509.4.1.1 Type IV-B and IV-C construction. Where Table 509 specifies a fire-resistance-rated separation, mass timber elements serving as fire barriers or a horizontal assembly in Type IV-B or IV-C construction shall be separated from the interior of the incidental use with an approved thermal barrier consisting of a minimum of 1/2 inch (12.7 mm) gypsum board or a material that is tested in accordance with and meets the acceptance criteria of both the Temperature Transmission Fire Test and the Integrity Fire Test of NFPA 275.
Table 509
Incidental Uses
Room or Area | Separation and/or Protection |
Dry type transformers over 112.5 kVA and required to be in a fire resistant room per NEC (NFPA 70) Section 450.21 (B)1 | 1 hour or provide automatic sprinkler system |
1 | Dry type transformers rated over 35,000 volts and oil-insulated transformers shall be installed in a transformer vault complying with NFPA 70. |
(Remainder of table unchanged)
[Statutory Authority: RCW
19.27.031 and
19.27.074. WSR 19-02-038, § 51-50-0509, filed 12/26/18, effective 7/1/19. Statutory Authority: RCW
19.27.031 and chapters
19.27 and
34.05 RCW. WSR 13-04-067, § 51-50-0509, filed 2/1/13, effective 7/1/13. Statutory Authority: RCW
19.27.031 and
19.27.074. WSR 10-03-097, § 51-50-0509, filed 1/20/10, effective 7/1/10. Statutory Authority: RCW
19.27.074,
19.27.020, and chapters
70.92, 19.27, and
34.05 RCW. WSR 07-01-091, § 51-50-0509, filed 12/19/06, effective 7/1/07.]