The Uniform Plumbing Code has required seismic safety straps to be in place for most water heaters since 1982. The goal for doing so is to protect against fire, explosion of the unit, or water damage which could occur if the water heater should fall over due to an earthquake.
Initially, the code said that water heaters need to be anchored down or strapped so as to be able to withstand displacement which could be caused by an earthquake. Even so, there were no actually installation standards incorporated with this code. The type of hardware used to meet the code, and procedures for attachment were left completely up to the individual completing the installation.
During the 90's, the requirements for strapping were enhanced. The updated version of the code required that strapping be in position at points within the range of the top and bottom one-third of the unit. Since that time, no further additions or changes have been made to this code, so this is where we stand today. A pair of straps are necessary, but in regard to other specifications, specific materials, or installation techniques, there is no information.
On the other hand, the plumbing code, as it pertains to strapping for water heaters, has been replaced by higher standards put in place by the California Health and Safety Code. In 1989 the California State Legislature set up the subsequent health and safety standards:
- Every water heater sold in the state of California must be braced.
- Producers of water heaters must offer clear instructions for installation, with seismic straps to be included with each unit sold.
- The state architect must put together general installation instructions which include basic details showing the minimum standards for the application of earthquake strapping.
These specifications were posted in 1992, and continue to act as the legal requirements for acceptable strapping for water heaters installed within the state of California.
The general standards include:
- Every water heater, gas or electric, has to be strapped.
- Dual straps are required, with one being placed on the upper third of the unit, and the second along the bottom one-third of the unit. Also, the bottom strap must be 4" above the control unit.
- The strap material may either be plumbing tape (24 gauge minimum) or 1/2" metal conduit.
- Both straps must go completely around the body of the unit. (Note that a good number of the strap kits sold commercially do not meet this requirement).
- Each strap must be properly secured to the surrounding walls and from opposite directions.
- Each strap must be anchored to wall studs making use of lag bolts which are 1/4" in diameter and 3" in length.
An illustrated version of these standards can be obtained by contacting the State and Consumers Services Agency at (916) 653-3817. Simply request a copy of the information related to earthquake bracing for residential use water heaters.