Dear Mr. Electrician: How do I install a surge protection device for my whole house? What is the best surge protector that will protect my computer from lightning?
Answer: Methods to install a whole house surge protector vary slightly between devices. However compared to other electrical wiring tasks installing a surge protector on your main electrical panel is relatively easy, though hazardous because of the live electrical components that you have to work around. NOTE: Text links below go to applicable products on other websites or my own posts.
Finding a surge protector that will protect your computer from lightning will involve looking at the various specifications of the many brands of surge protection devices. I think that it is best to do some homework before making a surge protector purchase. Read reviews from other purchasers, compare the product ratings, check the price ranges for your budget. Read the manufacturer’s installation instructions before purchasing. Many installation instructions are available online.
A type 1 surge protection device is rated for the line side of an electrical service before the main disconnect. This type would most likely be installed by the power company.
A type 2 surge protection device is rated for the load side of an electrical service after the main disconnect. This is what would normally get installed inside of, or attached to your main electrical panel.
A type 3 surge protection device is typically the point-of-use plug-in modules or power strips, and surge receptacles. They must be at least 30 feet or 10 meters away, as measured by the wiring distance from the main electrical service. If less than 30 feet they should also be rated for type 2.
A type 4 surge protection device shall only be installed by equipment manufacturers on, or inside of their distributed appliances and machines.
How to Install a Whole House Surge Protector
In my area a surge protector new installation is required to be inspected by the town’s electrical inspector. An electrical permit must be applied for at the building department. I submit a copy of the surge protector installation instructions with the permit application. If it is a complicated job or there are unusual circumstances I will also submit a typed, one page “Scope of Work” briefly explaining the planned installation and the materials to be used. If there is something that the inspector doesn’t like, I prefer to know about it in advance rather than after the job is done. Surge protection device installations are covered by article 242 in the 2020 National Electrical Code (NFPA 70).
When working with electricity safety is paramount and precautions should be taken. Do not wear any jewelry including watches and rings, tie back long hair, use insulated tools, and cover exposed bus bars. Read my post on safety. Shutting off the main circuit breaker will help, but I am sometimes reluctant to do that on older panels because there is a possibility that the main circuit breaker will not turn on again. Also, just because the main circuit breaker is off does not always mean that there is no electricity flowing in the panel. In some rare circumstances stray current could be on the neutral conductor. So with everything off you should still treat it as being live.
The challenge that I come across mostly is finding enough space in the circuit breaker panel and the area around it to install the surge protection device. It is particularly tricky when the circuit breaker panel is recessed inside of a wall. If it is in the garage then a hole could be cut in the wall below or above the panel depending on which end has the least amount of wires. Sometimes in those circumstances I would install a metal access panel due to the fire rating of the garage wall. Other times I would use a surge protection device that is designed for recessed mounting. Surge protection devices cannot be buried inside of a wall where they will be inaccessible.
Many brands require that their surge protection device be connected to a dedicated two pole circuit breaker. However, often I find that there are no available circuit breaker spaces available or there are no two spaces side by side for an additional two pole circuit breaker. If there are no spaces side by side, I will move some of the existing circuit breakers around until I can get room for a two pole breaker.
Existing multi-wire circuits must have their breakers side by side and should be changed to two pole circuit breakers or have approved handle ties installed while moving breakers around. See Article 210.4(B). Of course everything moved has to be relabeled on the panel cover. If the circuit breaker panel is approved for thin size circuit breakers, I will install some of them to create additional spaces.
If there are no spare spaces, then I look to see if every circuit breaker is actually in use and if I can double up some circuits onto existing breakers to free up two spaces. This must be done cautiously as I don’t want to cause a circuit breaker to be overloaded and consequently trip off as the homeowner uses power. I also do not want to cause any electrical code violations by doubling up circuits that are required to be separate such as the kitchen or laundry.
Some circuit breaker manufacturers have a combination circuit breaker and surge protector which supplies whole house surge protection while not eliminating two circuit breakers. Check with the manufacturer of your circuit breaker panel for what is approved to be installed in your panel.
EMP Shield distributes several devices that not only protect against surges, but also lightning strikes, solar flares, and electromagnetic pulses. Devices are available for your car, home, antenna, boat, RV, and solar panels. One particular item that I like is the surge protector made for circuit breaker panels recessed in a wall. Many condos and apartments, and some residential garages have the circuit breakers in a recessed panel and it is a challenge to fit a regular surge protector on the outside of them.
The EMP Shield devices are built to military standards and are competitively priced. See their surge protection devices here. Installation guides are shown on their website for each application. There is also a surge protector for European installations. NOTE: I am an affiliate for EMP Shield and Amazon.
Types of Surge Protector Installations
Some whole house surge protection devices connect to a circuit breaker while others are designed to connect directly onto the main terminals in your electrical panel without any circuit breaker protection or disconnect. Some surge protectors plug directly onto the bus bar inside of an electrical panel in the same location that a circuit breaker plugs onto. I prefer the type of surge protector installation that can be easily disconnected if necessary for replacement or servicing.
There are also plug-in surge protection modules that are used to protect one electrical appliance or component. Surge protection power strips allow several electrical items to be plugged in and protected. It is important to read the labeling on these things. Not all power strips have built-in surge protection. You should only buy something that has a UL label or other testing laboratory approval.
In addition there are surge protection electrical receptacle outlets that take the place of a regular outlet. These are nice to have because they are contained in the wall so that you don’t have an additional corded device laying on the floor.
In the 2020 National Electrical Code (NFPA 70) Article 230.67 requires an electrical service to a dwelling unit to have surge protection.
It is very important to read and follow the surge protection device manufacturer’s installation instructions. The electrical inspector will follow what the manufacturer says. Usually the wire from the surge protector to the circuit breaker must be as short as possible. Also the circuit breakers that are required tend to have a higher ampere rating than what would normally be used on that size wire.
In the photo above I put 3/8″ hex nuts under the mounting tabs of the surge protector to make it line up better with the existing 1/2″ knockout in the circuit breaker panel. Sheet metal screws were used to attach it to the plywood back board. Fender washers between the nuts and the plywood prevented the nuts from being pulled into the wood when I tightened the sheet metal screws.
Grounding Your Surge Protector
Protecting your computer, appliances, and other home electronics from lightning is not as simple as just installing a surge protector. When a surge protector limits the high voltage from a lightning strike, it will need a means to dissipate the excess current. In a well grounded home the surge protector’s lightning current would automatically be diverted to earth ground. The same is true for a plug-in surge protector power strip. The plug-in receptacle ground is connected to the grounding electrode system for the entire house and will only be as effective as the entire grounding system.
The home’s metal water service pipe, ground rods, well casing, and other metal pipes can be part of the grounding electrode system. In an older home a weak link in the system due to a loose or non-existent connection or corrosion of a component may cause the surge protector to be ineffective or in some cases hazardous.
Before purchasing a surge protector you should examine the main grounding electrode (Usually a water pipe or a ground rod or both) and the grounding electrode conductor connected to your electrical service. Lightning will usually follow the most direct path of least resistance to earth and you would prefer that it does not detour through any of your electronic equipment or appliances and cause damage.
Having an effective grounding system with surge protection will not only enhance the electrical protection of your computer equipment, but all electronic devices such as TV’s, local network components, stereo amplifiers and receivers, microwave ovens, satellite dishes, appliances, and virtually anything else that is electronically or microprocessor controlled.
Some suggested reading in the “National Electrical Code” is Article 250 Grounding & Bonding, and Article 242 Overvoltage Protection.
A good book to read about grounding is Soares Book on Grounding and Bonding
For information about protecting your home against lightning strikes you should read NFPA 780 Standard for the Installation of Lighting Protection Systems.
A good post of mine for you to read is how I grounded and bonded an older home due to the homeowners concern about lightning damage.
If you need to update your grounding electrode system you should read my post.
This Old House has a short video about surge protection.
Leviton manufactures surge protection devices that are designed to be recessed in a wall.