Draper Expert 6-48V Digital Circuit Tester

Guesswork has no place in electrical fault finding. The Draper Expert Digital Circuit Tester (CTD1) gives you a precise voltage reading on a bright LCD display the moment you touch probe to circuit — so you know instantly whether a circuit is live, what voltage it's carrying, and whether your polarity is correct.

Unlike basic test lights that only tell you a circuit is live, this digital tester shows you the actual voltage reading from 4V to 48V, making it suitable for a far wider range of diagnostic tasks across a broad spectrum of vehicle types and electrical systems.

Clear Readings. Every Time.

The centrepiece of the CTD1 is its LCD digital display, which delivers an accurate voltage readout at a glance — no squinting at a dim bulb or interpreting needle deflections. Dual LED indicators back this up with instant colour-coded feedback: red for positive and green for negative, so you can confirm polarity without taking your eyes off the probe.

Built for Reach and Precision

A generous 3.6m (approximately 12ft) cable with an insulated crocodile clip earth connection gives you the freedom to reach circuits throughout the vehicle without awkward repositioning. The 90mm insulated and sharpened probe is designed to access hard-to-reach circuits, connectors and switches — even in tightly packed engine bays or behind dashboard panels — safely and with precision.

Unrivalled Versatility

One of the standout qualities of the Draper CTD1 is its compatibility across a wide voltage range and vehicle types. Whether you're tracing a wiring fault on a 6V classic car, checking a 12V motorcycle circuit, diagnosing a 24V commercial truck system or testing a 48V mild hybrid vehicle, this single tool covers it all. It's equally well suited to marine, trailer and agricultural applications, making it a true go-anywhere diagnostic tool for the professional workshop or serious enthusiast.

Key Features & Benefits

• LCD digital display — Clear, accurate voltage reading from 4–48V DC at a glance
• Dual LED indicators — Red for positive, green for negative; instant polarity confirmation
• Wide voltage range — Suitable for 6V, 12V, 24V and 48V DC systems
• 90mm insulated sharpened probe — Reaches inaccessible circuits, connectors and switches safely
• 3.6m (12ft) cable — Generous reach for testing across the full length of any vehicle
• Insulated crocodile clip earth — Secure, safe earthing connection
• Multi-vehicle compatibility — Cars, motorcycles, commercial vehicles, trailers, boats and agricultural machinery
• Draper Expert quality — Engineered for professional reliability and durability

Who Is It For?

The Draper Expert CTD1 is the ideal choice for professional mechanics, auto electricians, fleet engineers and serious DIY enthusiasts who need a reliable, multi-voltage circuit tester for a variety of vehicle types. Its wide voltage range and durable build make it particularly valuable in agricultural, marine and commercial vehicle settings where 24V and 48V systems are commonplace.

Technical Specifications

• Digital LCD display shows precise voltage readings from 4–48V DC
• Red and green LED indicators for instant positive/negative polarity confirmation
• Covers 6V, 12V, 24V and 48V DC systems — cars, motorcycles, vans, HGVs, boats, trailers and agricultural machinery
• 90mm insulated and sharpened probe for accessing tight or inaccessible circuits
• Long 3.6m (12ft) cable with insulated crocodile clip earth connection
• Lightweight at 171g — easy to use one-handed
• Part of the trusted Draper Expert professional tool range
• Product Code: CTD1

Q: What voltage systems is the Draper CTD1 compatible with? The CTD1 is designed for testing 6V, 12V, 24V and 48V DC systems, with a measurement range of 4–48V. It is not suitable for AC systems or voltages above 48V.

Q: Can I use this on a 48V mild hybrid vehicle? Yes. The Draper Expert CTD1 is specifically rated for 48V DC systems, making it one of the few circuit testers suitable for use on the 48V mild hybrid electrical systems found in a growing number of modern vehicles.

Q: How is this different from a basic test light? A standard test light only tells you whether a circuit is live. The Draper CTD1 goes further by displaying the actual voltage on an LCD screen, confirming polarity via colour-coded LEDs, and covering a much wider voltage range — making it a considerably more useful and accurate diagnostic tool.

Q: Is the probe safe to use in tight spaces? Yes. The 90mm probe is fully insulated and sharpened to allow safe, precise access to inaccessible circuits, terminals and switches without risk of accidental short circuits.

Q: What vehicles is it compatible with? The CTD1 is compatible with most vehicles including cars, motorcycles, commercial vehicles (including 24V HGVs), trailers, boats and agricultural machinery — essentially any vehicle with a 6V, 12V, 24V or 48V DC electrical system.