Most appliance failures in Egypt are caused by low voltage, not spikes. When mains voltage sags, motors in fridges, air conditioners and pumps draw more current to deliver the same power. That extra current overheats the windings until they fail. A voltage protector disconnects the circuit before the damage accumulates.
The problem is sustained sag, not the dramatic spike
Most people picture a lightning-style surge when they think about electrical damage. In practice, the expensive failures in Egyptian homes and shops come from the opposite direction: voltage sitting below nominal for minutes or hours at a time, typically during peak summer demand.
Here is the mechanism. An induction motor draws whatever current it needs to produce its rated torque. If the supply voltage falls, the motor compensates by drawing more current. More current through the same winding means more heat. Insulation on the winding is rated for a temperature; exceed it repeatedly and it breaks down.
The result is a compressor that dies after eighteen months instead of ten years — and the failure looks like a normal breakdown, so the real cause is rarely identified.
What a voltage protector does
A voltage protector monitors the supply continuously. When voltage leaves a set range in either direction, it disconnects the circuit. When the supply returns to normal and stays there for a set delay, it reconnects automatically.
Typical settings for a 220V nominal supply are around 170V lower limit and 270V upper limit, both adjustable on the better units.
The reconnection delay matters more than people realise
Compressors must not restart against residual head pressure. Restarting immediately after a cut can stall the motor and draw locked-rotor current. A reconnection delay of one to three minutes lets pressures equalise, and it is the single setting most worth checking before you buy.
Protector, stabiliser or UPS?
- Voltage protector — disconnects when the supply is out of range. It does not correct voltage. Inexpensive, fits on DIN rail at the board, protects everything downstream.
- Stabiliser (AVR) — actively corrects voltage back toward nominal, so the appliance keeps running. More expensive, usually sized per appliance.
- UPS — provides battery backup through a complete outage. Necessary for computers and tills, unnecessary for a fridge.
For whole-property protection against Egyptian supply conditions, a DIN-rail protector at the distribution board gives the most protection per pound spent. A stabiliser makes sense where continuity matters — a shop that cannot stop trading — and the two are often used together.
Where to fit it
The usual position is immediately after the main incomer, protecting every circuit downstream. On larger properties, protectors are sometimes fitted per circuit so that a sag disconnects the air conditioning while leaving lighting on.
Rated current must exceed the load it covers. 63A and 80A units cover most domestic and light commercial boards. Dual-display models show live voltage and current, which makes diagnosing a supply complaint far easier — a logged reading is evidence.
See Over & Under Voltage Protectors and Current & Voltage Meters.
Frequently asked questions
Is low voltage really worse than high voltage?
For motor-driven appliances, sustained low voltage causes more cumulative damage because it is common and goes unnoticed. High voltage is more dramatic but far less frequent.
Will a protector stop my appliance turning off?
No — a protector disconnects deliberately to prevent damage. If you need the appliance to keep running through a sag, you need a stabiliser.
What voltage range should I set?
Around 170V to 270V suits most Egyptian domestic supplies. If the protector trips constantly, log the actual voltage before widening the range — the supply itself may be the problem.
Do I need one per appliance?
No. A single DIN-rail unit at the board protects everything downstream, which is cheaper and more reliable than individual units.