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参考一下UL2021:
6 n/ i/ i# v* `15.2 Protection of wiring
/ B+ L, q6 T* c: p, Y15.2.1 The wiring and connections between parts of a heater shall be protected or enclosed, except that
( c# G0 W4 }0 `, i, o ~a length of flexible cord may be employed for external connections, or for internal connections that may
2 a6 w! Z& H& N1 |& Z- Jbe exposed during servicing, if flexibility of the wiring is essential.- m, x% _! [6 G. h5 A0 g2 `* J
15.2.2 The internal wiring of a heater in the vicinity of a lampholder that accepts either an infrared lamp
9 i8 i) q! f6 {/ X4 z: g$ aor an ordinary lamp:
& `6 [) G. c. i8 J& S+ l aa) Shall be a jacketed type at least equivalent to Type SP-2 flexible cord. Asbestos-insulated
" D% u/ g* d$ e- m* t' J) Z2 l1 lwiring and appliance wiring material is not acceptable unless provided with sleeving or tubing.& O4 b/ c0 ?0 X* }% ^ ^5 b
b) Shall be routed along the metal surface of the heater enclosure and shall be so secured as
- y7 K6 W' c$ @: B1 ?to minimize the likelihood of its being hooked or grasped.
1 O9 X) `5 @! o h( Q* u15.2.3 A conductor utilizing beads for insulation shall not be used outside an enclosure.
! i9 a# Z9 A7 a( H# x8 h9 f! g- g* D3 v15.2.4 Internal wiring that is exposed through an opening in the enclosure of a heater is considered to be
4 w4 x# H& f! dprotected as required in 15.2.1 – 15.2.3 if, when judged as though it were film-coated wire, the wiring
9 y4 n& S. |& \5 m; m" l5 B. Jwould be acceptable according to 7.17– 7.20. Internal wiring within an enclosure is acceptable if, even' \, Q. ~7 p Q8 I
though it can be touched with the probe, it is so protected or guarded that it cannot be grasped or hooked
) M* d1 j' ` _in such a manner that it could be subjected to stress. |
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