How to set up for 240v?

Canal Boat - - Back Cabin: -

QI am plan­ning the electrics for a Dutch barge (sup­ported by an elec­tri­cian!) and look­ing for guid­ance. Would it be all right to wire the boat, sock­ets, lights, ap­pli­ances etc, us­ing 240v as fol­lows:

Shore power, gal­vanic iso­la­tor, in­verter charger unit (with RCD), leisure bat­ter­ies, in­verter charger then feed­ing var­i­ous ser­vices (sock­ets, in­te­rior lights, ex­te­rior lights, bilge pumps, wa­ter pump, fridge etc.) The in­verter charger unit will be con­nected to en­gine and a por­ta­ble gen­er­a­tor and so­lar pan­els. CON­ALL PLATTS, via email

ATONY REPLIES... I can give gen­eral point­ers, but not spe­cific ad­vice on mains power sys­tems on boats, your (qual­i­fied) elec­tri­cian should give you that.

A gal­vanic iso­la­tor should pre­vent any stray earth currents cor­rod­ing the hull, but I would pre­fer an iso­la­tion trans­former if the boat were to be con­nected to the shore­line for long pe­ri­ods.

There should be one sin­gle earth point be­tween the on­board 240v elec­tri­cal sys­tem and the hull, but the iso­la­tor or trans­former will iso­late this from the shore-side com­pany mains earth. You need this hull bond so the RCD will op­er­ate in the event of a fault.

The gen­er­a­tor and/or in­verter might cause com­pli­ca­tions if ei­ther use a cen­tre tapped float­ing earth, but an ex­pe­ri­enced marine qual­i­fied elec­tri­cian should know how to deal with this cor­rectly.

A com­bined charger / in­verter might not be such a good idea on two counts. Firstly, if it fails, you lose both sys­tems and se­condly, you need to en­sure that, in the event of a power cut when on shore power, the in­verter will not try to power the bat­tery charger sys­tem – oth­er­wise you will end up with very flat bat­ter­ies.

Or­di­nary twin and earth mains ca­bles (us­ing one or a few thick con­duc­tors) are likely to snap un­der vi­bra­tion and are not suit­able for boat use. Most peo­ple use arc­tic grade flex. Use boot­lace fer­rules when mak­ing screw con­nec­tions to flex.

Us­ing 240v for things such as light­ing means ex­tra bat­tery losses be­cause the in­verter will not be 100% ef­fi­cient (we usu­ally reckon on 80% for cal­cu­la­tions). Also, if the in­verter fails you will have no lights. I am not sure how easy it will be to get mains wa­ter pumps, shower drain pumps etc. I would use 12v or 24v light­ing and pumps, with mains for the rest.

You need to en­sure only one of your three AC sources (shore­line, gen­er­a­tor, in­ver­tor) is con­nected to the boat’s mains wiring at any one time, oth­er­wise the phases will prob­a­bly not be in sync (al­though some in­verter mod­els can sync them­selves) and ex­pen­sive dam­age may re­sult.

This could be as sim­ple as one mains socket for each sup­ply, with the boat’s wiring con­nected to a sin­gle plug; or there are man­ual and au­to­matic sys­tems that can se­lect one at a time.

Use a gal­vanic iso­la­tor

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.