I'm building a new shop ( no metallic connections ) about 150' from my
house. The shop will have a new 200amp service panel and I'll be
feeding it from a 200amp disconnect panel at the house. My question
is: How difficult is it going to be to pull the required 4/0 - 3
conductor aluminum wire through about 165' feet of 2.5" conduit? I've
never done this before. Any tricks to making it easier?
I pulled in two 4/0 (hots) 2/0 (neutral) and a #4 (ground) XHW aluminum 115'
from my yard panel to my house. It was in 2 1/2 PVC conduit with three 90°
bends in the run. I bought triplex with the reduced size neutral and added
the ground wire. You might want to use the reduced neutral because it will
be easier to pull. As a separate building on the same premises you can skip
the ground wire and just use a bonded neutral, but I would recommend
separate ground wire. If you do run a separate ground, the panel will have
a unbonded neutral bar that all of the white wires will go to and the ground
wires will go to a ground bar you screw to the panel metal.
I used a come-along inside to pull with the come-along tied off to a ceiling
joist. Make sure that you use a strong pull rope. Stagger the ends of the
various wires and cut them off at a shallow angle so that the bundle gets
progressively larger instead of forming flat front bumps. Either use a big
enough pulling grip, or you can use lots of tape and make sure to wrap the
rope around the wire several times with a timber hitch so the wires can't
slide out of the rope. I used the knot with several timber hitches to pull
mine. The whole taped off area will need to be several feet long to prevent
one of the wires from slipping out.
When you go to pull, make sure to use lots of pulling lubricant. Lube the
wires will to prevent chafing and make them slide easier. I can't over
emphasize how important pushing is when you get to this size wire,
particularly if you go with aluminum. It's very important to have two people
working together so one can pull while the other pushes. Put the stronger
person in the push position because the puller has the com-along to multiply
force. The push person will literally climb the wires and use body weight
to push them down.
Although not strictly legal I see the power company pulling in the
straight stretch before they glue on the sweeps for the risers.
A legal way to do it is to put an LB or LL or LR at the turn ups, pull
in the wire and cap the conduit body.
I saw the contractor on "This Old House" use compressed air to blow a plug,
with a rope attached, through a conduit (for a 200 amp outbuilding service),
and then use the rope and his pickup to pull the wires for a 200 amp
underground service, as a unit, through the installed conduit - as his
partner aligned and fed the cables into the end.
Not my first choice, but if the ends of the conduit aren't sharp, and the
wires are well gripped, etc., and they don't pull the wires so hard they
stretch, and the rope strength was sized so it broke before the several
cables stretched... I suppose...
I remember the assistant was on the pole feeding the cable in, but I don't
remember exactly how they routed it out of the conduit at the truck end - I
think he ran the rope over a hook/pulley above the open end of the conduit
(you don't need to bend the wires after they come out - just stop pulling
then they are a foot or so straight up out of the end of the conduit.)
( I imagine if you are not careful and you did stretch the cable and it
broke, you would be pulling cable back out of the conduit, or laying more
conduit -and that would be more irritating to the contractor than just about
anything else -- so on that basis alone I figured it must be a tried and
true method in the northeast.)
(FWIW - you can pull the wire through from either end)
3-4/0 ? No equipment grounding conductor? Be sure and review the 2005
NEC Section 250.32 quoted below.
For 2 - 90 degree bends at 13 inch radii and using a pulling lubricant
I come up with 100 to 153 pounds pulling tension. This assumes that
some one is feeding the other end so the pulling tension into the first
bend is zero. If you are pulling off a reel by yourself this could
compound the required pulling tension since the bends have a
mulitplying effect on the icoming pulling tension. I used my calculator
based on a study by the ICEA at:
250.32 Buildings or Structures Supplied by Feeder(s) or
(A) Grounding Electrode. Building(s) or structure(s) supplied
by feeder(s) or branch circuit(s) shall have a grounding
electrode or grounding electrode system installed in
accordance with 250.50. The grounding electrode conductor(
s) shall be connected in accordance with 250.32(B) or
(C). Where there is no existing grounding electrode, the
grounding electrode(s) required in 250.50 shall be installed.
Exception: A grounding electrode shall not be required
where only a single branch circuit supplies the building or
structure and the branch circuit includes an equipment
grounding conductor for grounding the conductive non-
current-carrying parts of equipment. For the purpose of
this section, a multiwire branch circuit shall be considered
as a single branch circuit.
(B) Grounded Systems. For a grounded system at the
separate building or structure, the connection to the grounding
electrode and grounding or bonding of equipment,
structures, or frames required to be grounded or bonded
shall comply with either 250.32(B)(1) or (B)(2).
(1) Equipment Grounding Conductor. An equipment
grounding conductor as described in 250.118 shall be run with
the supply conductors and connected to the building or structure
disconnecting means and to the grounding electrode(s).
The equipment grounding conductor shall be used for grounding
or bonding of equipment, structures, or frames required to
be grounded or bonded. The equipment grounding conductor
shall be sized in accordance with 250.122. Any installed
grounded conductor shall not be connected to the equipment
grounding conductor or to the grounding electrode(s).
(2) Grounded Conductor. Where (1) an equipment
grounding conductor is not run with the supply to the building
or structure, (2) there are no continuous metallic paths
bonded to the grounding system in each building or structure
involved, and (3) ground-fault protection of equipment
has not been installed on the supply side of the feeder(s),
the grounded conductor run with the supply to the building
or structure shall be connected to the building or structure
disconnecting means and to the grounding electrode(s) and
shall be used for grounding or bonding of equipment, structures,
or frames required to be grounded or bonded. The
size of the grounded conductor shall not be smaller than the
larger of either of the following:
(1) That required by 220.61
(2) That required by 250.122
I wouldn't mess with anything but the UL listed lubricant. You have to
worry about the condition of the wire insulation for the next 50 years. The
listed lubricant has been tested specifically for insulation degradation.
Anything else hasn't.
Can you bury an LB (in dirt)?
I have heard that the friction from the pulling rope can cut into a PVC
elbow but I don't have experience with runs like this. NEC 250.80
permits isolated metal elbows in service runs (but presumably not
feedeers) to avoid this problem if there is a minimum cover of 18". You
could use a metal elbow with metal conduit to the panel.
An electrician would probably use a pulling grip. Without that I would
strip the wire ends and bend one back through a loop in the end of the
pulling rope. I would reduce the number of strands on the rest of the
wires and bend the ends of them back through the loop in the pulling
wire staggering the full size ends away from the end of the rope. Use
tape to keep the wires bent through the pulling loop and use plenty of
tape to keep the bundle smooth. As Michael said, use plenty of wire lube
and push the wires in. Be careful to avoid crossovers. The loop in the
pulling rope is the weak point.
Particularly if using mechanical advantage consider the forces on the
panel and conduit.
There are some electricians at alt.home.repair if you want advice beyond
I have bad news for you. Your shop will either have to be supplied
through a rather expensive special order 180 ampere breaker or you're
going to have to run 250 MCM cable. A shop is not a dwelling unit. You
cannot use the amperage table for dwelling unit services from Table
310.15(B)(6) to select your conductor size. You must use the size
called out by table 310.16.
Tom, I disagree.
The 200 ampere breaker protects both the 90 degree 4/0 aluminum rated
at 205 amperes terminated on a 75 degree terminal rated at 180 amperes
and a 75 degree C. insulated conductor rated at 180 amperes since we
can size up per sect 240.4.
240.4 Protection of Conductors. Conductors, other than
flexible cords, flexible cables, and fixture wires, shall be
protected against overcurrent in accordance with their ampacities
specified in 310.15, unless otherwise permitted or
required in 240.4(A) through (G).
(B) Devices Rated 800 Amperes or Less. The next higher
standard overcurrent device rating (above the ampacity of
the conductors being protected) shall be permitted to be
used, provided all of the following conditions are met:
(1) The conductors being protected are not part of a multioutlet
branch circuit supplying receptacles for cordand-
plug-connected portable loads.
(2) The ampacity of the conductors does not correspond
with the standard ampere rating of a fuse or a circuit
breaker without overload trip adjustments above its rating
(but that shall be permitted to have other trip or
(3) The next higher standard rating selected does not exceed
You probably won't believe this, but when we built the trans-alaska
pipeline pump stations and north slope facilites we had to pull in sub
zero temperatures. UL listed pulling lubricant froze solid, so we made
our own using glycol anti freeze, soap and water. I guess it didn't
hurt anything because most of those runs are still in service some 30
All right you got me. I had, incorrectly obviously, believed that 180
amperes was a standard size under the code. So since the conductor
ampacity is 180, and thus five amperes over the next lowest standard
fuse or breaker size, you can protect it with a two hundred ampere
breaker. That assumes that the computed load is actually only 180
amperes or less which seems likely. It would be a good idea to label
the building disconnecting means with the actual ampacity of the circuit.
I too was a working electrician that recently got tired and retired. I
finally just finished putting the finishing touches on two webpage
calculators that read Table 310.16 and most of the related
requirements. I swear the thing took me about 2000 hours over ten
years. It was a bitch to wite!