Pennsylvania Code › Title 34 - LABOR AND INDUSTRY › Part I - Department of Labor and Industry › Chapter 39 - SAFETY STANDARDS-GENERAL › Subchapter B - ELECTRIC SAFETY › SWITCHBOARDS › Section 39.177 - Guarding live parts

Current through Register Vol. 54, No. 28, July 13, 2024
(a)
Enclosure.
Switchboards operating at over 300 volts to ground
					 and located near passageways shall be guarded from these by suitable inclosures
					 or barriers and shall be made inaccessible to other than authorized persons,
					 unless under constant attendance during operation.
(b)
Mats.
For the protection
					 of the operator, if parts over 300 volts to ground are not otherwise guarded or
					 isolated by elevation, suitable insulating floors, mats, or platforms providing
					 good footing shall be so placed that the operator does not readily touch the
					 live parts, unless standing on such floors, mats, or platforms.
(c)
Parts over 750 volts on face of
					 board.
No switchboard shall have exposed on its face within six feet
					 from floor line any current-carrying part over 750 volts, except as noted in
					 subsection (e) and except direct current railway boards up to 1,500 volts,
					 which, if above nominal 750 volts, shall be so constructed that the operator
					 does not inadvertently come in contact with parts having a hazardous difference
					 of potential. Dead face panels and remote control should be utilized to achieve
					 this result if isolation by elevation is impracticable or
					 undesirable.
(d)
Exposed
					 live parts on face or back.
When working space adjacent to live parts
					 are not provided in accordance with §
											39.104 (relating to working space
					 about electrical equipment), suitable guards shall be arranged to protect the
					 operator from accidental contact with parts over 750 volts. Suitable insulating
					 guardrails, sufficiently spaced from the face or back of the board, or suitable
					 guards perpendicular to the face or the back of the board, and extending out
					 beyond the live parts should be used, if practicable.
(e)
Plug-type switchboard.
Plug-type switchboards shall, except while connections are being changed, have
					 no current-carrying part exposed on face of boards and, if practicable, they
					 and their plug connectors shall be so arranged where the operating voltage
					 exceeds 150 as to have current-carrying parts guarded so long as they are
					 alive, even while connections are being changed.
(f)
Instruments.
Metal cases
					 of instruments, unless isolated by elevation, operating at over 750 volts
					 should be grounded or enclosed in suitable covers of insulating material or of
					 grounded metal.
(g)
Exposed
					 parts over 7,500 volts.
No switchboard shall have current-carrying
					 parts above 7,500 volts exposed unguarded unless these parts are effectively
					 isolated by elevation, except at times when occasionally left exposed by
					 removal of covers or entrance into enclosures, such as switch and instrument
					 transformer cells or compartments, which are ordinarily unoccupied by persons.
					 For such parts, if exposed while alive for any purpose, including busses and
					 disconnectors in compartments, working space shall be provided complying with
					 the requirements under §
											39.160(d)
					 (relating to guarding live parts of switches and automatic cut-outs not
					 installed on switchboards).
This section cited in 34 Pa. Code §
													39.171 (relating to accessibility
						  and convenient attendance).