1.10.5.5 Bending Space for Conductors. Bending space for
conductors operating at 600 volts or below shall be provided in
accordance with the requirements of 3.14.2.14. Conductors operating
over 600 volts shall be provided with bending space in accordance
with 3.14.4.2(a) and 3.14.4.2(b), as applicable. All conductors shall be
cabled, racked up, or arranged in an approved manner that provides
ready and safe access for persons to enter for installation and
maintenance.
Exception: Where 3.14.4.2(b) applies, each row or column of ducts on
one wall of the enclosure shall be calculated individually, and the
single row or column that provides the maximum distance shall be
used.
1.10.5.6 Access to Manholes.
(a) Dimensions. Rectangular access openings shall not be less than
650 mm × 550 mm. Round access openings in a manhole shall not be
less than 650 mm in diameter.
Exception: A manhole that has a fixed ladder that does not obstruct
the opening or that contains only one or more of the following shall be
permitted to reduce the minimum cover diameter to 600 mm:
(1) Optical fiber cables as covered in Article 7.70
(2) Power-limited fire alarm circuits supplied in accordance with
7.60.3.1
(3) Class 2 or Class 3 remote-control and signaling circuits, or
both, supplied in accordance with 7.25.3.1
(b) Obstructions. Manhole openings shall be free of protrusions
that could injure personnel or prevent ready egress.
(c) Location. Manhole openings for personnel shall be located
where they are not directly above electric equipment or conductors in
the enclosure. Where this is not practicable, either a protective barrier
or a fixed ladder shall be provided.
(d) Covers. Covers shall be over 45 kg (100 lb) or otherwise
designed to require the use of tools to open. They shall be designed or
restrained so they cannot fall into the manhole or protrude sufficiently
to contact electrical conductors or equipment within the manhole.
(e) Marking. Manhole covers shall have an identifying mark or logo
that prominently indicates their function, such as “electric.”
1.10.5.7 Access to Vaults and Tunnels.
(a) Location. Access openings for personnel shall be located where
they are not directly above electric equipment or conductors in the
enclosure. Other openings shall be permitted over equipment to
facilitate installation, maintenance, or replacement of equipment.
(b) Locks. In addition to compliance with the requirements of
1.10.3.5, if applicable, access openings for personnel shall be arranged
such that a person on the inside can exit when the access door is
locked from the outside, or in the case of normally locking by padlock,
the locking arrangement shall be such that the padlock can be closed
on the locking system to prevent locking from the outside.
1.10.5.8 Ventilation. Where manholes, tunnels, and vaults have
communicating openings into enclosed areas used by the public,
ventilation to open air shall be provided wherever practicable.
1.10.5.9 Guarding. Where conductors or equipment, or both, could be
contacted by objects falling or being pushed through a ventilating
grating, both conductors and live parts shall be protected in
accordance with the requirements of 1.10.2.2(a)(2) or 1.10.3.2(b)(1),
depending on the voltage.
1.10.5.10 Fixed Ladders. Fixed ladders shall be corrosion resistant.