The following sketch illustrates a strand supporting a single CATV coax cable: Telephone and other communications cables are supported in the same manner. Following are photos of a few representative examples. It also supports: Primary distribution. Secondary distribution. CATV cables. Telephone cables. Traffic signals. Traffic signal wiring.
The secondary distribution wiring appears to be a duplex bundle in which the MGN serves as both neutral and mechanical supporting strand.
A duplex bundle is normally used in situations where only a single volt circuit is required; such circuits are typically provided for low-capacity loads such as streetlights and traffic signals. Note that the fire-alarm wiring is open wire, and that it appears to be very close to the CATV cable. If these wires are not insulated, this would constitute a violation of the National Electrical Safety Code.
When this picture was taken, this pole supported what the National Electrical Safety Code calls a seasonal decoration. Seasonal decorations often contain lighting circuits; these circuits are usually fed from the secondary distribution circuits on the pole. Prestressed concrete poles are often used in coastal areas subject to atmospheric corrosion one manufacturer claims that "concrete poles are foremost in appearance, durability and maintenance-free service".
A riser is an electrical connection attached to the side of a pole; hence, a pole supporting a riser is called a riser pole. The riser provides a connection between aerial conductors and underground conductors. The riser conductors are usually protected by conduit, although a U-guard is sometimes used. This particular concrete pole supports: Static wire. A three-phase wye-connected four-conductor transmission circuit. A three-phase primary distribution circuit, tapped to feed, via the riser, an underground circuit to a nearby large customer such as a school, hospital, or shopping center.
A streetlight. A single-phase secondary distribution circuit fed from a transformer offscreen to the right whose sole purpose is to provide power for the streetlight. Strand-supported CATV cable. Single-phase secondary electric distribution. Pole-mounted CATV power supply. Pole-mounted electric meter to provide power for the CATV power supply.
CATV networks also called broadband networks incorporate broadband amplifiers spaced throughout the network at intervals of about feet. These amplifiers require operating power; this power at 60, 75, or 90 volts RMS is provided by a CATV power supply similar to the one shown here, and delivered to the amplifiers over the CATV network itself.
Each power supply is capable of powering a group of 10 to 20 amplifiers located within a radius of a mile or so. Each amplifier incorporates a DC power pack that rectifies this voltage and provides DC operating voltages for the amplifier circuitry. The CATV power supply receives its operating power from the power company's secondary distribution circuit, at volts, 60 Hz. Depending on the power company's billing policies, CATV power supplies may be metered, or they may be billed on a flat-rate basis.
The power supply illustrated here is metered; the meter is visible below the power supply. It's probably a voice- and data-communications cable owned by a telephone company. The pole attachment clamp supports the fiber in a padded cylinder so that wind-induced vibrations do not cause the fiber to scrape against metal.
The red plastic sleeve above the clamp identifies the name of the owner and provides a contact telephone number. Single-phase triplex secondary electric distribution. Multipair telephone cable. Electric meter behind the sign to meter the power used by the two cable TV power supplies.
Flashing amber warning light. Disconnect switch for the unmetered flashing amber light. In a typical stand of timber, only 7 percent of the trees have the qualities needed to make a utility pole. They are then harvested and transported to manufacturing with trailers specifically designed to accommodate the longer timber. Once at the yard, the bark is removed from the full length of the tree and the pole is shaped to make it straight as possible.
Each pole is reviewed, graded and assigned a class as defined in the ANSI standards. The characteristics reviewed include grain orientation, presence of decay, knots and splits. Next, the poles may be incised, bored or conditioned to prepare the wood to receive the preservative. Other holes for hardware on the pole are bored, maintaining the protective envelope by allowing treatment to penetrate all openings.
Each pole is then branded and tagged, then stacked for treating. To ready wood poles for treating, they must be seasoned or conditioned in a way that maintains strength characteristics. Poles may be air and kiln dried, similar to what is done in drying lumber. Poles may also be steamed or Boultonized in a long pressurized cylinder , also called a retort.
Steaming is mostly used for Southern Pine poles, however Douglas Fir poles treated with water-borne preservatives also may be steamed. Douglas Fir is typically Boultonized, where the retort is pressurized and the preservative is heated to degrees to degrees F. ANSI standards also require sterilization, specified as heating the pole to reach at least degrees F at the center of the pole for at least an hour. The preserving process begins after poles are loaded onto carts and moved into a retort, which can be as long as feet.
The wrong distribution of a load especially a long heavy one like a load of poles can damage a trailer or even cause an accident. With tag-a-long pole trailers, drivers must be especially careful when calculating tongue load: too much weight could damage the tongue hitch , while too little could cause the trailer to wander or even fishtail.
Since the gross vehicle weight G. For example, if the tongue can carry 4, lbs. W of 16, lbs. The Department of Transportation DOT also has requirements for transporting utility poles on public highways.
Depending on what chemicals were used, poles may be recycled, taken to lined landfills, or dropped off at unlined landfill facilities. Eventually, the poles were also used to facilitate cable television and internet services. So, while generally called telephone poles, these poles do a lot more than just support the telephone network. A better name for them is perhaps utility poles — which is what some people already call them. The repair costs are immense, as is the disruption for people living nearby.
By relocating lines to protected tunnels below the earth, some think we could tidy up the nation and safeguard our utilities network. The cheapest is open trenching. This involves digging into the earth, laying down large stretches of cabling and backfilling the trenches later. None of which is usually welcomed by the communities affected.
The second approach is called directional drilling. This approach — a new take on an old technique for drilling oil and gas — is much less invasive.
However, this approach is incredibly expensive.
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