# Distance limits:coax vs ethernet **URL:** \ **Category:** Factual Questions\ **Created:** [June 18, 2003, 3:35am UTC](https://boards.straightdope.com/t/distance-limits-coax-vs-ethernet/182616 "2003-06-18T03:35:04Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![keno](https://avatars.discourse-cdn.com/v4/letter/k/f9ae1b/32.png) [@keno](https://boards.straightdope.com/u/keno)\ **Post date:** [June 18, 2003, 3:35am UTC](https://boards.straightdope.com/t/distance-limits-coax-vs-ethernet/182616/1 "2003-06-18T03:35:04Z")
I’m installing a cable modem and have to making a run of roughly 45-ft. Should I make it: (a) 45’ of coaxial cable from cable split to modem, with a 1’ USB connection from modem to computer, or (b) 6" coax cable from cable split to modem, with a 45’ ethernet connection from modem to computer? Is coax or ethernet better at spanning this distance, or is there no difference? What about degradation of cable signal if I split the signal more than once? ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [June 18, 2003, 3:39am UTC](https://boards.straightdope.com/t/distance-limits-coax-vs-ethernet/182616/2 "2003-06-18T03:39:37Z")
Go with the coax (preferably RG-6 or RG-6QS), the reason being is that sort of cable is well designed for its purpose, whereas long runs of CAT-5 or CAT-5e cable can pick up bandwidth-robbing noise in some circumstances. Take the run off the first split from the dropline from the streetside pole. ---
**Author:** ![NormanConquest](https://avatars.discourse-cdn.com/v4/letter/n/7ba0ec/32.png) [@NormanConquest](https://boards.straightdope.com/u/NormanConquest)\ **Post date:** [June 18, 2003, 4:49am UTC](https://boards.straightdope.com/t/distance-limits-coax-vs-ethernet/182616/3 "2003-06-18T04:49:20Z")
Related, but [hijack]: What’s the deal with ratings for ethernet cables? I’ve seen CMR and CMX. I’m wanting to buy some Cat-5e, but I’m wondering about the ratings. > [@](#): > > From [Compgeeks.com](http://Compgeeks.com): > CMX Rating Notes: > CMX (residential) cables may be used only within 1 or 2 family dwellings. > It may not be used for any commercial installation. . “May not”? That implies that it can, but isn’t permitted to… my questions are: Who rates this? Is CMR a higher quality cable with more shielding? If I knowlingly used CMX cable in a commercial installation, would I get in trouble? Would the cable police come looking for me? Do they perform audits or something? ---
**Author:** ![tastycorn](https://avatars.discourse-cdn.com/v4/letter/t/bcef8e/32.png) [@tastycorn](https://boards.straightdope.com/u/tastycorn)\ **Post date:** [June 18, 2003, 5:41am UTC](https://boards.straightdope.com/t/distance-limits-coax-vs-ethernet/182616/4 "2003-06-18T05:41:22Z")
Well, cat 5 cable is certified to run at least 100 meters, so 45 feet shouldn’t theoretically be a problem. The problem arises during bad installation. You can’t have bends smaller than a 5 inch diameter (no kinks), and it is common to pick up interference from florescent lights. How familiar are you with cable termination? Both can be a bit tricky if you don’t know what you are doing. Purchasing a 50 ft length of terminated cat 5 might be the better route as long as you are careful in the installation. ---
**Author:** ![Daver914](https://avatars.discourse-cdn.com/v4/letter/d/4da419/32.png) [@Daver914](https://boards.straightdope.com/u/Daver914)\ **Post date:** [June 19, 2003, 6:30pm UTC](https://boards.straightdope.com/t/distance-limits-coax-vs-ethernet/182616/5 "2003-06-19T18:30:01Z")
As far as I know, CMX and CMP differ only in the material used for casing. CMX (non-plenum rated) uses a PVC coating that is cheaper to make. CMP is what’s called plenum-rated cable (a plenum is the space above the ceiling, by the way, that’s used for ventilation ducts and running wire in a lot of offices). The reason you have to use plenum-rated for commercial jobs is because its casing is not made of PVC, and if there is some kind of a fire it will not give off toxic fumes as it burns which could be spread through the ventilation ducts, as PVC is liable to do.