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参考一下UL2021:$ }$ t: \; n$ O, E
15.2 Protection of wiring
4 |2 a* ~$ G d- T% t15.2.1 The wiring and connections between parts of a heater shall be protected or enclosed, except that4 O: z' y2 f- D2 ?1 a
a length of flexible cord may be employed for external connections, or for internal connections that may
% t) p1 W, W" K" `* o2 Sbe exposed during servicing, if flexibility of the wiring is essential.2 e2 B! y" J6 F+ b0 X2 n! K/ l
15.2.2 The internal wiring of a heater in the vicinity of a lampholder that accepts either an infrared lamp
9 J8 w$ t b5 m' vor an ordinary lamp:0 p+ ~" p5 w) O; R+ V& S
a) Shall be a jacketed type at least equivalent to Type SP-2 flexible cord. Asbestos-insulated
, |' F* d) g$ F$ bwiring and appliance wiring material is not acceptable unless provided with sleeving or tubing.
2 S8 A5 v& J- s& j" lb) Shall be routed along the metal surface of the heater enclosure and shall be so secured as4 e9 [1 ^) k7 P4 |1 z$ D7 l
to minimize the likelihood of its being hooked or grasped./ ~/ i6 u- x0 P L$ t
15.2.3 A conductor utilizing beads for insulation shall not be used outside an enclosure.7 s; `1 f! h& {
15.2.4 Internal wiring that is exposed through an opening in the enclosure of a heater is considered to be
! d* K& O5 L9 tprotected as required in 15.2.1 – 15.2.3 if, when judged as though it were film-coated wire, the wiring2 y4 i* ^- a' y+ U& x
would be acceptable according to 7.17– 7.20. Internal wiring within an enclosure is acceptable if, even, ~3 M0 B! ^" k& C
though it can be touched with the probe, it is so protected or guarded that it cannot be grasped or hooked7 W: k3 W! [2 c3 q2 @
in such a manner that it could be subjected to stress. |
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