case studies


Case Study 1.

Two commercial carrying vessels, custom designed and built for the transport of
aggregates. Although less than three years old, a complete rewire was ordered on
grounds of safety and operational efficency, to take place along with other repair
work that had been scheduled.
Boats operate daily Mon-Fri so refit work was required to fit in with a lock closure
in the winter, the time schedule for both boats being two weeks.
The tight timescale and lack of daylight was further complicated by there being no
onsite power during the first week, apart from what I was able to supply from my
onboard inverter.
Working conditions were cold, damp, dirty and dangerous- a reminder of how things
must have been in the old days of canal freight traffic.

The Problems

There was very little positive that could be said about the existing installation.
The client had little faith in the system following numerous functional failures
and potential fire risks. It was also required to upgrade the system's safety functions
to include engine warning devices, and reliable bilge warning and pumping systems.

Main DC Circuits

The boat's DC systems are 24V supplied by two starter type batteries in series. Items
requiring attention included:

-isolator switch 6 metres away from batteries, main cabling not sheathed or protected (pic)
-no suitable termination block for negative returns (pic)
-no fuses in main circuits
-inverter cables insufficent for amp draw (pic)

DC Power Distribution

-circuits used a pair of 6 way fused switch panels of poor quality (pic). Some circuits had failed due to broken fuseholders and switches and the supply to the panels was inadequate.(pic)
-negative returns terminated on a polythene terminal block hanging in mid air (pic).
-items of equipment were unsupported and hung by their connecting wires, such as this
DC-DC converter (pic).
-the boat steelwork was used as a conductor, negative returns connected to various bolts (pic).
-it was not possible to open the instrument panel for inspection without accidentally
disconnecting cables (pic).
-outdoor circuits were inadequately protected against inpact and the effects of weather

AC Power

-only one single socket was fitted
-there was no RCD for shock protction
-the ground terminal was not bonded to the boat steelwork
-the system was not polarised (neutral floating)