Geysers, Hot Water Cylinders

RSA installs all types of electrical circuits for geysers. From domestic to commercial and to Industrial. There are several regulations to take into consideration which are listed below: Here’s a rundown of the key SANS 10142-1 requirements for wiring fixed electric water-heating appliances (geysers, hot-water cylinders) in a low-voltage installation: Dedicated circuit • Every fixed water heater must be on its own radial circuit—no shared sockets or lighting circuits. • The circuit may be single-phase (230 V) or three-phase (400 V), depending on the heater’s rating.
Conductor sizing and overcurrent protection • Calculate the heater’s full-load current: IFL = P ÷ V. • Choose a cable whose permissible continuous current rating ≥ IFL, allowing for ambient factors (see SANS 10142-1 Table 4.2). – As a rule of thumb for single-phase: • Up to ≈ 4.6 kW (20 A): use 2.5 mm² copper conductor, protected by a 20 A MCB. • Up to ≈ 5.8 kW (25 A): use 4 mm² copper conductor, protected by a 25 A MCB. • For higher-power units, size cable and breaker proportionally (e.g. 6 mm²/32 A, 10 mm²/40 A, etc.). • The overload (thermal) and short-circuit settings of the protective device must match the cable’s ratings.
Residual‐current protection • All circuits feeding fixed water heaters must be protected by a 30 mA RCD or by an RCD‐protected MCB. • This RCD may be installed in the consumer unit or as a local appliance‐protection device. Isolation and local switching • Provide a local, readily accessible isolating switch or switch‐fuse within 1 m of the heater. • The switch must have the same voltage and current rating as the circuit and an IP rating appropriate to the location (at least IP X4 if in a wet area).
Temperature‐rating and installation practice • Use cable rated at least 70 °C (e.g. PVC/U, single-core), or 90 °C if run through hot areas (e.g. near hot pipes). • Secure cables neatly; avoid running them too close to hot surfaces. • Where cables pass through walls or hot‐water cupboard floors, protect them with grommets or conduit. Earthing and bonding • The appliance CPC (circuit protective conductor) must be sized in accordance with SANS 10142-1 (usually matching the line conductor or per Table 4.7). • Ensure equipotential bonding to any nearby metallic plumbing (to prevent a voltage difference between heater casing and pipes). Voltage-drop considerations • Keep end‐to‐end voltage drop ≤ 4 % of nominal voltage under full load. • If the heater is far from the consumer unit, you may need a larger cable to stay within the 4 % limit. Compliance certificate • On completion the installation must be tested (continuity, insulation resistance, earth‐fault loop impedance, RCD trip times) and signed off on the prescribed Regulator’s Compliance Certificate