Max Lenght of Coaxial Cable

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PWR73

Member
I took my test JM last week, missed it by one point. This question threw me. In a CCTV system what is the maximum length allowed for a coax cable. 500, 700, 800 or 1000?

Anyone know this I cant seen to find the code article?
 

A/A Fuel GTX

Senior Member
Location
WI & AZ
Occupation
Electrician
That answer doesn't exist in the NEC. I know you can run some pretty long home runs with RG 6 in excess of 300' without any signal degradation but the max length???? Good question.
 
M

mkoloj

Guest
2 Questions:
What kind of coax?
How much do you have on the spool?
 

dereckbc

Moderator
Staff member
Location
Plano, TX
The correct answer was:
e. None of the above.

This is not a NEC issue and the answer completely dedends on the type of coax, type of signal, signal stregth input, receiver input sensitivity, etc..
 
PWR73 said:
I took my test JM last week, missed it by one point. This question threw me. In a CCTV system what is the maximum length allowed for a coax cable. 500, 700, 800 or 1000?

Anyone know this I cant seen to find the code article?

Not a code issue, but this may help:

http://www.pelco.com/support/videosecbasics/selectingcable.aspx

In the average CCTV installation, with cable lengths of less than 750 feet (228 m),RG59/U cable is a good choice. Having an outside dimension of approximately 0.25 inches, it comes in 500-and 1,000-foot rolls.

For short cable runs, use RG59/U with a 22-gauge center conductor, which has a DC resistance of about 16 ohms per 1,000 feet (304 m). For longer runs, the 20-gauge variety which has a DC resistance of approximately 10 ohms per 1,000 feet will work well. In either case, cables with polyurethane or polyethylene as the dielectric material are readily available.

For installations requiring cable runs between 800 (244 m) and 1,500 feet (457 m),RG6/U is best. Having the same electrical characteristics as RG59/U, its outer dimension also is about equal to that of RG59/U.RG6/U comes in 500-,1000-and 2000-foot rolls, and it may be obtained in a variety of dielectric and outer-jacket materials. Due to its large-diameter center conductor of about 18 gauge,RG6/ U has a DC resistance of approximately 8 ohms per 1,000 feet (304 m) and can deliver a signal farther than RG59/U.
 
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