Electrics - AC Installation examples

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We've now (22/3/10) installed the new 230v / 120v AC transformers in three boats, a Bayliner 245 (07), Bayliner 2855 (02) and a Monterey 262 (99).  The installation was very similar in all with the transformer secured in the Engine compartment forward and to starboard of the engine, adjacent to the holding tank.  The floor in this area is level and typically of glass/ply construction providing a secure base into which to screw (x4) the transformer.

Cabling is from Cobra Marine, US colour coded - green (ground) / black(hot) / white (neutral) - and rated to 45 Amps, 600v and 105 degrees for Engine and Accomodation spaces.  Within the engine space all cabling is encased within corregated plastic sheathing and attached/supported at minimum 300mm centres, in these cases to the existing wiring led along the forward bulkhead from starboard to port.

Within the accomodation spaces cables are typically led though void spaces outboard of the accommodation panelling.

We found the easiest approach to leave the 120v supply intact at the 120v Panel  and use the shorepower connection end to attach to the 120v AC output from the transformer.  On the Bayliners the original cable connecting shorepower to panel is 8 AWG which is significantly oversize (presumably to cater for accidental connection to a 60A shorepower source).  We replace the 120v 30A US shorepower connection fitting with a European 230v 16A unit (Hubbell) and then introduce a new cable to connect this to the input (source) side of the 230v AC 16A dual pole circuit breaker panel (BlueSea).

For the Bayliners we found it easier to mount the 230v AC panel above the aft berth as this panel fronts the void space containing the wiring and access to the shorepower connection(s).  In the case of the Monterey it proved easiest to mount the panel in a locker side feeding into the same void as the 120v Panel.   This was largely because it would have been virtually impossible to introduce any further cabling between the void and the shorepower fitting.

These are relatively simple and straight forward installation.  By leaving the connections to the 120v AC panel intact there is no risk of upsetting other elements of the wiring.  Other than the transformer itself (where screw down connections are used), all other connections use pre-insulated crimped fittings.

Installation time is approximately four hours, though at least 30 minutes is spent working out exactly what goes where and gaining access to route cabling.

Written By: Rowland Smith

Rowland Smith is a Naval Architect and founder of Gablemarine.  His industry experience includes Lloyds Register, British Shipbuilders Hydrodynamics Ltd, Cammell Lairds, BP Shipping Ltd & Conoco.  He has a degree in Naval Architecture, a Diploma in Marketing (CIM) and an MBA (Cranfield School of Management).  He has also held Director level positions in a number of technology and engineering companies, including CEproof, which provides RCD compliance software to builders. 

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