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参考一下UL2021:1 P* t% l! T, I$ F& ]' b# h6 Z6 H8 e7 c
15.2 Protection of wiring
6 [. `% E9 b! T7 F; {' ~6 \0 y15.2.1 The wiring and connections between parts of a heater shall be protected or enclosed, except that' j- U: Q$ s5 Z, G8 k
a length of flexible cord may be employed for external connections, or for internal connections that may1 D/ O9 z6 e: ^% a. Q# J% S4 [) r, y
be exposed during servicing, if flexibility of the wiring is essential.9 ]( S+ s6 J" ?9 N2 A9 L2 V* k
15.2.2 The internal wiring of a heater in the vicinity of a lampholder that accepts either an infrared lamp- V' p- ]5 m" E [1 j
or an ordinary lamp:
- F1 Z# L, {. N& f, t+ _$ p2 r: _5 ra) Shall be a jacketed type at least equivalent to Type SP-2 flexible cord. Asbestos-insulated
$ h" O0 w% s1 q& R" j) G) Uwiring and appliance wiring material is not acceptable unless provided with sleeving or tubing.
# l# g% C- g" e! m M7 Bb) Shall be routed along the metal surface of the heater enclosure and shall be so secured as1 [& n- u7 Z" t9 n
to minimize the likelihood of its being hooked or grasped.
3 h7 I& V7 q7 [+ f( \15.2.3 A conductor utilizing beads for insulation shall not be used outside an enclosure.
4 @- v# O' B& C( U# u S6 M/ z* A. n15.2.4 Internal wiring that is exposed through an opening in the enclosure of a heater is considered to be! }. u3 x9 T" ~7 N
protected as required in 15.2.1 – 15.2.3 if, when judged as though it were film-coated wire, the wiring
0 o0 F" ], _7 t8 U( U: Nwould be acceptable according to 7.17– 7.20. Internal wiring within an enclosure is acceptable if, even
7 G5 m# C2 [# s. y( h7 N& hthough it can be touched with the probe, it is so protected or guarded that it cannot be grasped or hooked
! Q: c' [, B1 Oin such a manner that it could be subjected to stress. |
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