Telcos that are already in the POTS and ADSL business and are planning to get into the Triple Play business periodically approach me for advice. They are looking for problems that they will encounter that affect bandwidth, and want to know what problems the field technician would encounter when installing and maintaining the copper infrastructure for TV service that did not affect POTS and ADSL.

Keep in mind that The Triple Play provides 3 quality services over paired 2 copper conductors, and copper infrastructure problems affect all 3 services. It may not be readily apparent on POTS but all bandwidth services are affected.

Problems are many, and I will discuss a few of the most significant challenges. However, I will begin by saying that when customers complain of service problems, I believe that, on average, 50% of the complaints should never be dispatched to the field. There are a myriad of platform problems including provisioning errors, plus hardware and software issues with vendor equipment.

My area of expertise is the copper infrastructure and dirty power in the residence. When a field technician is dispatched, the root causes are many and all too often the field technician works on the effect of the problem and not the root cause. Below I have listed some of the big hitters that affect bandwidth.

PROBLEM #1: Installing bandwidth circuits next to vacant cable pairs with hard trouble
An example of this would be an ADSL customer is on pair #5 and a POTS customer is on pair #6. The tip side of pair #6 is pinched in a pedestal, creating a solid tip ground on the pair. The POTS customer is transferred to pair #10, restoring service, but AC harmonics present on the ring that are not cancelled by the tip because it is grounded interferes with bandwidth on the ADSL customer on pair #5.

Rule: Do not put bandwidth circuits in a sub-unit of cable that has hard trouble on vacant pairs.

PROBLEM #2: Cable pair faults
Any bandwidth cable pair must be free of any DC type faults. When testing a vacant cable pair, DC volts must be 0VDC tip to ground and ring to ground.

Resistance tip and ring to ground must be greater than 20 Megohms. Customer equipment will show a short on a cable pair typically 1.8 Megohms to 3 Megohms. When the customer equipment is disconnected, any short on the pair more solid than 20 Megohms should be located and repaired.

The capacitive balance of the cable pair should be greater than 98%.

Any split cable pair must be identified, located, and repaired.

PROBLEM #3: Bonding and grounding issues
Noise in the copper infrastructure drastically affects bandwidth. One area that I worked that was being provisioned for The Triple Play showed impulse noise greater than -40dBm on all cable pairs leaving the remote. There is always impulse noise on copper circuits, but as long as it is less than -40dBm it has little effect on bandwidth.

There were 5 distribution cables involved, and no matter where we tested -- at the remote, at the customer, or at any pedestal -- we were taking over 200 hits per second at -25dBm. A visual inspection of the pedestals showed either no bond, or a series resistance in the bond because the bond was too loose or too tight.

All bonds should be torqued from 30 to 40 inch pounds. If the bond is torqued to more than 40 inch pounds it stretches the bolt, putting series resistance into the bond. The bond for each cable should be individually attached to the pedestal bond bar for current testing with a clamp on ammeter.

Proper bonding and grounding reduces Power Influence to an acceptable level of less than 80dBrnC. Continuous bonding reduces ingress of interferers above 1kHz such as AM radio, Ham radio, Short Wave radio, and FM radio, and a myriad of other high frequency interferers.

Remember: The telephone cable shield must be attached to the distribution power neutral a minimum of 4 times per mile.

PROBLEM #4: The Network Interface Ground
The National Electrical Code (NEC) places the burden of placing the power ground electrode and providing access for grounding other systems such as the Network Interface Ground to the power ground electrode.

The low voltage technician must connect the Network Interface Ground using #6 coated ground wire. The 2012 NEC code states that #10 and #14 ground wire is no longer acceptable. The ground must test from 0 ohms to 25 ohms and no more. Remember to disconnect any drop shield before testing the Network Interface Ground.

A difference of potential between the power ground and the Network Interface Ground is a huge bandwidth problem. Modems retrain and loose speed, set-top boxes drop, and TVs freeze and pixelate.

PROBLEM #5: Drop wire and inside station wire
Standard Category 3-type wire is acceptable for POTS and ADSL inside station wire and drop wire, but Category 5-type wire should be used for The Triple Play. Category 5 wire drastically reduces ingress of any interferers.

Signing off
If you plan on getting into the Triple Play business, address the above-listed problems up front, be proactive in maintaining the copper infrastructure for that Last Mile, and your move into the Triple Play arena will be successful and profitable. And always feel free to contact me with questions or to offer a tip or correction to my advice. I’d love to hear from you. Contact me at email dmccarty@mccartyinc.com or telephone 831.818.3930.