# pulling new wire over existing wire



## 3riverav (Jul 24, 2013)

Working on a commercial remodel  I pulled some coax and cat5 through a conduit which the fire alarm/security company had already pulled their cable through  (cat 5's and 2conductor speaker wires). About 30ft long, with plenty of room in the conduit.  The alarm company is telling the building owner that their cables are potentially damaged and that they will need to run all new wire.  The alarm companies explanation is that cables need to be pulled through the conduit altogether only, because pulling new cable over existing cable will rub the old cable causing issues (i.e the insulation is damaged from the friction).  My thoughts are that if the alarm cables are so easily susceptible to damage from cable friction, they are using poor quality cable that should not be used in the first place.  Aside from the breach of etiquette pulling through someone else' chase, any comments?


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## cda (Jul 24, 2013)

Welcome

Do not have an answer but just wait and someone will post


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## TheCommish (Jul 24, 2013)

it is best to pull munitple wires in a conduit at the same time so as stated they don't rub each other, espicaly if the are bends in the run as all the wires will try to move to the inside of the curve. It can be done, use sufficnat pull lube in a conduit that has plentyof space.


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## globe trekker (Jul 24, 2013)

3riverav,

Also, welcome to the Building Code Forum!



> The alarm company is telling the building owner that their cables are potentially damaged and that they will need to run all new wire.


IMO, I would want absolute verification that the fire alarm conductors are damaged, and that if

they are, that your installation caused the damage. Not sure how one would do that, other than

to remove all conductors from the raceway; not at your expense mind you, and to have an

experienced, forensics RDP to make an evaluation.

If the alarm company is crying foul, I would expect them to pony up all monies to obtain an

independent RDP; one that is agreeable to all parties, and pay for the evaluation "up front".

The results of the evaluation can be discussed afterwards.

*QUESTION # 1:* Do you know what type of fire alarm circuits are in the raceway, ..power

limited or non-power limited?

*QUESTION # 2:* What edition of the NEC is legally applicable to your application?

FWIW, ..if the conductors are removed from the raceway, then you will need to have a

competent representative on the site and actually at the raceway when the conductors are

removed. Also, to have a high quality, working camera present to document, document,

document, document!

.


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## cda (Jul 24, 2013)

maybe??? does not get into wire pulling at same time

760.51 Number of Conductors in Cable Trays and Raceways, and Ampacity Adjustment Factors

(A) NPLFA Circuits and Class 1 Circuits.   Where only non–power-limited fire alarm circuit and Class 1 circuit conductors are in a raceway, the number of conductors shall be determined in accordance with 300.17. The ampacity adjustment factors given in 310.15(B)(3)(a) shall apply if such conductors carry continuous load in excess of 10 percent of the ampacity of each conductor.

(B) Power-Supply Conductors and Fire Alarm Circuit Conductors.   Where power-supply conductors and fire alarm circuit conductors are permitted in a raceway in accordance with 760.48, the number of conductors shall be determined in accordance with 300.17. The ampacity adjustment factors given in 310.15(B)(3)(a) shall apply as follows:

(1)

To all conductors where the fire alarm circuit conductors carry continuous loads in excess of 10 percent of the ampacity of each conductor and where the total number of conductors is more than three

(2)

To the power-supply conductors only, where the fire alarm circuit conductors do not carry continuous loads in excess of 10 percent of the ampacity of each conductor and where the number of power-supply conductors is more than three

also:::

760.133 Installation of Conductors and Equipment in Cables, Compartments, Cable Trays, Enclosures, Manholes, Outlet Boxes, Device Boxes, and Raceways for Power-Limited Circuits   Conductors and equipment for power-limited fire alarm circuits shall be installed in accordance with 760.136 through 760.143.

760.136 Separation from Electric Light, Power, Class 1, NPLFA, and Medium-Power Network-Powered Broadband Communications Circuit Conductors

(A) General.   Power-limited fire alarm circuit cables and conductors shall not be placed in any cable, cable tray, compartment, enclosure, manhole, outlet box, device box, raceway, or similar fitting with conductors of electric light, power, Class 1, non–power-limited fire alarm circuits, and medium-power network-powered broadband communications circuits unless permitted by 760.136(B) through (G).

Jackets of listed power-limited fire alarm cables do not have sufficient construction specifications to permit them to be installed with electric light, power, Class 1, non–power-limited fire alarm circuits, and medium-power network-powered broadband communications cables. Failure of the cable insulation due to a fault could lead to hazardous voltages being imposed on the power-limited fire alarm circuit conductors.

(B) Separated by Barriers.   Power-limited fire alarm circuit cables shall be permitted to be installed together with Class 1, non–power-limited fire alarm, and medium-power network-powered broadband communications circuits where they are separated by a barrier.

also:

760.48 Conductors of Different Circuits in Same Cable, Enclosure, or Raceway.

A Class 1 with NPLFA Circuits.   Class 1 and non–power-limited fire alarm circuits shall be permitted to occupy the same cable, enclosure, or raceway without regard to whether the individual circuits are alternating current or direct current, provided all conductors are insulated for the maximum voltage of any conductor in the enclosure or raceway.


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## Dennis (Jul 24, 2013)

Without respect to the legal aspect of the install the problem is unlikely but the friction from pulling the wires in the conduit with existing wires could burn the insulation off the other wire.  It may be a large conduit but it would be unlikely you could pull the wires in it without burning the insulation.


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## Builder Bob (Jul 24, 2013)

the problem may be with creating an electromagnetic field which causes a false "earth " ground on fire alarm wiring...... thus the FA Control Panel always shows a "fault" which makes fire inspectors unhappy...

article for you to review..

How To Troubleshoot a Fire Alarm System Ground Fault In Half The Time : Commercial Fire Alarm|Houston Fire Alarm Company|Fire Safe and Life Safety Systems


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## electriclese (Jul 28, 2013)

Builder Bob said:
			
		

> the problem may be with creating an electromagnetic field which causes a false "earth " ground on fire alarm wiring...... thus the FA Control Panel always shows a "fault" which makes fire inspectors unhappy...article for you to review..
> 
> How To Troubleshoot a Fire Alarm System Ground Fault In Half The Time : Commercial Fire Alarm|Houston Fire Alarm Company|Fire Safe and Life Safety Systems


I dont see that as an issue with coaxial / cat5 as a source for emi inducted currents.


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## BSSTG (Jul 29, 2013)

Greetings,

Sound like rubbish to me. I've done it many times without incident as long as the pipe is lubed up accordingly.

BS


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## Msradell (Jul 31, 2013)

Code doesn't require it but in most places it' s standard practice to have any fire alarm circuits and separate conduit instead of mixing it with other circuits.


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