Running Cat-5 and Telephone cables along side AC?

Running Cat-5 and Telephone cables along side AC?

Post by Sam Manso » Thu, 24 Jul 2003 22:46:19



Is it ok to pull cat-5 and telephone cable through the same holes in the
rafters and the wall to utility room as the 110 AC is running? This is a home
installation not a business. They are pulling two cat-5 and two
telephone lines to pretty much every room in the house from a utility room in
the ba*t.

Thanks.  

 
 
 

Running Cat-5 and Telephone cables along side AC?

Post by Macy Hallo » Thu, 24 Jul 2003 23:12:33



+---------------

Quote:> Is it ok to pull cat-5 and telephone cable through the same holes in the
> rafters and the wall to utility room as the 110 AC is running? This is a home
> installation not a business. They are pulling two cat-5 and two
> telephone lines to pretty much every room in the house from a utility room in
> the ba*t.

It's not good practice, though I've seen it done many times without
negative effects.  Best practice is to drill sepeates 1/2" or 3/4" holes
for low volatage cable acess  with 12" or more separation from AC where
possible.

Don't forget you're not allowed to overfill any access hole with cables.
I forget the exact rules, see NEC for details.

In many areas the local inspectors flat out won't allow it, they'll insist
that low voltage and high voltage cables run in different paths.
--
+ Macy M. Hallock, Jr. + APK Net + Tel:216.241.7166 + Fax:216.241.7522 +
+  Speaking for myself. Anyone who agrees may need professional help.  +
--
 Macy M. Hallock, Jr. - APK Net - Tel:216.241.7166 - Fax:216.241.7522

 
 
 

Running Cat-5 and Telephone cables along side AC?

Post by Dr. Anton Squeege » Fri, 25 Jul 2003 00:05:52



Sam Manson says...

Quote:> Is it ok to pull cat-5 and telephone cable through the same holes in the
> rafters and the wall to utility room as the 110 AC is running? This is a home
> installation not a business. They are pulling two cat-5 and two
> telephone lines to pretty much every room in the house from a utility room in
> the ba*t.

        Not a good practice, no, and prohibited under at least Washington
state electrical codes.

        If a CAT-5 or similar low-voltage lead needs to cross a power
line, they need to do so at 90-degree right angles. The idea is to
prevent induction between the power lead and the data stuff.

--
Dr. Anton Squeegee, Director, Dutch Surrealist Plumbing Institute
(Known to some as Bruce Lane, KC7GR)
kyrrin a/t bluefeathertech d-o=t c&o&m
"Quando Omni Flunkus Moritati" (Red Green)

 
 
 

Running Cat-5 and Telephone cables along side AC?

Post by Dana W. Smit » Fri, 25 Jul 2003 09:07:54


In a word - No.  NEC 2002 para 800.52.A.1.c. states,  "Communications
conductors shall not be placed in any raceway,..., or similar fitting with
conductors of electric light, power,...."  There are exceptions but you
didn't list any that qualified.  CAT 5 can be used for telephone so call
them the same in this instance.  Telephone cable is still a communications
conductor even if it's POTS.
By running parallel to the electrical service you're setting yourself up for
induced power noise (aka power influence).  Maintain at least 8 inches and
preferably 12 or greater from the power lines.  Any time you cross power
lines try to do so at 90 degrees.
  Now to get off the high horse.  It has (running the cable in the same hole
and parallel to each other, and is being done on a daily basis by
electricians and security system installers.  NEC 2002 para 300.3.C.1 allows
AC and DC circuits of 600 Volts nominal or less to occupy the same space.
Telephone and data are DC circuits right?  At least that's the justification
being used.  The 800.52 reference specifically states communications
conductors and at least in my opinion takes precedence, however check with
the authority having jurisdiction in your area.
I hope this helps.

Dana Smith


Quote:> Is it ok to pull cat-5 and telephone cable through the same holes in the
> rafters and the wall to utility room as the 110 AC is running? This is a
home
> installation not a business. They are pulling two cat-5 and two
> telephone lines to pretty much every room in the house from a utility room
in
> the ba*t.

> Thanks.

 
 
 

Running Cat-5 and Telephone cables along side AC?

Post by James Knot » Fri, 25 Jul 2003 10:21:08



> In a word - No.  NEC 2002 para 800.52.A.1.c. states,  "Communications
> conductors shall not be placed in any raceway,..., or similar fitting with
> conductors of electric light, power,...."  There are exceptions but you
> didn't list any that qualified.

Running under floor boards is not exactly sharing a raceway.

Quote:> By running parallel to the electrical service you're setting yourself up
> for induced power noise (aka power influence).

I doubt the induced 60 Hz noise will have much effect on ethernet running at
several MHz.

Quote:> Telephone and data are DC circuits right?  At least that's the
justification
> being used.

There is DC current on phone lines, but I don't think there is on twisted
pair ethernet.  However, in both cases the signal is definitely AC.

--

Fundamentalism is fundamentally wrong.


james.knott.

 
 
 

Running Cat-5 and Telephone cables along side AC?

Post by Dana W. Smit » Fri, 25 Jul 2003 21:45:16


Sorry James, the reference to raceway was intended for the hole in the
rafters.  I don't know where running under floor boards came from.

A noisy power circuit will induce noise into a parallel run communications
cable.  It's equivalent to a transformer of a single winding.  Not effecient
and the further the lines are seperated the more induction is decreased.
The twist in the pairs further reduces the effects of induction.  That's why
over short distances installers are getting away with running them together.
It still doesn't make it right and as we go higher in data rates you're
going to see it makes a difference.

Here's something to ponder - id the jacket surrounding the electrical
conductors considered a barrier?

Have a great day - got to get to work.

Dana Smith


> > In a word - No.  NEC 2002 para 800.52.A.1.c. states,  "Communications
> > conductors shall not be placed in any raceway,..., or similar fitting
with
> > conductors of electric light, power,...."  There are exceptions but you
> > didn't list any that qualified.

> Running under floor boards is not exactly sharing a raceway.

> > By running parallel to the electrical service you're setting yourself up
> > for induced power noise (aka power influence).

> I doubt the induced 60 Hz noise will have much effect on ethernet running
at
> several MHz.

> > Telephone and data are DC circuits right?  At least that's the
> justification
> > being used.

> There is DC current on phone lines, but I don't think there is on twisted
> pair ethernet.  However, in both cases the signal is definitely AC.

> --

> Fundamentalism is fundamentally wrong.


> james.knott.

 
 
 

Running Cat-5 and Telephone cables along side AC?

Post by James Knot » Sat, 26 Jul 2003 10:50:09



> A noisy power circuit will induce noise into a parallel run communications
> cable.  It's equivalent to a transformer of a single winding.  Not
> effecient and the further the lines are seperated the more induction is
> decreased.
> The twist in the pairs further reduces the effects of induction.  That's
> why over short distances installers are getting away with running them
> together. It still doesn't make it right and as we go higher in data rates
> you're going to see it makes a difference.

My point is, that while 60 Hz current may be induced in the ethernet cable,
it's not likely to get past the transformers on the NIC, which are designed
to handle frequencies so much higher (100K - 1M times) that 60 Hz will have
no effect.  IIRC, most of the enery in a 10 Mb ethernet, is around 5 MHz.  
It's much higher in 100 Mb.

--

Fundamentalism is fundamentally wrong.


james.knott.

 
 
 

Running Cat-5 and Telephone cables along side AC?

Post by Joe » Sat, 26 Jul 2003 13:28:12


Quote:> A noisy power circuit will induce noise into a parallel run communications
> cable.  It's equivalent to a transformer of a single winding.

Maybe it will, but to no effect.
 
 
 

Running Cat-5 and Telephone cables along side AC?

Post by Justin Ti » Sat, 26 Jul 2003 15:14:34



Quote:> Sorry James, the reference to raceway was intended for the hole in the
> rafters.  I don't know where running under floor boards came from.

> A noisy power circuit will induce noise into a parallel run communications
> cable.  It's equivalent to a transformer of a single winding.  Not effecient
> and the further the lines are seperated the more induction is decreased.
> The twist in the pairs further reduces the effects of induction.  That's why
> over short distances installers are getting away with running them together.
> It still doesn't make it right and as we go higher in data rates you're
> going to see it makes a difference.

> Here's something to ponder - id the jacket surrounding the electrical
> conductors considered a barrier?

> Have a great day - got to get to work.

> Dana Smith

According to my copy of the NEC, 800-52(a)(2) states the separation
must be "a continous and firmly fixed nonconductor, such as porcelain
tubes or flexible tubing, in addition to the insulation on the wire."
It appears the argument the insulation acting as a barrier is not
enough for code purposes.
 
 
 

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