Definition
The maximum voltage that an insulating material can withstand without breaking down and allowing electric current to pass through it. Dielectric strength is usually expressed in volts per unit of thickness (such as volts per mil) and indicates how well a material resists becoming a conductor under electrical stress.
Plain English
It is a measure of how much electrical pressure an insulator can take before it fails and lets electricity punch through it.
Context Anchor
Seen in aircraft electrical-system, ignition-system, wiring-insulation, and component-maintenance discussions.
Derivation
From the Greek 'dia' (through) and 'electric' — a 'dielectric' is a material that an electric field passes through but current does not. 'Strength' here means resistance to failure. So a dielectric's strength is its ability to hold off current despite the field pushing across it.
Why Pilots Care
Adequate dielectric strength prevents insulation failure that could cause shorts, arcing, or loss of electrical systems in flight.
Analogy
Think of insulation like the wall of a hose. If the pressure gets too high for the wall, it can burst through. Dielectric strength is the electrical version of that limit.
Intuition Check
Dielectric strength does not mean the material is strong like metal or hard plastic. It means the material can resist electricity breaking through it.
Example Sentence 1
The ignition harness uses insulation with a high dielectric strength to contain the high voltage traveling from the magneto to the spark plugs.
Example Sentence 2
Engineers selected a material with higher dielectric strength to protect the wiring from voltage spikes during flight.