We’ve been over this before. You’re not even willing to look at the interior of a building, only the exterior and we all live inside a building, not on the outside. If makes you feel easier, remove any bias by a surge protection manufacturing company and just consider that both the IEEE and NIST have recommended a cascade (layering) approach to surge protection for a home, with a unit at the service entrance and point of use devices throughout the home. The one at the service entrance deals with external surges and the ones throughout the home deal with any surges coming in from the outside (that made their way past the service entrance SPD and any internal surges).



IEEE (The Institute of Electrical and Electronic Engineers) states that 6000V is the largest transient that the interior of a building would experience. IEEE defines its harshest interior surge environment as one that could experience 100 surges of 6000V, 3000A (category B3 waveform). A federal guideline recommends that a surge protector utilized in a harsh environment should be capable of withstanding 1000 surges of 6000V, 3000A or ten (10) years worth of IEEE’s category B3. Note any surge that is harsher would cause #14 gauge houses wiring to vaporize, not just melt and at this point you have bigger fish to fry. The point is if you use Type 3 SPD’s that can withstand the harshest surges that can exist in the interior of a building you’ve got something.



The government chose UL (Underwrites Laboratories) to provide the adjunct testing service (in addition to the 1449 safety classification) that will test to the 1000 surge, 600V, 3000A federal protocol. Many manufacturers (all who cared to participate), IEEE, UL, federal engineers, NIST and others worked for a year and a half in developing the Adjunct Classification. Passing such a test is a virtual guarantee that a surge protection device will never experience a surge related failure. The tests will be clearly marked as to Class, Grade and Mode. A Class 1, Grade A, Mode 1 (L-N) is optimal, providing the most suppression for the longest time. Early in 1996 UL applied 1000 surges (at 60 second intervals) of 6000V, 3000A to an off-the-shelf Series Mode Surge Filter. There was no failure. There was no performance degradation. Let through voltage did not exceed 290V (certified by UL). You cannot do any better than this for a building interior surge suppressor.



We should all demand UL endurance test results. Sadly no MOV based SPD manufacturer will submit their device to this test as the results would in all likelihood not be pleasant and would not translate into something that could be used by marketing.



A Whole House surge protector will not protect against a direct lightning strike - nothing will. Yet it’s not without merit it and can help to protect a home from destructive external surges and thank-you for agreeing that it’s not 100% protection. That took a lot of courage on your part.



This is where a Series Mode filter shines. It solves potential issues in a home where a high impedance return path may exist. No one knows the state of the internal wiring but it’s a good bet that it’s not point to point and has sharp 90 degree turns. Type 3 in-house point of use MOV’s could be undersized besides having impedance path return issues. Series mode devices work precisely because they slow the surge down in real time and take the impedance return path issue out of the equation. That they eliminate and not just divert the surge is like having your cake and eating it too. Note again, that no one is talking about place a series-mode power filter in a Type 2 location as the first line of protection. A series-mode power filter also solves the issue with building that only has 2-prong (no safety ground) outlets because it does not rely on the Safety Ground to divert the surge. In fact series-mode solves many noise related issues because it filters out unwanted noise.



As for their (series-mode) sales brochure regarding surges (both internal and external) much of this originates in IEEE and NIST white papers. That a manufacture picks up and promotes the issues and how they believe their product solves the issue nothing new.



I believe that if you have to start somewhere, start with point of use Type 3 SPD’s and if you don’t want to invest in new series mode power filters, consider used or new old stock available on popular auction sites for as little as $30, but often in the $60-$75 range. New 2-outlet 7.5Amp/15Amp models from Zero Surge would be the least expensive new options in the $140-$160 range. You don’t have to throw away your old MOV based Type 3 SPD’s since you can plug them and any UPS into a series mode to provide protection to the UPS or more useful outlet combinations.



Then secure the coaxial & phone connections (if still used) at their respective service entrances to the building, and finally



Invest in a decent Type 2 Whole House SPD to protect from external destructive surges. This is a layered approach.



I think you and I are in agreement on Type 3 MOV based SPD’s not being able to provide protection on account of the impedance issue and possibly on the sizing of the MOV. This is where the Series Mode Type 3 SPD solves this issue.



I think you and I are also in agreement on the use of Type 2 MOV based SPD at the service entrance being a solid 1st line of defense. It’s just the order of implementation where we disagree. The approach I take considers the type of surge that can exist on house wiring and solving that problem first, then securing the coax/phone entrances and lastly adding a Type 2 SPD at the service entrance for electrical protection.



As for the other articles & links you’ve provided, they are nice to read but not really geared for a homeowner, rather mainly to those interested in learning more. The DSL discussion points out all the problems with using point of use Type 3 MOV based SPD’s sharing a common ground (i.e. contributing to ground contamination). We shouldn’t have to become experts in this field but the SPD industry is a multi-billion dollar industry and growing 5.6% each year and as we’ve seen uses all sorts of marketing tactics (some even claimed as recently as 6 months ago that they had a let-through voltage rating of 40 Volts for their popular 3020J SurgeArrestor). In the end it all comes down to risk and how to minimize that risk (i.e. what makes you sleep at night).