Meditest Ltd.

Expert and professional service always!

Black Museum

To complement our White Papers we have our Black Museum. This section contains examples of some of the damaged and faulty equipment we have come across in the course of our work.  If you have anything similar in your practice DO NOT USE IT!  These items are all dangerous and are one of the reasons why electrical safety testing is needed.

You also need to be aware that not all dangers are visible (just like many illnesses and diseases cannot be seen externally), which is why we perform a range of diagnostic measurements to locate hidden problems.


Three pin plugs are a common source of problems.  This one was broken because a desk had been pushed against it with force.  When it was found it was still plugged in and being used.

Some plugs are not well made.  This is a two piece plug held together with glue (made that way on the factory rather than a repair).  The top has come off exposing live terminals.

This is an example of a rewireable plug being incorrectly fitted. The phase (brown) conductor has been placed across the barrier that is meant to separate the earth conductor, and in the process the insulation has been cut through and eventually has short circuited to the earth conductor.  This had the potential to put mains voltage on the case of the equipment but fortunately tripped the breaker before more harm was done.

There are good repairs and there are bad repairs.  Guess what sort this is.

This is another example of a poor repair.  Sticking plaster may be good for mending bodies but it is not made for electrical equipment.  Even so, electrical tape would not be a suitable repair either.

The cord grips on these plugs are notorious for giving way. So much so that we usually replace them as a matter of course. They are not an old design, but there are still plenty around.

There is a reason why standardisation of colour coding is important. This device as supplied has a red earth wire.  Guess which terminal it will be connected to if a new plug is fitted one day?


When cords have been flexed many times, sometimes they just can't take any more. We try to locate this sort of wear and tear before it becomes a problem.

These cables were caught up in the workings of a motorised bed. The (double insulated) metal bed frame is unearthed and could easily become live. This problem is relatively common and often ignored by operators.

Another case of a damaged cord, this time from an examination lamp. In the lower section somebody has attempted a repair with electrical tape.

First aid with medical tape once again!

The cord on this ECG is a good example of failure from repeated flexing. This could have resulted in burns to the operator or even a fire.

There are actually three problems here. the button has come off the lamp switch leaving live contacts exposed below, the plastic cord grommet has come out, and the cord has been badly chafed. This lamp is potentially repairable, but we would probably recommend a replacement.

This problem is not what you might at first think. The switch has not fallen out, though they sometimes do. The problem is actually that the switch has been fitted in the (blue) neutral wire instead of the (brown) phase. This was a new lamp and was wired incorrectly in the factory.

Sometimes well intentioned people attempt their own repairs and modifications. The nebuliser has had an on/off switch fitted. the contacts you see are uncovered and accessible to the operator. This is clearly unsafe. In New Zealand it is illegal for unlicensed persons to undertake electrical work and people are regularly prosecuted for this.

There are dangers in using adaptors with foreign plugs.  In this case the exposed pin you see is live with mains voltage (or it would be if we had not made sure the switch was turned off).

A safe adaptor will have a flange or other design feature to prevent this happening, however we do not recommend the use of adaptors at all unless there is no alternative. It is better to either replace the plug, or purchase a new power pack that meets New Zealand standards.

Another case of a dangerous adaptor on a foreign plug. In this case the earth pin is not connected.

This connector is designed as a low voltage microphone connector, but a particular brand of surgical diathermy uses it as a connector for the foot switch. The male pins in the receptacle (at top) are live at mains voltage when the foot switch is disconnected. Most unsafe yet they were manufactured like this (in the 1960s).

Do you have one of these?  If you do then don't use it!  These Birtcher Hyfrecators were manufactured from the 1940s with little thought to modern standards of leakage currents and patient safety.  Even when new they probably delivered a small amount for mains voltage through the hand-piece electrode to the patient. Many years later degraded dielectrics and insulation are a certainty and one of these could well be a death trap.  While they may have been good in their day, their only place today is in a museum.