slab-on-grade FREE cabling and networking Helpdesk
 Question by Tom Feliciano posted 04 Oct 2005
This question is similar to the "OSP cable into the building". I have plenum rated cable on a horizontal run that is run into the slab for about the last 30 to 50 feet. Since this is considered a "wet" location, does it require a transition point and a change to OSP rated 4-pair or is there a "fifty foot" rule for this type of occurance?
 Answer by Joseph Golan posted 04 Oct 2005
Dear Tom,

The 50 foot rule has to do with OSP cable running within a building from an entry point, it really doesn't apply to a horizontal run. What the rule says is that no more then 50 feet of unrated cable (not CM, CMR or CMP) can be run from the point of entry into a building. There are exception but again in your case it is not a service feed.

Also transition points or splicing are not part of the standards. (You may call it a consolidation point and follow those guidelines)

My ultimate suggestion is to use a specialty cable that has both OSP water blocking protection as well as a plenum rating for these runs. It will be more expensive but you will eliminate the splice point which could end up being a point of trouble later on. Unfortunitly I am on the road with only a dial-up connection and cannot search the manufacturers for you but inquire about the following manufacturers and I am sure that one of them makes this product (BTW you may be limited to Category 5e as I do not recall hearing about this type of product in a category 6 design yet)

Superior Essex
General Cable

Joseph Golan, RCDD

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