UL 60335-2-21
UL 60335-2-21 is the particular safety requirements for storage water heaters, covering electric storage tank-type water heaters, supplementing UL 60335-1.
Key Test Areas:
1. Pressure vessel integrity and hydrostatic testing
2. Thermostat accuracy and temperature limiting controls
3. Corrosion protection verification
4. Electrical heating element safety
5. Abnormal condition testing (dry-firing, over-temperature)
Project Details
This standard applies to electric storage water heaters with a rated voltage not exceeding 250 V for single-phase and 480 V for other appliances.
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