On the 50foot rule

[ctoddwilson]

I know you cannot bring an OSP cable inside a building more than 50' unless it is in a metallic conduit. I am unclear if this must be a rigid metal conduit or can this be EMT. Please advise with correct NEC article if known. Also, if I transition to a plenum cable(splice) how far can I enter the building before adding protection.

I am in a highly competetive bid situation. However , I will bid it to code and quote the NEC to back my bid.

Thank you all who can help.

 

[mhulbert]

OK, what's an OSP cable? Are we talking phone company material?

Either way, I've never heard of the 50' rule, please explain. Could this be part of the service requirements with the phone company that serves you?

Mike

 

[celtic]

I'll have to plead ignorance here....what's an OSP cable?

 

[infinity]

Here's some info on OSP:

http://www.superioressex.com/faqs/osp_faqs.htm

 

[celtic]

Thank you...I learn something new here everyday

 

[don_resqcapt19]

We need to know if this is a phone cable, fiber optic cable of something else.
Don

 

[ctoddwilson]

This is a 1200 pair phone cable, pic filled. I'm sorry for not being more clear. I think I get in my own little world and forget not everyone is in it. Thanks.

 

[ctoddwilson]

It is a phone cable. The NEC states that when bringing an un rated Outside Plant Cable (OSP) into a building it cannot run more than 50' to point of termination unless rigid or IMC conduit(I believe). I was hoping someone could tell me exactly where in the NEC this is stated. Thank you for responding.

 

[got_nailed]

Lets try NEC article 800-50, exception 2.


7. Can I run copper OSP cable inside a building?
Outside plant cables are not rated for UL CMR or CMP listing and when used inside buildings the National Electrical Code* requires the cable be placed inside metal conduit (NEC article 800-50, exception 2). In addition to NEC regulations, special state, county and local building/fire codes may apply when engineering projects utilizing this type of cable.
*The NEC allows OSP cable to be extended from the outside a maximum of 50 feet to allow a termination to be made.

 

[bmac71]

I am no expert, but I spent a little time with a large telecommunications company, so I will provide my 2cents.

A 1200 pair phone cable is very large and when we had this size cable entering a building, it entered (underground) on the 1st floor (or basement) telco room. From this point it was terminated into some kind of distribution panel and then fed to each location in the building from the distribution panel. I guess I am wondering how far into the building you are running a 1200 pair cable??

The way I am readin 800.113 (including the exceptions and FPN's) I believe the max is 50' and then it has to be terminated in a enclosure or listed primary protector.

Just my thoughts.

 

[Tourcosta]

Osp

Osp

OSP is OutSide Plant. Typically they would be gel filled and have a thick plastic coating with plastic protectors running through the cable.

I have always used EMT when going more than 50 feet and have never had a problem with an inspection although I don't know where it is in the NEC. You do, however, mention plenum cable. If you are going into a plenum airspace I don't believe that the 50' rule applies i.e. I believe it to be zero feet but, again, I don't know the section.

 

[don_resqcapt19]

The main rule in 800.113 says the cable must be listed and marked if it is to be installed inside of the building. The exception says that up to 50' of unlisted, unmarked cable many be used inside. There is nothing in Article 800 that would permit you to go beyond the 50' even when using conduit. Note this is a change from the 2002 code.
The 2002 code says:

800.50 ...Exception No. 2: Listing and marking shall not be required where the cable enters the building from the outside and is continuously enclosed in a rigid metal conduit system or an intermediate metal conduit system and such conduit systems are grounded to an electrode in accordance with 800.40(B).

The 2005 code says:

800.113 ... Exception No. 2: Listing and marking shall not be required where the length of the cable within the building, measured from its point of entrance, does not exceed 15 m (50 ft) and the cable enters the building from the outside and is terminated in an enclosure or on a listed primary protector.

Don

 

[bmac71]

I agree Don, I thought I read this correct.

I am still confused as to why anyone would want to continue the OSP into a building more that 50' without terminating into a panel. I ask this becausel the telco will only go to the demarcation point not to each room in a building without a charge or service plan and still will not run a 1200 pair that far into a building.

 

[Tourcosta]

OSP Cable

OSP Cable

We have worked in a number of office building where the primary Demarc for the Telco is well within the building. We did a job earlier in the year where the first primary panel was on the fifth floor.

 

[bmac71]

I understand the demarc can be anywhere in the building, but from my experience when I worked for the telco we would try not to extend a 1200 pair to the 5th floor. I say (try not) because I am sure there is a price and options for everything. I was nto aware that it was ever done. But I am sure it is done different in different areas.

 

[ctoddwilson]

Thanks for replying. To answer your question on how far into building-about 65' in one building being fed from another building. About 100' into second building. I was looking for the code to educate my potential customer on why we had to transition to a Plenum cable or add metal conduit. Again, thanks for your reply.

 

[bmac71]

ctoddwilson

Sorry I got 1 track minded there.

I believe you could site 800.154 (A) & (B) for your customer.

 

[bmac71]

ctoddwilson

After reading more into this section, I do not think you need plenum unless you are going to be running in spaces for environmental air or penetrating more than 1 floor.

Per 800.24 the cable can be installed exposed as long as they will not be damaged. But this section also refers to 300.4(D) and 300.11 which provides requirements for installation if there is a possibility of damage. Considering this is communitation cable I would at least run it in conduit.

Hope this helps

 

[don_resqcapt19]

Thanks for replying. To answer your question on how far into building-about 65' in one building being fed from another building. About 100' into second building. I was looking for the code to educate my potential customer on why we had to transition to a Plenum cable or add metal conduit. Again, thanks for your reply

The use of conduit does not permit you to extend nonlisted phone cables more than 50' into the buildind under the 2005 code.
Don

 

[don_resqcapt19]

bmac71,
Nothing in 800.24 changes the requirement in 800.113 that requires the use of listed and marked cable within the building. The outside plant cable is not listed and marked and can olny extend a maximum of 50' into the building.
Don