Re: Inspections: (was Re: mixed voltages in Altronix ALTV244 box)

[Marc F Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On Mon, 5 Dec 2005 08:44:18 -0500, "Robert Green" <ROBERT_GREEN1963@xxxxxxxxx>
wrote in message  <-MOdnU-R54X02QnenZ2dnUVZ_sGdnZ2d@xxxxxxx>:

>"Marc F Hult" <MFHult@xxxxxxxxxxxxxxxxxxxxx> wrote
>
><stuff snipped>
>
>> IMO, what folks that do their own home automation and other low voltage
>> installations in the US and Canada need to grok is that the NEC, NFPA, UL
>and
>> ULC address fire and electrocution prevention.
>
>Agreed.  Even OSHA has standards:
>
>_______________________________________________
>
>Design Safety Standards for Electrical Systems: Special Systems -- OSHA
>Standard 1910.308 1
>
>1910.308(c)(1) -- Classification. Class 1, Class 2, or Class 3 remote
>control, signaling, or power-limited circuits are characterized by their
>usage and electrical power limitation which differentiates them from light
>and power circuits. These circuits are classified in accordance with their
>respective voltage and power limitations as summarized in paragraphs
>(c)(1)(i) through (c)(1)(iii) of this section.
>
>(i) -- Class 1 Circuits
>
>(A) -- A Class 1 power-limited circuit is supplied from a source having a
>rated output of not more than 30 volts and 1000 volt-amperes.
>
>(B) -- A Class 1 remote control circuit or a Class 1 signaling circuit has a
>voltage which does not exceed 600 volts; however, the power output of the
>source need not be limited.
>
>(ii) -- Class 2 and Class 3 Circuits
>
>(A) -- Power for Class 2 and Class 3 circuits is limited either inherently
>(in which no overcurrent protection is required) or by a combination of a
>power source and overcurrent protection.
>
>(B) -- The maximum circuit voltage is 150 volts AC or DC for a Class 2
>inherently limited power source, and 100 volts AC or DC for a Class 3
>inherently limited power source.
>
>(C) -- The maximum circuit voltage is 30 volts AC and 60 volts DC for a
>Class 2 power source limited by overcurrent protection, and 150 volts AC or
>DC for a Class 3 power source limited by overcurrent protection.
>
>(iii) -- The maximum circuit voltages in paragraphs (c)(1)(i) and (c)(1)(ii)
>of this section apply to sinusoidal AC or continuous DC power sources, and
>where wet contact occurrence is not likely.
>
>1910.308(c)(2) -- Marking. A Class 2 or Class 3 power supply unit shall be
>durably marked where plainly visible to indicate the class of supply and its
>electrical rating. (See 1910.302(b)(3).)
>
>______________________________________________
>
>I assume these are very much like the NEC and UL requirements.  Since you
>clearly are an expert in the low voltage code requirements, can you tell me
>what they consider as a "Class 1 remote control circuit?"

Yikes! An 'expert' in Code matters I am decidedly not ! ;-)

(I'm a scientist, not a regulator, but know enough about some parts of federal
environmental laws and regulation to have a sense of what constitutes being an
'expert' in regulatory matters. )

A few months ago I posted a url to the draft 2005 NEC. It may still be
available through waybackmachine.org It is also available for purchase for
~US$150 and will eventually be available at your local library.

Later ... Marc
Marc_F_Hult
www.ECOntrol.org