Square D whole house surge protection

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  #1  
Old 09-15-15, 08:51 PM
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Square D whole house surge protection

I'm considering two Square D options for whole house surge protection to go with my new QO panel.

First is QO2175SB, which is installed just like a 2-pole breaker directly in the panel. It's rated at 22kA.

The second is HEPD80, which goes outside the panel. It's more than 2x the cost and more difficult to install, but is rated at 80kA.

The service to the house is underground, so direct lightning strikes are less of a concern.

Anybody have experience with these devices? I have no idea how much surge protection is sufficient.
 
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  #2  
Old 09-16-15, 01:07 AM
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The HEPD80 is not really harder to install on surface mounted panels. If you have a flush mount box, they sell a bracket for flush mounting it.

The HEPD80 is a much better unit (primary surge protection) where the QO2175SB is only rated for secondary surge protection. The HEPD80 is cheap for the protection it offers.
 
  #3  
Old 09-16-15, 06:46 AM
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The service to the house is underground, so direct lightning strikes are less of a concern.

Anybody have experience with these devices? I have no idea how much surge protection is sufficient.
I had an antenna hit directly last spring. I have underground power, and all distribution is underground. I have the Sq D dual breaker/TVSS in the main load center. There were 3 ground rods in my system (now 5) with copper strapping 1.5" wide connecting them all to service.

My garage door openers suffered, with 2 out of 3 taken out with logic board damage. I had not installed Liftmaster TVSS at the garage door openers. Since, I've installed 3 surge protectors there. There was other damage to certain electronics though the house.

What happens during a "direct" strike, is that the ground reference of the house skyrockets. You get flashover arcs and any item that uses non-bonded ground references gets exposed to thousands of volts. THere was one receptacle that arced to a nearby drywall screw, blowing out the mud coat. The GDO's have metal unbonded door tracks that act as a bad reference ground. Same for the cable modem.

Anyway, just a story of what can happen with underground power. Yes, there is some reduction in threat of utility strikes, but then what is the next highest object? Home, tree, antennas. Also, there is documentation of having underground feeds directly hit.
 
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Old 09-16-15, 09:24 AM
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Wow, that's impressive. Makes me think about my own garage openers that aren't on surge protectors. Was your Sq D whole house surge protector in the load center still alive after that hit?
 
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Old 09-16-15, 10:53 AM
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Yes, the little green light is still lit.

The Liftmaster surge suppressors are not expensive, and I recommend them. The act on both the AC power and, just as important, the door sensors and controls.

Kind of ironic, that I've lived in FL for some 50 years, and never experienced any lighting damage; my last residence had a 40 foot metal tower and I had some 100 foot of overhead wire running across a salt water canal to a neighbors house. Overhead power drop.
Now, in NY, I might get 4 thunderstorms a YEAR. Underground utilities, all. And, I take a direct hit 3 years into this state... The same storm put a flaming hole in a roof a few miles away.
 
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Old 09-16-15, 11:41 AM
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@bgeery:
Looks like the QO2175SB design was upgraded so it's now TVSS as well as seconary surge protection. Here's the Square D link.

Even so, I understand your point.
 
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Old 09-16-15, 02:02 PM
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> Makes me think about my own garage openers that aren't on surge protectors.

Protection involves two factors - protector life expectancy over many surges. And protection during each surge.

Protector life expectancy means many direct lightning strikes without damage. Does not matter if utility wires are overhead or underground. Surge are still oncoming - typically 20,000 amps. So a minimal 'whole house' protector is 50,000 amps. Protectors that fail do not provide effective protection.

A direct strike to utility wires far down the street are incoming to all household appliances. It must be earthed BEFORE entering. Once inside, that current will go hunting for earth destructively via appliances. If that current is earthed outside, then ground beneath a house might even rise by 10,000 volts. That means no damage because everything inside rises by 10,000 volts. Meaning zero volts across each appliance - therefore no surge current.

Garage door openers are damaged because a surge, permitted inside, finds a path incoming on AC mains and outgoing to earth via something electrically conductive such as the door and concrete. A protector adjacent to that opener does not claim protection. In fact, it can simply give that surge more incoming paths into opener electronics. If that current is earthed upon entry, then any voltage inside increases with voltage of the concrete garage floor - so no destructive surge current.

Protectors never do protection. Effective protectors are defined by the quality of and connection to single point earth ground. That can be multiple ground rods at the service entrance. Or for venues with more serious problems, a ground wire surrounding a house (or Ufer grounds). Some facilities have protection without any protectors. In every case, protection is only defined by the one item that must always exist - single point earth ground.

Protectors are sized to survive even after multiple direct strikes. Protection during each surge is defined by the quality of and low impedance connection to single point earth ground. Any protector that does not make that low impedance connection does not claim to protect from destructive surges.

And finally, above is only your 'secondary' protection layer. Each layer of protection is only defined by that earth ground. Also inspect your 'primary' protection layer. Inspection is easier on overhead service. Pictures demonstrates what to inspect:
Florida Power & Light and BellSouth

Protection is always about where hundreds of thousands of joules harmlessly dissipate. Any protector is only as effective as its earth ground.
 
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Old 09-16-15, 03:08 PM
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Wow, really great information here. Thanks!

What I wonder is if a 80kA protector with long wires that have to run into the panel (because it's a flush mount panel) is really better than a 20kA protector mounted directly on the bus bars with the shortest possible wire to ground. The long wires increase impedance which is exactly opposite of what's needed.

As far as grounding, I'll have two 8' ground rods connected with 20' of #6 copper. I guess I'll never know if I've got enough protection until it's too late.
 
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Old 09-16-15, 03:24 PM
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A protector adjacent to that opener does not claim protection. In fact, it can simply give that surge more incoming paths into opener electronics. If that current is earthed upon entry, then any voltage inside increases with voltage of the concrete garage floor - so no destructive surge current.
I forgot to mention. In addition to the GDO surge devices, I bonded all my garage door steel tracks to the opener(s) itself. The idea being, these will surge up to the common house ground reference. Just hope no kids and dogs are near. I suspect there will be a voltage gradient locally.

Yeah, its easy for a utility to get a bit sloppy in maintenance. This is the same utility that has done a very good job in substations for bonding. You will notice that each of the 3 strand barbed wires are bonded with about #4. I've been in about 30 in the past 9 months.
 
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Old 09-16-15, 07:53 PM
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A foot of wire makes little different compared to a long hardwire (ie less than 10 feet) connecting to earth. However an 80 Kamp protector also has a side effective of a lesser voltage during a surge.

Adjacent protectors (without that earth ground) must somehow block or absorb a surge causing higher voltage. An earthed protectors with a higher current rating mean a lower voltage as it conducts even more current into earth. These are minor advantages.

Whereas most find a 50 kamp sufficient, in FL, an 80 Kamp protector may be more desirable.

BTW, its indicator light does not report all protector failures. Light only reports one type of failure that should not happen; when a protector is grossly undersized. Light indicates a last layer of protection - a thermal fuse - tripped to avert a more serious and catastrophic failure - that no protector must suffer.

How far is a connection from protector to the first rod? Hopefully less than 10 feet. Same with a hardwire connection to the telco 'installed for free' protector and to cable ground block. These hardwires are typically 10 or !2 AWG. Any antenna, invisible dog fence, automatic sprinkler system, remote gate controller, or satellite dish? These also may need to be integrated into protection.
 
  #11  
Old 09-17-15, 02:22 PM
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Let's say I'm wiring the HEPD80 to my panel. It requires a 20A breaker. Obviously 80kA is way higher than 20A. The reason the breaker doesn't trip is because the surge is such a short duration, right?
 
  #12  
Old 09-17-15, 02:53 PM
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Correct.....................
 
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