Electrical power supply to ROV equipment

When wiring up the trailing lead of a piece of ROV equipment to a junction box on the ship’s electrical supply, an electrician incorrectly identified the trailing lead wires and connected the ROV equipment earth to a live phase on the 440 volt 3 phase supply. A key factor in this error was that the yellow covering on the phase wire of the trailing lead had a dark bank along it due to pigment discolouration from the outer cable sheath which led the electrician to presume it to be yellow/green earth.

On powering up, the Superintendent received an electric shock. This incident again highlights that ROV equipment and site conditions in which it is used invariably involves potentially fatal electrical supplies. The integrity of electrical wiring to such equipment can fail.

The contractor involved has proposed the following:

• ensure that continuity and earth checks are carried out after wiring or modifying any electrical equipment regardless of confidence in integrity of wiring
• those in charge of ROV equipment at site should be reminded that they are responsible for powering up such equipment and in every case it is essential that they seek and get formal assurance that continuity and earth tests had been carried out both on receipt and site of such equipment or after any modification to electrical supplies