---------- Forwarded message ----------
Date: Sat, 8 Mar 2008 18:05:10 -0500
From: Heath Roberts <htroberts@...>
To: EntertainmentElectricity@yahoogroups.com
Subject: Re: [EntertainmentElectricity] 120VAC over microphone cable?!?

My response might be too late for this situation, but I don't think anyone
has quoted chapter & verse, so I'll add my two cents for future reference:
As others have pointed out, NEC Art 520-68 requires 'extra hard service'
cables for portable power distribution in entertainment venues.
Additionally:
--Art 210-7(f) says that you can't use connectors of a given type for more
than one voltage, frequency, or type of current (AC or DC) within the same
premise. So, other reasons to avoid the practice notwithstanding, you could
only use an XLR for 120vac if no other systems use the same connector.

--Although I can't find an NEC article that requires listed wiring devices,
I think it's in there somewhere--no AHJ I've ever worked in would allow
devices that aren't listed. I've never seen an XLR connector that was listed
for AC power. [this appears to be covered under Art 110-2 and 110-3, which
require that equipment be "approved" by the AHJ. That effectively means it
has to be listed.]

--it's just bad practice to do wire equipment in a way that's not obvious to
the user (like, for example, making up your own color code, or using
connectors for voltages other than what they're officially designated for. I
think this actually is mentioned in NEC, but I don't see it offhand. If it's
possible to easily do something like plugging a microphone or intercom into
mains power, eventually someone will.


Ask your facility management if they're willing to knowingly accept the risk
of a fire being caused by this "solution". If they are, they're idiots. In
many jurisdictions, if a fire *did* occur and someone who should have known
better didn't prevent this sort of thing, they could well be charged with a
felony, especially if someone dies.


It's hard for me to believe this is common practice in New York, which
generally has pretty stringent requirements for theater spaces, or anywhere
else--can anyone confirm whether this is the case?

Regards,
Heath

On Sat, Mar 8, 2008 at 1:51 AM, Ken Porter <kporter@...>
wrote:

> I've lurked for a while, but I finally have something for which I
> need some more knowledgeable support. This came from a coworker in a
> separate venue, who has a roadshow loading in.
>
> Apparently the tech who came with the show wants to run 120VAC power,
> at 1.1 amps over microphone cable (i.e. 3-pin XLR, typically about 20-
> gauge wire) to run a small motor.
>
> Now my co-worker's, and my instinct is to say "no way". The tech's
> response being "they do it all over the country" and "it's how rental
> gear comes in NY".
>
> There's going to be roughly 100' of this power/control cable, but I'm
> not sure the length is even relevant. Who's bonkers here? If this is
> unacceptable, is it because of the current? the voltage? the distance?
>
> I think the tech may be confused because (I'm led to understand that)
> the equipment in question can be either A) fed 120V @1.1 amp OR B)
> fed a low-voltage control signal separate from 120V power feed. I
> think he's confusing method (B) for method (A).
>
> Can someone point me to some particular pice of NEC code that we can
> show this visiting tech, to put this issue to rest?_,___
>



--
Heath Roberts
htroberts@...