An incident has been reported where a probe contact spring was found to be missing from a Drummond MTL15 test lamp manufactured by Martindale Electric.

This missing spring resulted in intermittent contact between the test probe and the LED circuit. When proven with a 690V proving unit the indicator illuminated, but when in contact with 230V mains it did not, leading to a “near miss”.

Many thousands of these products have been sold and this is the only such incident that has been reported. All stocks at Martindale Electric of MTL15 and MTL10/20 (which share similar housings) have been checked and no further instances have been identified.

We conclude that this is an isolated incident where either the spring was lost in service or was not fitted at the point of manufacture. The spring ensures reliable contact under varying degrees of pressure and probe angle when in use. The spring fits firmly in the contact assembly and is designed to remain securely in place.

As part of the standard procedure to ‘’inspect the unit and accessories for damage’’, we recommend users carry out the following checks:

1. Before first use check the springs are in place as shown below
2. After removing probes to swap probe lengths check the spring is in place
3. When inserting alternative probes be aware that there should be a tactile response as the spring is compressed

Spring present in probe


Spring missing DO NOT USE


Martindale is issuing this advisory notice as a precaution because of the tremendous importance we put on customer safety and product reputation. The MTL15 as well as the MTL10 and MTL20 remain safe to use, subject to routine user inspection.

All voltage indicators and test lamps should be proved before and after use in accordance with safe isolation procedures. It’s good practice to always match the maximum output voltage of the proving unit with the maximum voltage range of the test lamp. The recommended proving devices for Drummond MTL test lamps are the Martindale PD440 for MTL10/20 and PD690 for MTL15.

If you require further advice or assistance, please contact Martindale Technical Support on 01923 441717 or email