or  water pipe. Typically you should find a ground conductor attached to both as well as the electrical panel it self.  It should be firmly attached. Normally this ground wire should not have any electrical current passing through it and should be safe to touch. If the attachment is clean of corrosion and secure, no further action is required. If you find the conductor(s) cut, severed or disconnected, they must be reattached or replaced. If the conductor is completely severed, replacement is about your only choice as the NEC (National Electric Code) does not allow splicing of this conductor.  If the ground termination has signs of excessive corrosion, it should be cleaned and tightened. TIP: Clean the corrosion in the same method you would clean a automotive battery terminal. This is a very important part of the electrical system and its integrity is for your safety and your home. If you are unable to replace the conductor, hiring a professional is probably your only choice.

    Coming from the telecommunications industry, bonding and grounding was near religion. Resources were dedicated to inspect, validate and correct grounding/bonding issues regularly in large facilities. Within that plan there was typically a grounding schematic detailing proper grounding/bonding for that office. Even though every office was different, the schematic was still the same.  As we bring more sophisticated electronics into our house, a similar method is being adopted for the house. If you are a real techno-nerd and have lots of electronic gizmo’s in your house, having your house well grounded  is imperative in ensuring your equipment works well and protected from faults that may occur.  Be sure and read AC Service Ground and Bonding Connections Part II Also if you are really bored look at this Surge Protectiondocument  from the National Institute of Standards and Technology (NIST).

    With more electronics in the house, the National Electric Code (NEC) now includes the use of a bonding collection device in the current 2008 code for this purpose bringing all these ancillary grounding terminations to one location.  You will probably not have one of these devices in your house as will take the industry some time to catch up. Granted, you don’t need the device to comply with the code or complete a good grounding system but it does meet the specific need. 

    Surges and faults are typically blamed on the electrical utility but in reality the Telephone and CATV are just as large of contributor.

    You may find several ground terminations throughout your household associated with TV or Radio antennas, cable, satellite television and telephone services. Typically they will be attached to the ground system and/or the cold water pipe as this water pipe should be connected to the ground/bonding system. TIP: These devices might be connected at various locations in different ways, so don’t be surprised if you see them bonded to the AC Service Mast or piggy backed onto the ground wire with a stirrup or saddle clamp. Regardless of their location, their integrity is important to your safety and the safety of your home as well as the electrical equipment  you own.  Inspect these ground termination in the same respect as the electrical service grounding/bonding termination. In a perfect world all cables would attach to the same side of the house and the ground wires would be short and fairly straight and bringing them through the house to collect them would be avoided as any surge event will travel through the house to get to the other side and will reek havoc along the way on its search to the ground source.

    With the increased use of highly sensitive electronics found in the home, proper grounding is becoming even more important. Look for a future article on surge protection and TVSS devices.

    Key Inspection Points and Corrective Action

    1. Visually check the ground conductor(s) for physical integrity.
    2. If the conductor is completely severed, it must be replaced.
    3. Visually inspect all ancillary connections (cable, telephone, etc.).
    4. Are all ground terminations clean, secure and tight? Excessive corrosion at the terminations should be cleaned.