The Truth about Whole House Surge Suppressors

I've been reading a great deal of information/misinformation about Whole House Surge Protector (WHSP) and I wanted to make all of it more simple for the audiophile/videophile who may be on the fence about them.  

Should I get a WHSP? 

Yes.  Full stop.  No doubt about it.  The 2020 edition of the National Electric Code requires them for new construction the major justifications are the additional home automation devices (which need protection) as well as solar power panels, generators and battery backup/inverters (which cause surges)  becoming much more common.  Even before that though you probably have a lot of equipment in your home that is on 24/7 which would be expensive and time consuming to replace, such as: 

• HVAC units
• Refrigerators
• Stove
• Thermostats
• Smoke alarms
• Irrigation
• Outside lights and timers
• Wifi connected lights and outlets
  

 

A WHSP will help to protect all of them but you should still have a solid understanding of what exactly you should expect.  They are not full proof or perfect. 

Truthfully, protecting your home and electronics is a numbers game, and while homeowners who get whole house surge protection will do better than those who don't there are no guarantees that x event won't take out y device in your home.

Does a WHSP protect all of my devices?

Yes, but not equally.

All reputable WHSP makers make it clear that you should supplement their units with a good surge protector at the point of use, near the equipment to be protected.   

That's really all you need to know, but if you want to understand more, and why I make these claims, please read below.  

The Details

 

The online literature for WHSPs gets really dodgy, depending on who you are reading, either someone selling you a WHSP or a power strip, and you should get a nuanced story of what's really going on here. 

The WHSP job is to take punches for the team.  Every time there's a surge that makes it to your panel or meter the WHSP tries to take it but several factors prevent a WHSP from protecting everything at all times. Here's some of the limitations: 

• If a surge is too light ( < 600V) the WHSP may not even see it.  WHSP have higher let through voltages than a good surge strip.  Your electric range is going to be a lot less sensitive to this than your TV.
  
• If the surge is induced or starts inside the home but far from the panel the wiring itself may keep the voltage in the home several hundred volts higher than the panel ever sees.  So the WHSP may see 500V but your TV feels 1,000 V
• Almost all surge suppressors have an activation time. Lightning strikes are incredibly fast so at least some part of the leading edge is likely to get through.
  
• WHSP on your meter won't protect you from a surge coming in via the cable modem, TV antenna, etc.  
• Even if everything goes well a WHSP only softens the punch, it never 100% eliminates them.  As your equipment ages it gets closer and closer to failing with each of these light punches. 
• The quality of the wiring in your home matters, from the outlet all the way to the grounding electrode and power meter.  Even very small changes in impedance can alter how well surge protection devices can work.
  

 Another way to say this is:

The thing a WHSP does best is take on high voltage, high current surges from the power lines.  It also helps reduce the damage from internal surges caused by appliances turning off/on or induced by lightning. 

For all of these reasons most of us need a layered approach.  A WHSP in a panel or meter plus carefully selected surge protectors for our most expensive and delicate electronics.  I also strongly recommend an external coaxial surge protector if your home has any external antennas, CATV or Internet service that relies on coaxial cables.  See more below.

Installation Tips

•  Hire a registered electrician and have them inspect the ground electrode while they are there. 
• If you want to be a total geek, replace your ground electrode wire with "bare armored ground" all the way to your panel.  Because of skin effect and the high rise times of a lightning surge the BAG offers superior conductivity for lightning than bare copper.  During a lightning surge most of the current ends up in the metal sheath.  Make sure the sheath is grounded on both ends.  Yes, this is 100% code compliant. Yes your electrician will think you are a geek.
  
• If installing in your panel (and you should), install your WHSP as close as possible to the main panel breaker. 
  
• I've seen complaints about WHSP having leads that are too short.  There's a reason for this.  The longer the leads the less effective the surge suppressor can be.  Shorter is absolutely better here.
  
• Install for function, not looks.  Trim any leads as short as possible and avoid any sharp bends.  Think the radius of a soda can as the sharpest you should bend any leads or pigtail.  
• Attach as closely as you can to the incoming neutral and ground. 
• Line to neutral is more important than line to ground.  If you are installing the type with a pigtail make sure to attach it to neutral. The main reason is that the neutral cable is often much thicker than the ground in your panel, plus you avoid creating a shock hazard with a high voltage ground in your home.
• Distance matters.  If you have subpanels which are far from the main panel consider additional protection there.  This is why the 2020 NEC also requires surge protectors for attached buildings. 
• Always follow the NEC recommendations for grounding.  You may exceed them, but never create a second grounding scheme which is not bonded to the house grounding electrode.   

 

Protection from a sustained over-voltage

There is also one oddball condition that most surge strips and a WHSP won't even try to stop:  long lasting elevated voltages.  Imagine your 120V suddenly becomes 150 to 180V.  This can happen for instance with a bad neutral.  I've seen several manufacturers even put it in writing that they do not cover this condition at all.  In their mind a surge is an intense, short lasting high voltage situation.  These "over-voltages" are not surges and therefore not covered.

Some things with digital power supplies will function normally, like your PC, but any stereo equipment with a linear power supply can easily fry with long enough exposure.  Very few surge strips even see this problem happening.  For this I recommend Furman with SMP and EVS as the absolute best I know of.   

 

Coaxial Surge Protection

I strongly recommend the use of a gas discharge based coaxial surge protector to install on an external ground block.  Yes, the cable company will complain, but that's because most consumers end up using the surge protectors in cheap power strips which are often garbage for the signal.  This little gem is rock solid and because it is mounted outside your home will protect your wiring as well as internal electronics.  Use the same unit for external antennas.   I will repeat the idea though that no surge protector is perfect and that the possibility of a lightning strike inducing a damaging voltage remains no matter what you do.

 

The unit is extremely simple.  An outer grounded shell and an inner conductor.  Between them the little gas discharge tube sits and when the voltage exceeds a set amount (90V in this case) it conducts.  That's it.  The tube is reusable and replaceable. One of the most important reasons for having this unit is to prevent the coaxial cable itself from catching fire inside your home.  If you've seen pictures online of scorch marks following wiring inside the wall to a TV it's often because of a coaxial cable catching fire.  After installation I still get 500 MBPS download speeds and a strong modem signal both ways.

 

Will a WHSP protect me from internal and external power surges? 

Yes, but distance matters.  For instance, my meter is 20' from my main breaker panel. A WHSP at my meter won't shunt internal surges as well as a WHSP mounted on my panel.  The reason is the inductance in the wiring between my panel and my meter will increase the effective clamping voltage, and vice versa.  There's nothing wrong with having both.  

Can I rent WHSP? 

Depends on your power provider but a number now offer a service called Surgeguard (or something similar) where they will charge you a monthly fee for a WHSP they mount in the meter itself.  Still worth putting one into your electric panel, especially if it's not co-located with the meter.

 

What about the equipment warranty?

Read the fine print.  Most of it won't cover anything until after your insurance has, and won't cover your deductible.  

Lightning Frequency

One thing that may further motivate you to getting a WHSP is to look at the lightning frequency map.  This data is from Vaisala and used with permission.  The map covers 2015-2020.  This should give you a good idea of the risks you have from lightning strikes.  The more orange to red your county is the more likely you are to experience damaging lightning surges.

 

Surge Protector Specifications

I'm going to cover Siemens because that's what I have but most electrical panel makers have some version of what we are going to discuss. 

Breaker-less Surge Protection

Whole-house surge protectors come in a couple of flavors.  Those that require a breaker in front of them, and those which are breaker-less.  For Siemens this is the Boltshield line of products.  This is the one I use:

 

 

 

Super convenient, sounds an alarm when it's spent and you don't need extra breakers but they do take 2 slots. Now take a look at the specifications:

This particular Boltshield won't activate for any surge less than 600V.  Should excess current occur it will trip the main panel breaker, which prevents the unit itself from catching fire.  It is still worthwhile to protect all the devices in your home which don't have protection.  When the protection stops working it sounds an alarm to let you know it needs to be replaced. 

 

Square D also offers these types of surge protectors, such as the HomeLine which claims they clamps way down at 175V.

 

Bad news is that it doesn't have an alarm to tell you it's spent.  You have to keep checking that light.