Spark Gaps

Teledyne Reynolds UK Spark Gaps are gas-filled, high-energy switching devices designed to protect equipment and control energy discharge in high-voltage systems. They remain non-conductive during normal operation, then switch rapidly into conduction when a defined breakdown condition is reached. This makes spark gaps a proven choice for surge protection, crowbar switching, and pulsed-power discharge in demanding aerospace, defence and industrial environments.

Spark gaps are especially effective when you need a protection element that can handle very high peak currents and fast transients with minimal standby loss. They are commonly specified to mitigate high-energy events such as lightning-induced surges, switching transients and other severe overvoltage conditions. In pulse systems, they can also provide a controlled discharge path to release stored energy quickly and repeatably.

Why engineers specify spark gaps

• High surge capability for severe transient events
• Fast switching to clamp overvoltage and protect downstream electronics
• Low standby impact (normally open until breakdown)
• Robust ceramic-to-metal construction suited to harsh environments
• Repeatable breakdown behaviour when correctly selected and integrated

Typical applications

• Lightning and transient protection for high-voltage equipment
• Surge protection for power supplies and power distribution
• Pulse discharge paths in pulsed-power systems
• Protection of sensitive circuits exposed to high-energy transients
• Energy diversion and overvoltage clamping in high-reliability platforms

Selection guidance

Spark gaps are selected by matching the protection objective to the electrical stress you expect in the real system. For best results, consider both steady-state and transient behaviour.

• Operating voltage: normal working voltage plus margin (avoid nuisance firing)
• Breakdown level: low enough to protect components, high enough to avoid false switching
• Surge waveform: peak current and pulse shape (your transient standards matter)
• Repetition rate: single-event vs repetitive pulsing and expected life
• Integration: creepage/clearance, mounting, insulation coordination and lead inductance
• Environment: temperature range, vibration/shock, humidity/contamination, altitude

Related links: Spark Gaps  |  High Energy Devices category  |  Reynolds UK overview

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Frequently Asked Questions

1) What is a spark gap and what does it do?

A spark gap is a gas-filled switching device that stays “open” during normal conditions, then conducts when a defined breakdown voltage is reached. When it conducts, it provides a low-impedance path that diverts energy away from protected circuitry or creates a controlled discharge path in a pulse system.

2) When is a spark gap a better choice than an MOV or TVS device?

Spark gaps are often preferred for very high-energy surges where peak current and energy levels can exceed what solid-state suppressors can tolerate. They also offer minimal standby impact because they do not conduct until breakdown.

3) How do I choose the correct breakdown voltage?

Choose a breakdown level above your maximum normal operating voltage (to avoid nuisance firing) but below the level that could damage protected components. Include margin for tolerances and consider the actual transient waveform and source impedance, not only the steady-state voltage.

4) What information do you need to recommend a spark gap quickly?

Share your maximum working voltage, expected transient peak and waveform (or the standard you’re designing to), repetition rate, the protection topology (line-to-ground, line-to-line, etc.), environmental conditions, and any mechanical constraints such as clearance, mounting, and lead length.

5) Do spark gaps affect normal circuit operation?

Typically the impact is small because a spark gap remains non-conductive until breakdown. In sensitive circuits, you should still consider parasitic effects (such as capacitance) and ensure layout and insulation coordination are appropriate.

6) Can spark gaps be used for repetitive pulsing?

Yes, provided the device is selected for the pulse energy and repetition rate involved. Repetitive use depends on the current waveform, energy per pulse, thermal effects, and expected service life.

7) What installation details matter most for performance?

Keep connections short (to minimise inductance), maintain creepage/clearance and insulation coordination, and ensure mounting prevents contamination paths. In higher-energy circuits, consider appropriate series resistance or impedance as required by the protection design.

8) Are spark gaps suitable for aerospace and defence environments?

Yes—spark gaps are widely used in high-reliability platforms where severe transients and harsh environments are expected. Suitability for a specific programme depends on your qualification and documentation requirements and the operating envelope of the application. ​