The benefits of whole house surge protection
You might have plug-in surge protectors
on some of your electronics, but you
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, exercise
machines and that new Bose Wave 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.
A full-featured whole-house surge protection
device (SPD) can protect all your
electronics, appliances, telephone,
Internet and cable TV equipment (the
Square D No. SDSB1175C is one type;
about $300 at spectrumsuperstore.com).
Electricians charge about $175 to install
it. But if you’re comfortable working
inside the main panel, you can do the job
yourself and save the installation fee. The
job takes about an hour. I’ll show you
how to do it.
Installing a whole-house surge suppression device is
the best way to continually protect your high-priced
electronics. But if you know a storm is coming, you can
protect against fried circuit boards by flipping off the
breakers to your stove, dishwasher, furnace, A/C and
fridge. Just make sure you turn them back on after the
Buying a whole house surge protector
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
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.
Even with the service
disconnect turned off, there
are still live wires inside the
main panel. If you don't know
which ones remain live, don't attempt this
project. Call a licensed electrician.
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 (see “Is a Meter Socket SPD the
First, the warnings
Even with the main breaker (service disconnect) off, there
are still live wires inside the panel. If you touch them, you
could die. So before you loosen a single screw on the main
panel cover, read how to connect a new circuit.
Read the entire article
and pay particular attention
to the diagram showing the
dangerous areas. If you have
any reservations about working
inside the main panel, call
a licensed electrician.
How to install the surge protector
1 of 4
Photo 1: 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.
2 of 4
Photo 2: 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.
3 of 4
Photo 3: 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.
4 of 4
Photo 4: Connect the telephone wires to the SPD
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.
Remove all rings and jewelry
before unscrewing the main
panel cover. Then flip the service
disconnect to “off.” Cut a
cardboard protector and place
it inside the panel to prevent
contact with live wires.
Remove the two circuit
breakers directly below the
service disconnect and relocate
them and the wires running
into them elsewhere in
the panel. Position the SPD
next to the main panel so the
wires enter it as close as possible
to the two vacant spots.
Connect the offset nipple to
the SPD and then to the main
panel (photo 1). Secure the
SPD to the wall with screws.
Next, thread the wires from
the SPD into the main panel.
Route the neutral (white) and
ground (green) wires to the
nearest screw terminals on
the neutral bus (photo 2). Make
the bends as gradual as
possible. Keep all the wires
(white, green, and black) as short
as possible. Then snap in the
new breaker and connect the
two black wires from the SPD
To install telephone and
cable surge protections, find
the service “demarcation
boxes” on the outside of your
house. Run lengths of telephone
and coaxial cable to the
new SPD and connect them
As with all electrical projects,
local electrical regulations
always trump our advice.
Always pull a permit and have
your work inspected.
Meter socket surge protector
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 about $210. It is available through our affiliation with amazon.com.