Earthing

In general, electrical safety can be compromised by either electric shock hazards (patients and staff) or by unplanned interruptions to supply (patients). The continuity of supply will be enhanced by a resilient design, usually incorporating back-up generators, UPS and IPS systems, which are dealt with separately in the relevant product categories.

Electric shock hazards can be reduced by incorporating IPS and structured equipotential bonding as part of the medical facilities infrastructure.

Electric shocks generally fall within two main categories: macro-shocks and micro-shocks, both of which can be harmful and fatal.

Macro-shocks are considered to be currents of at least 10mA flowing through the skin and the body and is perceived as a “shock”. At the lower end it may be felt as a “tingle”. At the upper end it may produce a massive jolt, which in certain circumstances, could result in death.  If a patient is unconscious or sedated, then he or she cannot inform clinical staff that a shock is being received.

Micro-shocks are the passage of a low level of current through the body, which causes no perceptible sensation. The threshold of sensation is generally considered at about the 1mA level. Although the subject cannot detect currents below this level, it does not mean that they are harmless. Currents as low as 10µA flowing through the heart may start to trigger ventricular fibrillation.

The correct and safe earthing of medical locations to the latest standards (including HTM06-01, IEE GN 7 and MEIGaN) is an area that is often not specified in enough detail or the background is not fully understood by every stakeholder in the project team.

In addition to providing practical design guidance on robust structured and separated earthing, Starkstrom can supply you with the full range of earthing products to allow you to successfully complete the installation.