Will Air Con trip the shore power fuse

[DavidJ]

I want to fit air con to my boat but my marina shore power trip switch in Spain is rated at 15 amp. Although the AC unit runs at 8 Amp the start up amps is 20A. Maybe the surge is too short to trip the switch? ...any practical (rather than theorectical) experience out there of running Air Con from 'normal' shore power.

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[tcm]

i think you will be ok. You shd be able to start the unit with no load, praps also with the fans on alone, then switch on the actual airco and then the remote units. Back-emf of 20A for an 8-amp unit sounds high. Obviously, knock off all heating esp water heating on startup.

Based on actual experience inthe uk, the thing will blow the shorepower, then blow the shorepower again. Then Mr nextdoor will go mental, and he'l be sloshed, you'll be reasonable but he'l be swearing and threaten to punch your face in. But then you realise he is sloshed and 15 years older so you say no mate, you won't actually duff me up, you'll be in the water. Later, you'll find that you wired the plug badly.

Based on actual experience in the med, it'll work but cost you 400 quid a montht if you have crew who run it all day every day. Or, at a visitors berth where you can have monster 60- 150 amps foc, the boat will get a bit sodding cold, like a cold meat storage unit, even in august.

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[Deleted User YDKXO]

I've run my aircon from 16 amp sockets without problem in Spain. Could be that Spanish amps are more virile than the weedy UK variety that tcm uses now
If start up load is the problem, maybe start the aircon on the genny and switch to shorepower? Probably a stupid idea

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[DavidJ]

Thanks tcm for your amazing reply.
I hadn't considered the drunken excesses of geriatric neighbours in my calculations.
I'm in the under 12m catagory so my elec in the Med generally comes for 'free' but it does also mean that I'm unlikely to be able to hook up to the giant size elec sockets.

I've just signed up for a year in Ampuriabrava so would be a bit dissapointed to fit AC and then find I can't use it.

Incidently I've checked the spec and for a 8000 BTU unit (for the cabin) the start current is 21A with a running current of 3.4A so something quite dramatic must happen on startup.

Thanks

Any more practical experiences out there?

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[DavidJ]

Thanks Mike
I think I'll call starting the AC on the genny, plan "B".
However, I'm reassured by your experience and will go ahead....Boat show with cash in hand here I come!!
David

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[jfm]

you will be fine

David, i think you'll be ok. On our old 12m berth in France we had only a 15A supply but the aircon never tripped it. The circuit breakers on the shorepower boxes are always "slow blow". When we installed our aircon on the old boat, we deliberately bort 2 compressor units in the lazerette so we could turn em on sequentially, so reduce this problem. In the end we didn't need to.

On our current boat our ammeter is a nice traditional guage with undamped needle, so the start up instantaneous currents on mortorised gear, esp aircon, flips the needle well round to 80A or summink. Yet our 30A shorepower doesn't trip out.

So, basically, I think your shorepower rating is continuous, and you are ok to exceed it massively for .25 seconds with start up of motors. In any case, shorepower is a basic copper wire system so it would be absurd, engineeringwise, to have quick blow circuit breakers. you'd always install slow blows.

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[DavidJ]

Re: you will be fine

jfm
Excellent...thanks

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