Greetings,

I'd like to run electrical and telephone service to my storage shed, which is located 40'
from my home. I'd appreciate any advice that the experts in this group can provide.

I am planning on a 20' 4x4" pole at the shed, buried 5', with a pair of Par-38's near the
top of the pole for general yard lighting. There will be a single 15A outlet inside the
shed, which will supply handheld power tools and low-voltage lighting around the shed.

The entire electrical circuit will be three-way switched, similar to a stairwell, with one
switch inside the house and the other inside the storage shed. See
http://www.lightingfacts.com/psls.JPG . I'll use a single-gang digital timer inside the
house, if such a beast exists for three-way circuits @ a full 15a (doubtful).

The voice cable will terminate inside the shed.

I cannot bury the cabling because the roots of a very large, very healthy oak tree lay in
the most obvious path of a trench. I do not want to risk killing the tree, so trenching
is out of the question.

However, the lower limbs of the tree are at least 15' above ground, in the direct path
between my service entrance, and the storage shed. If the overhead cable was carefully
strung, it could easily maintain 2-3' of clearance under the lowest branches. Judging
from some of the other electrical work around my neighborhood, it appears that you are
allowed to have wire suspended underneath a limb.

Questions thus far:

1 What type of electrical cable, and voice cable, are required for overhead suspension,
given the application (note the 3-way switch requirement)? Is the cable self-suspending,
or is some type of separate weight-bearing carrier required?

2 Can the electrical and voice cables be run in close proximity?

3 Is a service disconnect required on the house end of the run, or can I simply use a new
breaker in my 200a panel?

4 Should I use a 15a GFCI inside the shed, or a circuit-breaker type GFCI in the 200a
panel?

5 What gauge electrical wire is appropriate? I estimate the entire run, from the breaker
to the farthest point, at 115'.

6 How high for the suspension points? How high for the lowest point on the overhead run?

7 For safety and durability, I want to conduit the runs at both ends, from the suspension
point to the entrance point. What kind of junction is appropriate between the pipe and
the overhead cable? Between the pipe and the interior cable? Can Romex be run through
conduit, or must THHN be used?

Best regards,

Tim ==
(substitute 'tcsys.com' for 'nospam.co.uk')
_________________

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Questions thus far:

1 What type of electrical cable, and voice cable, are required for overhead suspension,
given the application (note the 3-way switch requirement)? Is the cable self-suspending,
or is some type of separate weight-bearing carrier required?

Quadplex cable is three insulated aluminum conductors wrapped around an
aluminum clad steel reinforced conductor that will serve as the
Equipment Grounding Conductor (EGC) as well as being the messenger that
supports the other three conductors.

2 Can the electrical and voice cables be run in close proximity?

NO! It is dangerous to do so and it will induce noise into the voice
circuit.

3 Is a service disconnect required on the house end of the run, or can I simply use a new
breaker in my 200a panel?

You will need to provide a service disconnect at the garage end of the
circuit but if you have a pair of three way switches that will open all
of the ungrounded conductors that is all that is required on residential
property. No separate disconnect is required at the house end.

4 Should I use a 15a GFCI inside the shed, or a circuit-breaker type GFCI in the 200a
panel?

I would use the GFCI as the first receptacle in the shed in order to
avoid nuisance tripping due to leakage current in the overhead span
during wet whether.

5 What gauge electrical wire is appropriate? I estimate the entire run, from the breaker
to the farthest point, at 115'.

If the entire run were going to be the aluminum triplex then you would
need six gauge to avoid excessive voltage drop. I would imagine that
eight gauge would be fine since it is less than half of the total run
length. I assumed a twenty ampere total load for that calculation.

6 How high for the suspension points? How high for the lowest point on the overhead run?

225.18 Clearance from Ground.
Overhead spans of open conductors and open multiconductor cables of not
over 600 volts, nominal, shall conform to the following:
(1) 3.0 m (10 ft) — above finished grade, sidewalks, or from any
platform or projection from which they might be reached where the
voltage does not exceed 150 volts to ground and accessible to
pedestrians only
(2) 3.7 m (12 ft) — over residential property and driveways, and those
commercial areas not subject to truck traffic where the voltage does not
exceed 300 volts to ground
(3) 4.5 m (15 ft) — for those areas listed in the 3.7-m (12-ft)
classification where the voltage exceeds 300 volts to ground
(4) 5.5 m (18 ft) — over public streets, alleys, roads, parking areas
subject to truck traffic, driveways on other than residential property,
and other land traversed by vehicles, such as cultivated, grazing,
forest, and orchard

7 For safety and durability, I want to conduit the runs at both ends, from the suspension
point to the entrance point. What kind of junction is appropriate between the pipe and
the overhead cable? Between the pipe and the interior cable? Can Romex be run through
conduit, or must THHN be used?

Install service heads on the tops of both raceways. Splice the quadplex
to the conduit wiring using pre insulated patent splices that are
available from any decent electrical supply house. Each conduit will
terminate in an LB that connects to a Jbox located inside the building.
Make your transition from the raceway wiring to cable in the junction
box. It is currently a matter of debate whether it is permissible to
run NM cable in conduit. I think it is a poor practice at best and
would recommend avoiding it.

Best regards,

Tim ==

Other questions please ask.
--
Tom H

Questions thus far:

1 What type of electrical cable, and voice cable, are required for overhead suspension,
given the application (note the 3-way switch requirement)? Is the cable self-suspending,
or is some type of separate weight-bearing carrier required?

Quadplex cable is three insulated aluminum conductors wrapped around an
aluminum clad steel reinforced conductor that will serve as the
Equipment Grounding Conductor (EGC) as well as being the messenger that
supports the other three conductors.

2 Can the electrical and voice cables be run in close proximity?

NO! It is dangerous to do so and it will induce noise into the voice
circuit.

3 Is a service disconnect required on the house end of the run, or can I simply use a new
breaker in my 200a panel?

You will need to provide a service disconnect at the garage end of the
circuit but if you have a pair of three way switches that will open all
of the ungrounded conductors that is all that is required on residential
property. No separate disconnect is required at the house end.

4 Should I use a 15a GFCI inside the shed, or a circuit-breaker type GFCI in the 200a
panel?

I would use the GFCI as the first receptacle in the shed in order to
avoid nuisance tripping due to leakage current in the overhead span
during wet whether.

5 What gauge electrical wire is appropriate? I estimate the entire run, from the breaker
to the farthest point, at 115'.

If the entire run were going to be the aluminum triplex then you would
need six gauge to avoid excessive voltage drop. I would imagine that
eight gauge would be fine since it is less than half of the total run
length. I assumed a twenty ampere total load for that calculation.

6 How high for the suspension points? How high for the lowest point on the overhead run?

225.18 Clearance from Ground.
Overhead spans of open conductors and open multiconductor cables of not
over 600 volts, nominal, shall conform to the following:
(1) 3.0 m (10 ft) — above finished grade, sidewalks, or from any
platform or projection from which they might be reached where the
voltage does not exceed 150 volts to ground and accessible to
pedestrians only
(2) 3.7 m (12 ft) — over residential property and driveways, and those
commercial areas not subject to truck traffic where the voltage does not
exceed 300 volts to ground
(3) 4.5 m (15 ft) — for those areas listed in the 3.7-m (12-ft)
classification where the voltage exceeds 300 volts to ground
(4) 5.5 m (18 ft) — over public streets, alleys, roads, parking areas
subject to truck traffic, driveways on other than residential property,
and other land traversed by vehicles, such as cultivated, grazing,
forest, and orchard

7 For safety and durability, I want to conduit the runs at both ends, from the suspension
point to the entrance point. What kind of junction is appropriate between the pipe and
the overhead cable? Between the pipe and the interior cable? Can Romex be run through
conduit, or must THHN be used?

Install service heads on the tops of both raceways. Splice the quadplex
to the conduit wiring using pre insulated patent splices that are
available from any decent electrical supply house. Each conduit will
terminate in an LB that connects to a Jbox located inside the building.
Make your transition from the raceway wiring to cable in the junction
box. It is currently a matter of debate whether it is permissible to
run NM cable in conduit. I think it is a poor practice at best and
would recommend avoiding it.

Best regards,

Tim ==

Other questions please ask.
--
Tom H

On Mon, 01 Dec 2003 17:46:36 -0600, Timothy J. Trace
wrote:

I'd like to run electrical and telephone service to my storage shed, which is located 40'
from my home. I'd appreciate any advice that the experts in this group can provide.

Okay, but it's the advice of the experts at your local building
official's office that really matter to you...

I am planning on a 20' 4x4" pole at the shed, buried 5', with a pair of Par-38's near the
top of the pole for general yard lighting. There will be a single 15A outlet inside the
shed, which will supply handheld power tools and low-voltage lighting around the shed.

The entire electrical circuit will be three-way switched, similar to a stairwell, with one
switch inside the house and the other inside the storage shed. See
http://www.lightingfacts.com/psls.JPG . I'll use a single-gang digital timer inside the
house, if such a beast exists for three-way circuits @ a full 15a (doubtful).

The voice cable will terminate inside the shed.

I cannot bury the cabling because the roots of a very large, very healthy oak tree lay in
the most obvious path of a trench. I do not want to risk killing the tree, so trenching
is out of the question.

Directed boring might be a better option, or a route around the tree.
Burial is always preferable, and locally it's required.

However, the lower limbs of the tree are at least 15' above ground, in the direct path
between my service entrance, and the storage shed. If the overhead cable was carefully
strung, it could easily maintain 2-3' of clearance under the lowest branches. Judging
from some of the other electrical work around my neighborhood, it appears that you are
allowed to have wire suspended underneath a limb.

Questions thus far:

1 What type of electrical cable, and voice cable, are required for overhead suspension,
given the application (note the 3-way switch requirement)? Is the cable self-suspending,
or is some type of separate weight-bearing carrier required?

Quadplex cable is self-suspending, and though I don't like the stuff
it would likely be suited to your installation. It's aluminum so you
need appropriate terminations. Locally it's common for mobile homes
and small sheds such as yours, though as of last year locally we're
required to bury cable and not run overhead. For the voice, you'll
want a suspending wire run with it to strap the cable to, though I'd
recommend burial, either direct or in conduit. Direct burial would
miss tree roots for the most part.

2 Can the electrical and voice cables be run in close proximity?

No. Generally a three foot separation, though you can run low voltage
voice lower than the height requirement for electrical feeds. But you
can also bury the voice cable quite easily and that may be the best
option.

3 Is a service disconnect required on the house end of the run, or can I simply use a new
breaker in my 200a panel?

Check your local jurisdiction on this. You should be able to use a
disconnect on the shed end, with none on the house, but local
interpretations sometimes interfere.

4 Should I use a 15a GFCI inside the shed, or a circuit-breaker type GFCI in the 200a
panel?

I like the breaker, but I'm tempted to say a GFCI in the shed end as
the first device on the line. Aerial runs can induce some false
tripping in GFCI.

5 What gauge electrical wire is appropriate? I estimate the entire run, from the breaker
to the farthest point, at 115'.

At 20 amp, that works out to a 8 guage, but I'd upsize to 6 on the
aerial run, especially in aluminum.

6 How high for the suspension points? How high for the lowest point on the overhead run?

No closer than 10' from ground, though some jurisdictions may have
other rules. Check with yours to be sure. 12' if you're over a
driveway, even a dirt vehicle path. A pool would alter this even
more.

7 For safety and durability, I want to conduit the runs at both ends, from the suspension
point to the entrance point. What kind of junction is appropriate between the pipe and
the overhead cable? Between the pipe and the interior cable? Can Romex be run through
conduit, or must THHN be used?

THHN in conduit, spliced to the quad cable at a service head atop the
conduit/mast on both ends. Romex can't be in conduit, so in your
situation I'd run conduit to the first receptacle with THHN, then use
Romex if appropriate for the rest. Make sure to use the correct
splices to go from aluminum to copper, and rent or borrow the
appropriate crimpers.

Although actually, I'd run a subpanel in the shed and at least 30 amp
(likely 40 to 60) from the main. You'll surely want to add lights,
outlets, etc. at a later date anyway.

Jeff