234.263—Relays.
(a)
Except as stated in paragraph (b) of this section, each relay that affects the proper functioning of a crossing warning system shall be tested at least once every four years.
(b)
(1)
Alternating current vane type relays, direct current polar type relays, and relays with soft iron magnetic structure shall be tested at least once every two years.
(c)
Testing of relays requiring testing on four year intervals shall be completed in accordance with the following schedule:
(d)
Testing of relays requiring testing on two year intervals shall be completed by the end of calendar year 1996.