Please Note: This Article is 9 years old. This increases the likelihood that some or all of it's content is now outdated.

Heat Resistance Connections (HRC) in electrical circuits are a known cause of fires in all types of premises.

It is widely appreciated among professionals that a poor electrical connection in any mains electrical circuit can potentially create a hot spot and eventually a fire, which has been a serious menace virtually since electricity first arrived in buildings.

Within the distribution board or consumer unit, avoidance of overloading has been controlled by fuses and standard circuit breakers. More recently has arrived protection against electrocution and shock which has seen the implementation of imbalance detection. This is achieved by Residual Current Devices (RCD) or Ground Fault Circuit Interrupters in North America (GFCI)

In some cases the above operations have been combined into one single unit which in the UK is known as a residual-current circuit breaker with overload protection RCBO.

There has to date never been a successful method of either isolating or alerting that somewhere within a circuit it is being affected by an HRC fault. Consequently it can so often just continue to worsen unabated.

All around the world this problem has remained unresolved simply because it has presented such a headache to do so. For the last eight years there has been a great deal of work going on behind the scenes to slay the dangers of this HRC dragon once and for all.

More than a decade ago David Heathcote (Now owner and director of Indumission Limited, also CEO Pro Active Vision Group Community Rail-Link Project) was an electrical installation inspector commissioned especially to research receptacles which were (or had been) affected by HRC.

Although at that time he had been in profession for thirty years, he had never truly focussed on the extent to which this problem persisted. Finally only when he was called to attend a fault which had already instigated a fire, almost killing an eight month old baby, he felt it was time for someone to bite the bullet and do something about it.

After a period of extensive preparation and preliminary design, Dave eventually teamed up with the multinational Vishay Intertechnology Inc. Over a period of many years of R&D activity, they created together (and internationally patented) a unique genus of discrete components specifically designed to overcome this dilemma within any fixed wire electrical installation. They named the successful outcome of this work ‘Thermarestor’.

The specialist components are the core element of the system with simply secondary developments designed to apply them. It is not only possible to address the HRC problem technically; David says he is also thrilled there is now a range of easy to apply non expensive products available to solve this problem. It has potential live saving consequences.

David says, these products have within them ‘pedigree’ components refined, tested and time cycled to the highest international standards of quality. “This obviously assures me we have mastered many arenas of this HRC hazard. I can honestly say the achievement is a world-class breakthrough for Britain.”

Most fire services from around the globe complain quite rightly about the many avoidable call outs they attend due to HRC. This can now be drastically reduced if this simple to apply technology is implemented.

David says “we are indebted to the support and assistance of Gloucestershire Fire Service for their assistance and support in the early years of development of this device.”

David warns that this is not the sort of device you can go along and buy from your local B&Q: you need to contact a qualified electrician capable of installing this in your system.

If you are an installer, consultant or end user, Indumission do not install these products, however they will offer training and will guide in the best way you can integrate the technology to existing systems.

For more information visit: and

Please Note: This Article is 9 years old. This increases the likelihood that some or all of it's content is now outdated.


Please enter your comment!
Please enter your name here