electrical code Arduino

[Karl W4KRL]

Alex,

 

The power switching components in the box (the relay), the wiring to the box
(insulation and gauge), and the grounding of the box should, for you own
sake, conform to the National Electrical Code (NFPA 70). Start by looking at
Article 200.

 

http://classdat.appstate.edu/FAA/TEC/scanlindm/2011%20national%20Electric%20
Code/National%20Electrical%20Code%202011.pdf

 

Compliance should be pretty easy if you use a UL rated relay, UL rated
terminal blocks, and the conductors (wires) from the line through your box
to the load are no larger than the NEC branch circuit conductors (probably
#14) and the wire insulation has a real rating (like Romex or stranded THHN
not electronic hookup wire or speaker wire). Provide approved strain
reliefs. Use approved connectors. Make sure any box you are tapping into is
large enough to accommodate additional wiring and use approved connection
devices.

 

I would terminate the power connections in the box at a 4 by 2-point barrier
strip with the ground having its own point so the ground conductors can be
bolted to each other.

 

The connections to the power circuits should most definitely conform to NFPA
70 NEC. Since you are controlling a motor you might look at Article 430.
Make sure your relay is rated for motor or inductive loads larger than the
motor rating. Remember, starting current is up to five times the running
current. 

 

This is all for your own good. If you choose to ignore the code, don't
bother calling your insurance company if your house burns down or you are
electrocuted.

 

And Mo is right, less than 50V pretty much relies on good engineering and
common sense. Make sure the 120Vac does not get into the low voltage stuff
by design or fault.

 

73 Karl W4KRL

 

From: Alex Fraser [mailto:beatnic at comcast.net] 
Sent: Monday, April 22, 2013 1:24 PM
To: tacos at amrad.org
Subject: Re: electrical code Arduino

 

That's good, but if you use an Arduino to control a house current switching
relay is that still considered low voltage?  A for instance would be the
heating system in my house.  The furnace control board is 24 volt and so are
the solenoid valves, but it gets it's power from the mains (love that term).
Also the circulating motor for the hot water is 110 volt.  Does the code
stop at the black box?

On 4/21/2013 7:35 PM, Mike O'Dell wrote: 

if it's low-voltage (< 48VDC) things are pretty loose
 
   -mo
 






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