[Noisebridge-discuss] Fwd: Power to the peeple

Wed Nov 10 04:31:18 UTC 2010

answers interleaved below 


On Tue, 2010-11-09 at 12:06 -0800, meredith scheff wrote:
> Heya Noisebridge, 
> This here is my pal Joshua. He's a super cool cat putting a hot tub in
> his back yard, and needs a little electrical knowledge. Can anyone
> help? 
> His email is joshua at nowhereville.org, But I'll foward answers here,
> too.
> m
> 
> 
> Right on.
> 
> 
> So the story is I got a 6' redwood hot tub for nothing. I'm getting a
> control pack and heater for about the same. Which is good, because
> nothing is about how much I have. But I have a dream. And it involves
> hot water. I've gotten the tub, and assembled it, truing some beams,
> etc etc. I've verified that with water it swells up and (mostly)
> seals; I've learned from a boatbuilder friend how to pay and caulk
> wood, etc, which has been fun. I'm about to run the suction joints and
> cap them off and actually fill it and see if it holds water, or more
> likely, how much it leaks. Ahem.  
> 
> 
> So what I have to do is run 220 to my back yard. It's about 70' total,
> the first half of which is in a garage w/ exposed wooden beams, the
> latter half of which I will trench in a yard. Intervening is about 10'
> of concrete, not sure how to cross that yet and stay within code for
> max turn radius/etc. 
> 
> 
> I figure I will drop in a 50A 220V circuit into my current box, run it
> to an elbow at the back edge of the garage (hole already exists),
>  then put it in some type of water-resist flex conduit and run it
> around and bury it, putting in a breaker box at the back. Build a
> little cover for the guts of the spa. Etc. 
> 
> 
> I have questions I figure a knowledgeable electrickal-person can
> answer. If you can tell me anything, I'd be really delighted. 
> 
> 
> 1 - I have 100A service, with 2x20A and 2x15A 120 already run. Can I
> put a 50A circuit into this box? The -total- of the breakers would
> then be over 100 (120), but as I read the code this is okay; in the
> same way as I can plug in more than 15A of lights onto a 15A circuit,
> just not turn them all on at once. The circuits are not in heavy use;
> we don't even have a microwave. If not, I guess I need to get the main
> panel upgraded. Not trivial I think, ugh. 
JS: you can run 180 Amps at least. 50 + 20 + 15 = 85. 
check code, probably you'll have to run #4 wire, one red 
and one black. 
> 
> 
> 2 - Should I put a ground in the back at the sub panel I put in for
> the tub? Or use the ground all the way back through the main panel? 
JS: more ground is better ground. probably best to run a ground wire 
from the tub to the panel and maybe improve the grounding from the 
panel: i.e. drive in a second (or more) grounding rod and make sure 
the wire from the panel to the grounding rod(s) is #4 or greater. 
> 
> 
> My other questions are mechanical - how to trench, where to mount a
> sub panel, how to run the cable in the garage, and especially how to
> get it over the concrete in the back. And code-related - 18" trench, I
> think, other misc. 
JS: check local code. basically something like an 18 inch deep trench, 
two inches of gravel on the bottom, #80 PVC one inch pipe laid on the 
gravel, then filled with dirt. non-trench areas: if they're covered 
(garage, run one inch EMT from the panel to the inside of the wall 
where the it exits. join it to PVC that goes out the wall and down 
into the trench. I like to use junction boxes rather than couplers, 
especially in joining two different types of pipes and also in 
making right angle turns (down to the trench). 
   either break up the concrete or tunnel under it so the pipe runs
straight from the garage to the water heater. Running it above the 
concrete and conforming to code will be more costly and weird. 
   I assume the water heater is enclosed or otherwise outdoor 
approved with some means for the pipe to join or enter its 
interior. 
> 
> 
> 
> 
> On 8 Nov, 2010, at 22:16 , meredith scheff wrote:
> 
> > run the questions by me, and if I don't know, I'll pass them on to
> > the NB list. 
> > M
> > 
> > On Mon, Nov 8, 2010 at 9:53 PM, Joshua Marker
> > <joshua at nowhereville.org> wrote:
> >                Hey, do you know about electricity? Like, at the high
> >         voltages? I need to run a 220 line and I have some questions
> >         - am concerned about both code and safety.
> >         
> >                I also have a new hot tub controller that has a 12V
> >         line for lights and am thinking about what I could do.
> >         Arduinos are $33!
> >         
> >         --
> >         If God had meant for us to be naked, we'd have been born
> >         that way.
> >               -- Mark Twain
> >         
> > 
> > 
> > 
> > -- 
> > doing stuff and making things
> > ---
> > "The function of all art ... is an extension of the function of the
> > visual brain, to acquire knowledge; ...artists are, in a sense,
> > neurologists who study the capacities of the visual brain with
> > techniques that are unique to them. ." -Semir Zeki
> > 
> 
> 
> -- 
> Virgo: (Aug. 23--Sept. 22) 
> One of your greatest problems is your inability to ignore
> oversimplified, arbitrary, and potentially unsound advice from dubious
> sources. 
> 
> 
> 
> 
> 
> -- 
> doing stuff and making things
> ---
> "The function of all art ... is an extension of the function of the
> visual brain, to acquire knowledge; ...artists are, in a sense,
> neurologists who study the capacities of the visual brain with
> techniques that are unique to them. ." -Semir Zeki
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