[Cob] Re: Cob: electrical

[D.J. Henman]

Air is as I previously mentioned not going to help.   It will be the 
aluminum casing conducting out to the recepticles and out to the 
surrounding cob.    The figure of 9,600 times faster is a mater of 
record and can be verified by looking at the conductivity factor for air 
verus aluminum.   If you wanted you could also try to find a 
conductivity factor for dry packed dense soil and compare it to air.    
I am sure that your electrician is good as what he does, but,  having 
air inside would not help dissipate heat and you are not going to force 
blow air through the conduit to make any difference.

 Having air between wires is a difference matter, in this case you using 
it as an insulation keeping them disconnected and avoiding conduction.    

It will not remove as much as the conduction to the cob.   Give us your 
real  data and I will show you.

What factor are you using for cob's thermal conductivity?      The heat 
is conducting though metal which transfers heat 9,600 times faster than 
air.   The surface area of the whole length of the conduit will be 
dissipating heat into the cob.  

And secondly, you shouldn't be having a heat problem in the first place.

So if you disagree with this give use your cob conductivity factor.  I 
have the factors for aluminum and air.

Darel

----------------------

Dorothy Bothne wrote:

> I think he was worried about uneven heat dissipation, hot spots or 
> areas where the heat would be held around the wires.  (And he does 
> have the credentials - over 30 years designing electrical and lighting 
> systems for commercial and residential buildings.)  The conduits open 
> to the j boxes, and the jboxes are open to the room, so the air can 
> move through the conduits and vent to the room. This would remove any 
> heat build up much quicker than conduction through the cob wall. 
> In the earlier posting, I was referring to pulling wires (#12 green, 
> black and white for 15Amp outlets on a 20Amp breaker) through the 
> conduit not the Romex (much easier to pull wire through the conduit 
> than pulling Romex through it).  Exterior grade Romex (not 
> interior) works great buried in cob, but it's too much trouble if for 
> some reason you have to change out the wire.  You'd have to abandon 
> the romex in the wall and find another way to connect the new wire. 
>  The conduit gives you a little more flexibility if you change your 
> mind about what is connected to the circuit or if the wire goes bad 
> and has to be replaced.  And, you're limited in the wire size that is 
> readily available in the exterior grade Romex.
> Also, I think the wire is a little easier to work with than the 
> Romex.  I've found it pretty easy to route the blue "smurf tube" where 
> I want outlets, lights and switches.  Sometimes pulling the wire 
> through has gotten a little tricky, and the whole system's not 
> connected yet.  I'll post the results to the list when I get the area 
> dried in and connect the electrical panel. 
> I've done all the electrical rough in myself.  The first building I 
> did, I only had to have an electrician help me connect the breaker box. 
> Dorothy
>
>
> David Knowlton <pilot1ab80 at hotmail.com> wrote:
>
>     i have no credentials here, but why would air dissipate heat
>     better than
>     cob? again - no research available. common sense tells me the cob
>     would be a better heat sink than air. romex is extra insulated - the
>     coating is real tough stuff - and if it works in the ground - why not
>     in the 'earth' that is cob? Air is an insulator, solids are better
>     conductors
>     in general. just thinking out loud.
>
>     david
>
>
>     >From: Dorothy Bothne
>     >Reply-To: Dorothy Bothne
>     >To: coblist at deatech.com
>     >Subject: Re: Cob: electrical
>     >Date: Fri, 12 Sep 2003 06:06:31 -0700 (PDT)
>     >
>     >Mary,
>     >I've handled electrical systems in two different ways. In the first
>     >structure I built, I used Romex (available at Home Depot) rated
>     for outside
>     >(direct burying). I buried it directly in the cob. the structure
>     had 3
>     >outlets and 2lights and 1 exhaust fan. everything works fine. I'm
>     >working on my second structure now. I consulted with an electrical
>     >design engineer and he recommended that I use a conduit buried in
>     the wall
>     >and pull the wires through the conduit in lieu of direct burying
>     the Romex.
>     > He also suggested that I use the blue "smurf tube" because it's
>     flexible
>     >enough to bend around curves and you need fewer fittings.
>     >The reason that he said to use conduit is that the wire needs the
>     air in
>     >the conduit to dissipate heat. also, you can replace the wire in the
>     >conduit easier if repairs become necessary.
>     >Dorothy
>     >
>     >Mary Hooper wrote:
>     >Will someone tell me something about installing electrical
>     systems. Do the
>     >wires go outside the wall or are they embedded? that sort of
>     thing. I have
>     >not bought a how-to book yet. This interests me as my honey would
>     not put
>     >an
>     >outlet in the basement (concrete floor) bathroom unless it had a
>     ground
>     >fault interrupter.
>     >The solar panels have to connect to inside somehow. Maybe it's
>     wired like a
>     >"regular" house?
>     >thanks
>     >Mary
>     >
>     >
>     >
>     >
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