I have a small detached shed about 90' from my house that I’m using as a workshop. It has a single 20A outlet (sharing a circuit with my bedroom outlets). I want to upgrade to a 50A subpanel. There is existing ¾" schedule 40 buried conduit between the house and the shed. I know this will be a hard pull for three #6's and a #10, but there is too much cement and brick between the structures to easily run larger conduit. Many of you guys have run shop subpanels, so I was hoping you’d look at this sketch of my plans and share any wisdom you learned from your projects.
Subpanel Tips
- Thread starter rdagger
- Start date
pattenp
Well-known member
At 50A will need #6 Cu for the distance. It will fit in the 3/4" conduit. Your diagram looks fine.
You don't need the exterior disconnect if you use a sub-panel with a main disconnect in it.
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You don't need the exterior disconnect if you use a sub-panel with a main disconnect in it.
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wyliesdiesels
Well-known member
I think the GEC and rods should be connected to the panel not the disconnect. Also, u should have 2 rods! Also u could use 3/4" EMT if u haven't bought ur supplies yet, but of course, 1" would be easier to pull through!
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I added the optional exterior disconnect because I work outside the shed a lot and I like being able to shut off the power from inside or outside. I don’t think the code requires any main disconnects for a sub as long as it doesn’t take more than 6 hand movements to shut off all the breakers.
I could be wrong, but it seems it would be safer to have the rods connected at the exterior switch where power enters the structure. In theory, a static discharge like lightning would go directly from the switch down into the ground. Otherwise, the grounding path could be into the shed, through the subpanel and back out.
I’ll use 2 rods over 6ft apart. How do you connect the rods, just run bare #6 buried in the dirt?
I probably will use the 3/4" EMT instead of the 1" because I don't have a 1" bender. I might use the EMT in the house too instead of the NM because I won't have to buy 2 types of wire and the rest of my house is old RMC.
wyliesdiesels
Well-known member
Yes, a main breaker or disconnect is not required in a sub if there are 6 or less OCPDs. With that being said, each detached building IS required to have a disconnect @ the building regardless of the # of disconnects in the panel! (NEC 225.31) So it may be less work to have a main breaker panel than a separate disconnect on the ext. of the building!
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pattenp
Well-known member
The main reason I suggested the main disconnect in the sub was to save money by not buying a separate disconnect switch and box for the exterior. Also a main disconnect is not needed if the sub has six or less switches to be flipped to shut all the circuits off. 225.33
To me, using a main breaker panel is easier.
To me, using a main breaker panel is easier.
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wyliesdiesels
Well-known member
O. I thought the 6 disconnect rule was only for 'service equip'. Now, if there are 6 or less disconnects in a detached building subpanel, is a main disconnect still required @ the building?
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pattenp
Well-known member
No main disconnected is needed in your example. See 225.31, 32, & 33.
You make a good point, it is overkill and an unnecessary expense. The sub will only have 3 or 4 circuits. Also it may be a code violation to put a disconnect switch at the exterior location because there is a copper water pipe within the switch's 30 x 78 inch workspace.
pattenp
Well-known member
I corrected myself. I said main lug panel and meant main breaker panel. You can use a main lug panel if it has six or less circuits, but I highly suggest just using a main breaker panel.
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wyliesdiesels
Well-known member
Yes, bare #6 would work. Just make sure its not subject to damage. U could actually go with #8 but it would have to be protected with conduit!
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theoldwizard1
Well-known member
If it as a concrete floor, like a garage, GFCI are required.
Thanks, found it: "Garages, and also accessory buildings that have a floor located at or below grade level not intended as habitable rooms and limited to storage areas, work areas, and areas of similar use." (2011 NEC 210.8A-2)
Looks like most rooms (except garage and shed) now require Arc-Fault Circuit-Interrupter Protection:"family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, or similar rooms or areas shall be protected by a listed arc-fault circuit interrupter" (2011 NEC 210.12A)
Concrete floors have nothing to do w/ GFCI requirements. A outbuilding does require GFCI protection.
Here is a copy & paste from the 2011 NEC.
210.8 Ground-Fault Circuit-Interrupter Protection for
Personnel. Ground-fault circuit-interruption for personnel
shall be provided as required in 210.8(A) through (C). The
ground-fault circuit-interrupter shall be installed in a
readily accessible location.
Informational Note: See 215.9 for ground-fault circuitinterrupter
protection for personnel on feeders.
(A) Dwelling Units. All 125-volt, single-phase, 15- and 20-
ampere receptacles installed in the locations specified in
210.8(A)(1) through (8) shall have ground-fault circuitinterrupter
protection for personnel.
(1) Bathrooms
(2) Garages, and also accessory buildings that have a floor
located at or below grade level not intended as habitable
rooms and limited to storage areas, work areas,
and areas of similar use
(3) Outdoors
Exception to (3): Receptacles that are not readily accessible
and are supplied by a branch circuit dedicated to
electric snow-melting, deicing, or pipeline and vessel heating
equipment shall be permitted to be installed in accordance
with 426.28 or 427.22, as applicable.
(4) Crawl spaces — at or below grade level
(5) Unfinished basements — for purposes of this section,
unfinished basements are defined as portions or areas of
the basement not intended as habitable rooms and limited
to storage areas, work areas, and the like
Exception to (5): A receptacle supplying only a permanently
installed fire alarm or burglar alarm system shall
not be required to have ground-fault circuit-interrupter
protection.
Informational Note: See 760.41(B) and 760.121(B) for power
supply requirements for fire alarm systems.
Receptacles installed under the exception to
210.8(A)(5) shall not be considered as meeting the
requirements of 210.52(G).
(6) Kitchens— where the receptacles are installed to serve
the countertop surfaces
(7) Sinks — located in areas other than kitchens where
receptacles are installed within 1.8 m (6 ft) of the outside
edge of the sink
(8) Boathouses
(B) Other Than Dwelling Units. All 125-volt, singlephase,
15- and 20-ampere receptacles installed in the locations
specified in 210.8(B)(1) through (8) shall have
ground-fault circuit-interrupter protection for personnel.
(1) Bathrooms
(2) Kitchens
(3) Rooftops
(4) Outdoors
Exception No. 1 to (3) and (4): Receptacles that are not
readily accessible and are supplied by a branch circuit
dedicated to electric snow-melting, deicing, or pipeline and
vessel heating equipment shall be permitted to be installed
in accordance with 426.28 or 427.22, as applicable.
Exception No. 2 to (4): In industrial establishments only,
where the conditions of maintenance and supervision ensure
that only qualified personnel are involved, an assured
equipment grounding conductor program as specified in
590.6(B)(2) shall be permitted for only those receptacle
outlets used to supply equipment that would create a
greater hazard if power is interrupted or having a design
that is not compatible with GFCI protection.
(5) Sinks — where receptacles are installed within 1.8 m
(6 ft) of the outside edge of the sink.
Exception No. 1 to (5): In industrial laboratories, receptacles
used to supply equipment where removal of power
would introduce a greater hazard shall be permitted to be
installed without GFCI protection.
Exception No. 2 to (5): For receptacles located in patient
bed locations of general care or critical care areas of
health care facilities other than those covered under
210.8(B)(1), GFCI protection shall not be required
(6) Indoor wet locations
(7) Locker rooms with associated showering facilities
(8) Garages, service bays, and similar areas where electrical
diagnostic equipment, electrical hand tools, or portable
lighting equipment are to be used
(C) Boat Hoists. GFCI protection shall be provided for
outlets not exceeding 240 volts that supply boat hoists installed
in dwelling unit locations.
Underline by me.
theoldwizard1
Well-known member
I am not a lawyer.
I am not a licensed electrician.
I look at it from a "practical" standpoint. Any floor "at or below grade" is likely to be a concrete floor.
pattenp
Well-known member
You ought to know that anything you say will be cross examined by us electrical technical lawyers and challenged if we find the slightest opening.
wyliesdiesels
Well-known member
LoL! That's very true! 
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