Shoddy wiring of hospital and surgery equipment is putting the safety of patients and staff at risk, according to officials.
Inspections have revealed evidence that people could be electrocuted by faulty connections or tripped by extension leads .
All NHS managements in Britain have been told to check the safety of medical electrical equipment and to increase the number of electric sockets to reduce the metres of cables and multiple plugs cluttering buildings.
Two Department of Health agencies, which are responsible for the safety of equipment and the condition of hospitals, have issued detailed warnings in recent weeks, indicating the level of concern. They are particularly worried by the way medical equipment is being powered through other, sometimes non-medical equipment, or through shared extension leads.
Safety officials found faults in "a large number of NHS properties". They reported, as examples, a patient monitor connected to a computer, and an endoscope - a tube through which doctors can view internal organs - connected to a domestic video-recorder. Several items of medical equipment on a trolley might share one extension lead, they said.
A recent audit of 19 NHS trusts found poor earthing of equipment, reversed live and neutral leads, plugs with loose internal screws and, in one case, broken casing material inside a socket which stopped the plug fitting properly.
The officials also strongly criticised the "hazardous practice of linking one mains extension to another", known as daisy-chaining.
Extensions were not being properly tested and, in any case, their use "is not considered a suitable long-term solution predicated by a shortage of appropriately designed or located socket outlets".
Sharing the supply of electricity in such a way "may create risks that may not have been taken into account in the design of the individual item of equipment".
The problem of faulty wiring had been identified previously in individual hospitals but the audit indicated just how widespread the dangers were.
Many trusts were "generally unaware" of this issue, the medicines and healthcare products regulatory agency said in its most recent advice, issued without publicity last week. "This represents a risk to both staff and patients."
Hospital managers have been recommended to identify the location and condition of all such extension leads, routinely check them, and, as part of routine maintenance or upgrading, install more sockets to eliminate the risks.
The warnings are also being sent to all GPs and NHS dentists and, via the government's national care standards commission to all private hospitals and dentists.
