Hot Tub RCD Troubleshooting

Wiring Check Precautions (always consult an electrician as RCD wiring can vary considerably):

• When working in a system box always be aware that it may contain high voltage.
• Always keep your fingers and hand tools away from any wiring or circuit board when the power is on. Touching anything in these areas can result in serious injury.
• All repairs, no matter how minor, should include a complete wiring check, beginning with the house breaker.
• Keep in mind, that most spas only run on single-phase electrical service. Three-phase power will not supply proper voltage to the system. Three-phase power may overheat the pumps and cause the Residual Current Device (R.C.D.) to trip.

Check for Loose Connections or Damaged Wires:

• Make sure the power is off before you touch any wiring.
• Once the power is off, carefully examine all wires for cuts or defects.

RCD Associated Problems:

The spa does not run, no power, and nothing is working:

1. Check the incoming power for proper potential (voltage: 220-240v). Check breaker. Do not continue until you are satisfied that the power checks out correctly.
2. Test and reset RCD. If RCD does not stay set, disconnect all loads from the control system i.e.(pump cable, blower cable, heater cable, Ozonator cable, etc). If the RCD still does not stay set, then either the internal wiring is shorted or the RCD is faulty. If RCD remains set, reconnect each load (lead) until RCD trips again. We recommend turning off the spa in-between each lead being refitted, remember to turn each device on before proceeding to the next load device. The last load connected must be because of failure (be aware that some devices will not operate without others, i.e. heat will not engage without the pump).
3. If RCD tests and resets, check the fuse - If the fuse blows again, disconnect all loads as in step 2). If the fuse continues to blow there is an internal wiring problem. If the fuse remains good, reconnect each load one at a time until failure reoccurs as in step 2). The last unit connected before the fuse fails must be the cause.
4. If Steps 1) through 3) check positive but the unit still will not power up, check the flow-through heater manifold. (make sure the heater element is not touching the sides of the manifold. If it is, move the element away from the manifold with a long screwdriver. Make sure the power is disconnected. Inspect valves to make sure they are fully open, and inspect filter element (run unit without a filter if possible to see if symptoms change). If all previous checks show positive, replace the high limit switch.
5. If Steps 1) through 4) check positive, internal control system wiring or circuit board is at fault. Replace this unit or now it is time to get a professional in to confirm your findings.

RCD keeps tripping.

1. Firstly check the heater element (maybe corroded through, pitting, etc) - Spa Heater Troubleshooting. With the power to spa off, turn the temperature down. Then restart the pump (either speed). If the pump runs without tripping the RCD, turn the temperature up to activate the heater. If the RCD trips, then proceed to 2).
2. With power disconnected, remove both heater element power leads (and wrap exposed lugs with electrical tape to prevent the possibility of a short). If the RCD does not trip, replace the heater element/ heater.
3. If RCD trips with the element disconnected, disconnect power and disconnect all loads from the control box (pump, blower, heater, ozone, etc). Re-start. If RCD still does not stay set, internal wiring is shorted or RCD is faulty. If RCD remains set, reconnect each load until RCD trips again. The last load connected must be the cause of failure (remember that some devices will not operate without others, i.e. heat will not engage without the pump).

Notes: Does the power trip out only at the start of a filter cycle? Most controller systems have filter or purge cycles that come on by themselves once or twice a day. Most of these cycles start all the pumps, including the blower and if you have ozone that is sometimes started as well. So it is likely to be one of those components that only come on during the filter cycle, that is tripping your power out.

Most of today's spas have 12v light systems. A leaking light housing can cause the RCD to trip. Also, check for a flooded blower or Ozonator.

RCDs for the majority of UK hot tubs should be type C rather than type B, check this as a last-ditch attempt before calling the professionals.