JohnF wrote:
"HorneTD" wrote in message
hlink.net...
JohnF wrote:
Thanks for the input. So do I understand this then that I simply install
a
20 amp wall switch at the garage entry point and a panel with 2 pole
breaker? Again thanks.
"HorneTD" wrote in message
arthlink.net...
JohnF wrote:
Sorry I left out key info. The garage is detached and is approx 50'
from the main house panel . It is a 240V line; the wire is #12/3 plus
ground. At the moment only a 120v leg is attached to a 15A receptacle. I
want to use the existing wire that is running from the house to the garage.
Thanks.
John
"zxcvbob" wrote in message
...
JohnF wrote:
John
If the wire is twelve gage then there is no need for any panel in the
garage. Just change the breaker from a thirty ampere to a double pole
twenty ampere breaker. At the garage you install a switch box that will
hold a two pole single throw switch. The black wire goes to one pole of
the switch the red wire to the other pole of the switch with the white
spliced through and the green/bare bonded to the switch strap or yoke.
The switch should be rated for the full twenty amperes but you could use
two separate single pole switches if you preferred. A single two pole
switch is better practice. The switch will serve as the building
disconnecting means and it must be located very close to were the wires
enter the building. The circuit that you will then have is called a
multiwire branch circuit. You are allowed to use two single pole
breakers on that circuit but one two pole breaker is better practice for
residential property. If the circuit will supply a 240 volt load, such
as a large unit air conditioner, in addition to the 120 volt loads then
you must use a two pole breaker to protect it and a two pole switch as
the building disconnecting means. That circuit will give you the
equivalent of two twenty ampere 120 volt circuits without running
another wire. The circuit for your work bench receptacle outlets will
be connected between the white and black and the circuit for the lights
and door opener will be connected between the white and the red. Each
circuit will then have 120 volts with 240 volts between the black and
red. That is what allows the two circuits to share the white neutral.
--
Tom
John
The new two pole, twenty ampere, breaker is installed in the panel at
the house were the circuit to the detached garage originates. You don't
need any new panel in the garage. Just install a switch or switches at
the garage to function as the required building disconnecting means.
--
Tom Horne
Thanks Tom. I am taking 2-pole switch to mean just like a light switch. Am I
then just running the lines from the new 2-pole switch box to the future
garage door opener and work bench? This is certainly an easy and fast way
but without breakers in the garage if a line overloads for some reason I
can't reset from the garage which is what I would like to be able to do.
John
You can have breakers in the garage if you use a small panel at the end
of your twenty ampere feeder but if the overload is caused by the loads
on more than one of the branch circuit breakers in the garage it will
still trip the feeder breaker back in the house panel. With the feeder
having a capacity of twenty amperes installing a sub panel in the garage
is not worth the work involved. If you do install a sub panel you have
to build a Grounding Electrode System for the garage. With only a
single multi-wire branch circuit a grounding electrode system is not
required.
Someone else has suggested that you use an air conditioning disconnect
as the garage building disconnecting means. The problem is that the
building disconnecting means must be "suitable for use as service
equipment" and most air conditioning disconnects are not. The exception
to that rule allows the use of "snap switches", which is the code
language for an ordinary toggle switch, but that exception does not
permit the use of other types of switches or pullouts that are not
"suitable for use as service equipment." The exception is only meant to
permit the use of snap switches for residential outbuildings. If any
more elaborate disconnect is needed then the device used must be listed
by an electrical testing laboratory and marked "suitable for use as
service equipment."
--
Tom H
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