Install Whole House Surge Protection

What is a whole house surge protector, and how hard are they to install? Find out here.

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The benefits of whole house surge protection

Most people have plug-in surge protectors on some of their electronics, but probably don’t have them for appliances with electronic circuit boards. Those electronics are sitting ducks for power surges generated by lightning strikes (even if the strike is miles from your home). Most newer appliances, cable boxes, exercises machines and that new 60-inch 4K TV are all at risk. And it’s not just lightning. Damaging power surges on the grid are common even when there isn’t lightning around. It doesn’t take much of a power surge to wipe out delicate electronics. It often costs as much to replace a circuit board as it does to buy a new device.

That’s why everyone should have a whole-house surge protector. Those who live in rural areas are particularly vulnerable, especially if you live near the end of the power line. There’s nowhere else for the surge to go but into your house.

Buy the right SPD

There’s a lot of manufacturer hype surrounding surge protectors. Ignore all the mumbo jumbo and head right for the specifications. SPDs are rated in kiloamps (1kA equals 1,000 amps). The really inexpensive SPDs start at about 10kA. They can handle one really large surge and then they’re toast—so they’re a bad long-term investment.

Instead, look for an SPD with a minimum rating of 50kA. It’ll last longer than a 10kA device.

If you’ve got telephone, DSL, cable or satellite service, get an SPD that protects those lines as well. Finally, make sure the device you choose complies with the most recent UL No. 1449 rating. Not all the equipment on the market meets the newer standard. Once you decide on an SPD, you’ll also need a double-pole 15-amp breaker, one 1/2-in. rigid offset nipple and two 1/2-in. locknuts.

Can you install it yourself?

You’ll need two blank spaces, one on top of the other, in your main panel to hook up the SPD. Or, you can connect it to an existing two-pole 240V breaker—but only if that breaker is rated for two wires. To find out, call the breaker manufacturer’s tech support line. If you don’t have two blank spots in your main panel or the existing breakers aren’t rated for two wires, you’ll have to hire an electrician to install a subpanel. Or consider buying an SPD that installs right in the meter box.


Even with the main breaker (service disconnect) off, there are still live wires inside the panel. If you touch them, you could die. If you have any reservations whatsoever about working inside the main panel, call a licensed electrician.

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Step One: Secure the offset nipple to the main panel

Remove a knockout on the main panel and insert the offset nipple. Spin on the dimpled locknut with the locking “ears” facing the wall of the panel. Then tighten it with a flat-blade screwdriver and hammer.

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Step Two: Connect the neutral and ground to the bus

Strip off 3/4 in. of insulation from the neutral (white) and ground (green) wires and secure them to separate screws on the neutral bus.

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Step Three: Cut the black wires to length and install

Mark the two black wires from the SPD (a silver permanent marker works well). Then cut them to length and strip the insulation. Insert the bare wire into the breaker screws and tighten.

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Step Four: Connect the telephone wires to the SPD

To install telephone and cable surge protections, find the service “demarcation boxes” on the outside of your house. Run the telephone wires from the demarcation device to the “in” connectors on the telephone SPD. Connect the house phone lines to the “out” terminals. Follow the same procedure for the cable TV lines.

Surge Protector | Construction Pro Tips
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Is a Meter Socket SPD the Answer?

If your electrical panel is full or you’re not up to doing your own installation, a meter socket SPD may be the perfect alternative. It snaps into the meter socket. Start by checking with your local power utility to see if it will allow a meter socket SPD. If so, find out how much it charges for installation—you can’t install it yourself. Shown is the Leviton No. 50240-MSA, which is $210 at