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参考一下UL2021:
( T: z) N8 p' I i$ Y$ o- A15.2 Protection of wiring
, m- F3 h/ m' _1 Z* U3 U% d15.2.1 The wiring and connections between parts of a heater shall be protected or enclosed, except that
9 h% u5 D, D$ Z' E1 |, [a length of flexible cord may be employed for external connections, or for internal connections that may
5 y! c! q2 x, m. w: O3 V/ obe exposed during servicing, if flexibility of the wiring is essential.5 d; `. H; R! _* m- u$ ^
15.2.2 The internal wiring of a heater in the vicinity of a lampholder that accepts either an infrared lamp: T& t, [) w G% d6 _
or an ordinary lamp:
4 U; V/ B f( X7 E3 xa) Shall be a jacketed type at least equivalent to Type SP-2 flexible cord. Asbestos-insulated2 T0 W) \ _# N O
wiring and appliance wiring material is not acceptable unless provided with sleeving or tubing.
R: c1 z( ~0 q1 n7 Ib) Shall be routed along the metal surface of the heater enclosure and shall be so secured as
: g* g0 C0 w6 A% pto minimize the likelihood of its being hooked or grasped./ f6 K% c6 e# I% |2 Y
15.2.3 A conductor utilizing beads for insulation shall not be used outside an enclosure.4 `+ V0 Z" Q- b
15.2.4 Internal wiring that is exposed through an opening in the enclosure of a heater is considered to be
; X( F" X1 W; S8 a1 bprotected as required in 15.2.1 – 15.2.3 if, when judged as though it were film-coated wire, the wiring7 S& ?. Z6 p' O0 _& `3 q _
would be acceptable according to 7.17– 7.20. Internal wiring within an enclosure is acceptable if, even
: g: U- D5 d& T5 Rthough it can be touched with the probe, it is so protected or guarded that it cannot be grasped or hooked/ i) L4 _+ T% s
in such a manner that it could be subjected to stress. |
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