Know where all the electrical switches and circuit breakers for pool equipment and lights are located and how to turn them off in an emergency.

Refrain from swimming before, during, or after thunderstorms.

Have an electrician who is qualified in pool and spa repairs inspect and upgrade your pool, spa or hot tub in accordance with applicable local codes and the National Electrical Code (NEC).

Ensure that all electrical wires and junction boxes are at least five feet away from water, as required by the NEC.

Protect swimmers from injury by following the NEC requirements for installing GFCIs:

on underwater lighting circuits operating at 120-volts (CPSC recommends GFCIs for circuits that are 15 volts or greater);
on pumps and electrical equipment used with pools, spas and hot tubs, including heaters close to the pool and operated on 240 volt circuits;
on electrical circuits around pools, spas, and hot tubs;
on all outdoor receptacles and receptacles within 20 feet of the water's edge to protect people from injury.

Test GFCIs monthly to assure continued protection. Infrequently used and portable or cord-connected GFCIs should be tested before each day's use. To test a GFCI:

Plug a nightlight into the outlet and turn the nightlight on.
Press the "TEST" button. Did the light go out? If not, replace the GFCI or have it inspected by an electrician.
Press the "RESET" button. Did the light come back on? If not, replace the GFCI.
Wear shoes while conducting the test, especially if outdoors or standing on wet ground.

Use battery-operated appliances instead of cord-connected appliances in and around a pool, spa, or hot tub.

Post an emergency plan within clear view of those using the pool.

Ensure that overhead power lines and junction boxes are safely positioned when installing a new pool, hot tub or spa.

Source: Consumer Product Safety Commission