(1)
General. On systems operating above 2 KV to ground,
the design of the conductors or cables installed in non-metallic conduit should
consider the need for an effectively grounded shield and/or sheath.
(2)
Installation.
(a)
General.
1. Bending during handling, installation and
operation shall be controlled to avoid damage to any of the components of the
supply cable.
2. Pulling tensions
and side-wall pressures of cable should be limited to avoid damage to the
supply cable. Manufacturer's recommendations may be used as a guide.
3. Ducts should be cleaned of foreign
material which could damage the supply cable during pulling
operations.
4. Cable lubricants
shall not be detrimental to cable or conduit systems.
5. On slopes or vertical runs,
consideration-should be given to restraining cables to prevent downhill
movement.
6. Supply, control, and
communication cables shall not be installed in the same duct unless the cables
are maintained or operated by the same utility.
(b)
Cable in Manholes and Vaults
-- Supports.
1. Cable supports
shall be designed to withstand both live and static loading and should be
compatible with the environment.
2.
Supports shall be provided to maintain specified separation between
cables.
3. Horizontal runs of
supply cables shall be supported at least three inches above the floor, or be
suitably protected.
Exception: 220 CMR 126.34(2)(b) does not apply to grounding or
bonding conductors.
4. The
installation should allow cable movement without destructive concentration of
stresses. The cable should remain on supports during operation.
(c)
Cable in Manholes
and Vaults -- Separation.
1.
Adequate working space shall be provided in accordance with
220 CMR
126.32(4)(b).
2. Between supply and communication
facilities (cable and/or equipment):
Where cable and/or equipment is to be installed in a joint use
manhole or vault, it shall be done only with the concurrence of all parties
concerned.
Supply and communication cables should be racked from separate
walls. Crossings should be avoided.
Where supply and communication cables must be racked from the
same wall, the supply cables should be racked below the communication
cables.
Supply and communication facilities shall be installed to
permit access to either without moving the other.
Clearances shall be maintained as specified in 220 CMR 126.34:
Table 1.
Table 1
Minimum Separation Between Supply and
Communications Facilities in Joint Use Manholes and Vaults
|
Phase-to-Phase Supply
Voltage
|
Inches of Separation (Surface to
Surface)
|
|
0, to 15,000
|
6
|
|
15,001 to 50,000
|
9
|
Exception 1: These separations do not
apply to grounding conductors.
Exception 2: These separations may be
reduced by mutual agreement between the parties concerned when suitable
barriers or guards are installed.
(d)
Identification of Cables in
Manholes and Vaults.
1. Cables
shall be permanently identified by tags or otherwise at each manhole or other
access opening of the conduit system.
Exception: 220 CMR 126.34(2)(d) i.
does not apply where the position of a cable, in conjunction with diagrams or
maps supplied to workmen, or other means give sufficient identification.
2. All identification shall be of
a corrosion-resistant material suitable for the environment.
3. All identification shall be of such
quality and located so as to be readable with auxiliary lighting.
4. Where cables in a manhole are maintained
or operated by different utilities or are of supply and communication usage,
they shall be permanently marked as to company and/or type of use.
(3)
Grounding and Bonding.
(a) Insulation shielding of cable and joints
shall be effectively grounded.
(b)
Cable sheaths or shields which are connected to a ground at a manhole shall be
bonded or connected to a common ground.
(c) Bonding and grounding leads shall be of a
corrosion-resistant material suitable for the environment or suitably
protected.
(4)
Fire-proofing. Although fire-proofing is not a
requirement, it may be provided in accordance with each utility's normal
service reliability practice to provide protection from external
fire.
(5)
Communication
Cables Containing Special Supply Circuits. Special circuits
operating at voltages in excess of 400 volts to ground and used for supplying
power solely to communications equipment may be included in communications
cables under the following conditions:
(a)
Such cables shall have a conductive sheath or shield which shall be effectively
grounded and each such circuit shall be carried on conductors which are
individually enclosed with an effectively grounded shield.
(b) All circuits in such cables shall be
owned or operated by one party and shall be maintained only by qualified
personnel.
(c) Supply circuits
included in such cables shall be enclosed in an effectively grounded shield or
shields and shall be terminated at points accessible only to qualified
employees.
(d) Communications
circuits brought out of such cables, if they do not terminate in a repeater
station or terminal office, shall be protected or arranged so that, in the
event of a failure within the cable, the voltage on the communications circuit
will not exceed 400 volts to ground.
(e) Terminal apparatus for the power supply
shall be so arranged that live parts are inaccessible when such supply circuits
are energized.
(f) Such cables
shall be identified and the identification shall meet the pertinent
requirements of 220 CMR 126.34(2)(d).
Exception: The requirements of 220 CMR
126.34(5) do not apply to supply circuits of 550 volts or less which carry
power not in excess of 3200 watts.
