[Build] Next: Dirty Shop

jim jim at well.com
Mon Jun 28 12:13:58 PDT 2010


thanks, sean. my comments interspersed: 

On Mon, 2010-06-28 at 11:26 -0700, Sean Glang wrote:
> Hi all, first time emailer to this list.
> 
> I wanted to pipe in that in typical electrical wiring schemes, black
> wires are reserved for one phase, and red are reserved for the second
> phase.  If that is the case, 
JS: that is the case. 

> its not a good idea to put all your heavy loads (like power tools) on
> one phase and all your light loads (like lighting... heh) on the
> other.  This creates load imbalance, can cause load on your neutral,
> and violates electrical code.   
JS: power tools, while drawing a lot of current, are used 
sporadically, probably fair to say rarely. lights consume 
a fair amount of current and are on for hours at a time. 
other receptacles are used mainly for powering computers 
or running electronic equipment (soldering irons, scopes...). 
   the electrical wiring currently in place is as i described 
(black for receptacles, red for lights and appliances), so 
the proposal for the shop just extends that convention. the 
reasoning for sticking with that convention is consistency: 
in a hacker space, people may have the moxie to try things 
they don't know much about (hacking); consistency gives them 
a fighting chance of succeeding without bringing down the 
house. 
   as to load imbalance, generally a black, white, and red 
have been pulled together (black always from the "left" 
side of the transformer, red always from the "right", 
therefore out of phase). the white is a common return from 
devices on both the black and red. 
   for example: if just devices on the black are running, 
the white returns the current delivered on the black. if 
some devices on the red are also running, the current on the 
white is reduced to the difference between the current on 
the black and that on the red. assuming no overload on any 
circuit, there is no problem with an imbalance between red 
and black power use. the system (and the electrical code) 
allow (actually assume) this. 


> To keep your lighting safe from tripping along with your radial arm
> saw, simply put it on a seperate circuit.  
JS: the convention of red for lights and black for 
receptacles ensures lights will be on different 
circuits (the primary reason for the convention--
again, the rule is to help ensure that hackers will 
do the right thing). 

> For extra super added safety, put that circuit in a different load
> center.  
JS: the space has several different sub-panels (load 
centers), each serving specific areas. the primary 
benefit seems to be an efficiency in running pipes 
and wires. the current lighting distribution has 
some general purpose lights for the entire space 
coming from one of two main sub-panels and lights 
for specific areas coming from dedicated sub-panels. 
this provides some diagnostic convenience, given the 
community using the space. 

> 
> That's all for now, but i'd like to help out when I get back to
> california. 
JS: great! there's sure to be work remaining. 

> 
> Cheers,
> Sean is.
> 
> > On Jun 28, 2010 10:33 AM, "jim" <jim at well.com> wrote:
> > 
> > 
> >   i bought electrical stuff for the dirty shop,
> > some of which (i hope) is sitting on the top of
> > the dedicated sub-panel, some of which is in the
> > storage-rack room.
> >   the idea is to power all shop lights and
> > outlets from the sub-panel:
> >   * run conduit from the sub-panel around the
> > perimeter of the interior, probably up near the
> > tops of the walls, dropping pipe down at
> > various locations to provide outlets and
> > switches.
> >   * outlets would be of two types: general
> > purpose and dedicated. general purpose are
> > duplexes for light-load hand tools. dedicated
> > are single receptacles for higher amperage,
> > in-place tools (e.g. radial arm saw...).
> >   * lights should be reconfigured, maybe use
> > some of the existing flourescents but re-hang
> > them in best locations, maybe install some
> > fixtures to provide spot lighting for work
> > areas.
> >   * switches can be distributed so's to
> > control work area as well as general lights.
> >   * there's the idea of having an emergency
> > shutoff switch, too, possibly one for each
> > dedicated receptacle and one for each general
> > purpose circuit.
> >   * probably good to redo the power track
> > so's to drop receptacles on cords for use
> > at the table(s) in the center of the room.
> > this might entail rehanging one or more
> > tracks and certainly rewiring so's to power
> > the tracks from the dedicated sub-panel
> > rather than from the primary sub-panels that
> > are currently powering them.
> >   * note policy is to use "black" circuits
> > for all receptacles and "red" circuits for
> > lights and built-in appliances. the point is
> > to keep lights separate, as the likelihood
> > of short-circuits is with receptacles: if
> > there's a short-circuit, it's good that the
> > lights will still be on.
> >   * i'm willing to help, including consider
> > alternate ideas. i don't want to do all the
> > work; i hope for help. probably i'm the one
> > to install the conduit and junction boxes
> > and others are the ones to pull wires,
> > install receptacles and switches, hang
> > lights.... this division of labor worked
> > pretty well with the darkroom (biggest
> > problem there was coordinating differing
> > schedules).
> > 
> > 
> > 
> > 
> > 
> > On Sun, 2010-06-27 at 22:23 -0700, Ben Kochie wrote:
> > > Nice work on the floors. Next up I would ...
> > 
> 




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