I want to put a sub-panel in a connected garage. Can I use 6-ga. 3-wire to supply a panel with 4 breakers (20A each)? Do you have to consider the possible use of all of the circuits carrying the maximum load? Thanks!
If in the US you will need 4 wires, 2 hot, 1 neutral, 1 ground. You
put in a breaker in the main panel and that determins the size of the
wire you will need to use. At the sub panel you could most likely
install 10 of the 20 amp breakers if you wanted to. You would not be
able to use all of them at that current as the brakere at the main would
trip first. Similar to most houses. If you total up all the breakers
most likely they will be larger than the main breaker.
Not many are going to use everything at once.
On Tue, 17 May 2016 20:06:14 -0700 (PDT), bob_villain
It can have 4.
Look at your common 100 amp breaker panel - room for 32 breakers -
even at 15 amps each, that's WAY over 100 amps. It's over 200.
Even if it's only an 18 slot panel - the range and drier alone acount
fot 90 amps??? Add cental air for another 20.
That's an odd thing on the terminology. We deal with 3 phase 480.
The underground cable we bury is called quad. One wire is marked as
the ground from the factory. #4 has all the wires the same size. Cable
larger than that has the ground one size smaller than the other three.
Using Opera's mail client: http://www.opera.com/mail/
It's leftover from the pre required-grounding days in the Code when
there was mostly (say) 14/2 or whatever and then there was 14/2 w/g
which, of course, has three wires in the cable but couldn't call that
14/3 'cuz that was already taken for the case w/o ground and so on and
If ground had been required from the git-go, common nomenclature would
likely have been different and just counted the total number...
On Tue, 17 May 2016 18:57:47 -0700 (PDT), bob_villain
It will be overkill if you are installing a 120/240 2/4 slot panel.
That is 40a per phase as Clare said but you do need 3 wire plus ground
(4 wires total) as Dean said.
GE does make that 2/4 panel and I have seen it at about $14 each plus
4 skinny GE breakers.
You do need to consider what the total load of the panel will be at any given time. Will you be running machines constantly or intermittently? You do not have to total up the rating of the individual circuit breakers.
You need four wires for a sub-panel and I think a ground rod for lightning protection is a good idea.
On Thu, 19 May 2016 17:55:31 -0700 (PDT), bob_villain
If you do run that #6 in pretty much anything but Romex, (limited to
the 60c column) you can hang a 60a breaker on it and put in a pretty
nice sub panel. THHN in pipe would be an example of a wiring method
that would get you into the 75c column (65a). At that point I would be
looking at a 6 or 8 slot panel for a few bucks more than that 2/4 GE I
linked the other day.
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