to install conduit
on your PV system's electrical wiring.
Installing conduit is one task you can't get around when
you solar power your house yourself.
If a solar installer ever tries to
install a pv system on your house without using conduit to protect the wiring, you may want to call
the power company and ask them if conduit installation is necessary with pv
If they say yes (which they will),
fire him immediately before he burns down your house.
Before you learn how to install conduit, let's first learn exactly
what conduit is.
Conduit is a hard, durable protective tubing that completely
covers and protects wires or cables used in electrical applications that typically need
protection from exposure to sunlight and other elements.
When installing conduit, wire is pulled through the conduit tubing
and then typically passed through walls, under driveways, secured to the exterior and even to the
interior of a house. Basically conduit installation protects the wires running
through your walls, underground, on your roof, or down the side of your house.
In a solar power system without conduit, your outdoor wires could get wet,
eventually corrode and your pv system would likely suffer extensive and expensive damage. Also
without conduit the wires in your walls could heat up and start a fire. Installing conduit
is necessary to protect your wires from all exterior or interior elements and
Types of Conduit
Some of the more popular types of conduit that are
used in electrical work include: rigid-steel, electrical metallic tubing (EMT), rigid non-metallic
(poly vinyl chloride - PVC), and flexible metallic and nonmetallic conduit.
Rigid-steel conduit is the
strongest type of conduit casing and sort of resembles a thick metal pipe
that is threaded on both ends. Due to it's superior strength and durability rigid-steel
conduit is considered to be one of the best choices for protecting wires when installing
However this also makes it the hardest
conduit to bend or cut and sometimes requires a professional to do it
right. To cut it yourself,
you'll need a hacksaw or a pipe cutter and possibly a clamp or vise to keep it from moving. Cut at
a 90° angle.
After cutting (and before conduit installation),
you'll need to file the sharps edges down and thread the conduit so you can use threaded couplings,
locknuts and bushings.
To bend rigid-steel conduit, you can use a manual
bender or have it factory bent, however factory bending is much more expensive.
Rigid-steel conduit is available in sizes from 1/2 inch to 6 inches in diameter and up to 10
feet in length. You can learn more about installing steel conduit by clicking
here to access The Guidelines For Installing Steel Conduit Tubing pdf guide.
For installing conduit in damp areas or underground, galvanized steel conduit is used to prevent
moisture and rusting. You can learn more about underground conduit applications by
clicking here to learn how to connect conduit in an underground garage setting.
Electrical Metallic Tubing (EMT)
Electric metallic tubing conduit (also known as
thin-wall conduit) is similar to the rigid-steel type, but the walls are 40% thinner, which
makes it easier to bend but relatively less durable.
In other words, electric metallic tubing conduit is
easier to shape but not as tough.
To cut electric metallic tubing conduit, you'll need a hacksaw or tubing cutter and
possibly a clamp or vise to keep it from moving. Cut at a 90° angle. After cutting you'll need to file the sharps edges down before installing
An EMT bender can be used to bend EMT conduit.
Electric metallic tubing (EMT) conduit is available in sizes from 1/2 inch to 4 inches in
diameter and up to 10 feet in length.
Rigid Nonmetallic (PVC) Conduit
Rigid Nonmetallic Conduit (also known as PVC conduit) is made of a rugged plastic and thus is ideal for underground conduit
installations including direct burial and concrete encasement installation. Installing conduit
that is made out of plastic is cheaper, plus it's strong, waterproof and has a low absorption
To cut it, you'll need a hacksaw or tubing cutter and possibly a clamp or
vise to keep it from moving. Cut at a 90° angle. After cutting,
you'll need to file the sharps edges down.
PVC conduit is available in sizes from 1/2 inch to 5 inches in diameter and
up to 20 feet in length.
Flexible Metallic Conduit
Flexible metallic conduit is made of either steel or
aluminum and typically used for conduit installation in areas where there may be movement or
vibration. You can also get it for use in wet conditions.
To cut it, you'll need a hacksaw and possibly a clamp or vise to keep it
from moving. Cut at a 90° angle.
Flexible metallic conduit is available in sizes from 3/8 inches to 4 inches
in diameter and you can basically get any length you want.
To learn more about the types of conduit available for use in
residential and commercial home and business electrical and solar photovoltatic applications,
click here to check out this article on conduit tubing.
Installing conduit consists of measuring out the length of the conduit, cutting,
threading and bending it to fit the requirements of your project, installing the fittings and
supports, securing the conduit into place and installing the couplings/connectors, connecting to
the outlet boxes, pulling the conductor (wire) through the conduit tubing and making / securing /
testing the connections.
When installing conduit make your runs of conduit as straight and
direct as possible and avoid any unnecessary bends.
How To Install Conduit
Fittings, Connectors and Couplings
Fittings for EMT conduit come in both ¾
water-tight for installing conduit in wet areas and non-water tight for dry areas.
Concrete-tight and water-tight connectors and couplings are also required for
concrete and wet applications respectively.
Fittings for rigid-steel and PVC conduit are similar to EMT fittings. You can
get threaded or threadless couplings and connectors for rigid-steel and PVC conduit.
With threadless, there is no threading of the conduit
required. EMT conduit is too thin and cannot be threaded, therefore uses only threadless couplings and connectors.
On rigid steel conduit
installation, threaded couplings are screwed onto the threaded
ends of the conduit and a pipe wrench is used to tighten
them. Rigid-steel and PVC conduit is connected to
electrical boxes using locknuts and bushings.
Fittings for flexible metallic conduit are attached to the
conduit either by screwing them on (internally) or with clamping screws
(externally). For installing
conduit in wet areas, liquid-tight fittings are used.
The next part of the process involves connecting the conduit pieces
together. PVC conduit connections are welded together using a solvent cement resulting in a strong,
water tight bond. Just coat them in primer and apply some cement to each piece of PVC to stick them
together. Since PVC is plastic, it can be cut easily with a
regular fine tooth saw.
In conduit installation, all pieces of conduit are connected with what is
called a "conduit body".
A conduit body is a special kind of
fitting that functions a lot like a junction box and is used in
between connecting conduit pieces to keep the number of
bends to a minimum. This is because most electrical codes require you to keep your total
bends for one piece of conduit to 360° and under.
So if when installing conduit, you had 4
bends of 90°, you would need to install a conduit body. And with 8 bends of 45°, you'd need to
install a conduit body. You get the idea.
Straps or hangers are used to support all conduit throughout the entire
Only after you have finished installing conduit and securing it to the electrical boxes, can you pull
the conductor (wire) through and make your final connections to the photovoltaic
Now that you know more
about how to install conduit, click here to go back to the Solar Power Installation section in
the exact spot you left off (or just click your browser's back