Yacht -shore power receptacles

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thakerrohit

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I have come across yacht-club having lot of receptacles but works with approximately .38 diversity factor compared to load calculated by NEC. Would NEC permit to size the conductors to be reduced based on actual site where transformer was never overloaded and that is the proof of last 10 years. Alternatively owner is ready to do datalogging to prove their load.
 
Re: Yacht -shore power receptacles

If you are looking to get an exception to the proper sizing of conductors and protective equipment as specified in the code I would say you have a better chance hitting the Powerball lottery 3 times over. :p
 
Re: Yacht -shore power receptacles

Load calculations in the NEC should've been for guidance only, similar to the voltage drop. It has nothing to do with safety, provided that adequate protection is in place. There is a big difference between the POCOs and NEC load calculations methods. Not to mention ship building etc. However, POCOs are exempt.

I think some special interests put this numbers - 3 watts/sqf lighting load, 8 KW range min ..... to boost sales on the back of the consumers.

There is no substitute for a good electrical engineering.
 
Re: Yacht -shore power receptacles

Those who write the code and those who enforce it are well aware that the actual load that you are likely to see over the life of a facility will be less than the load that is calculated per article 220 (or in your case, 555). The utilities take advantage of that fact by providing a transformer that is typically 40 ? 60% of the calculated load. But the utility is not subject to the NEC; the owner is. The NEC provides the minimum requirements for a safe installation. The owner has no option for doing less.
 
Re: Yacht -shore power receptacles

I finished a marina about 18 months ago and I installed a couple of 1,000 amp panels (as derated per the NEC) and the power company feed each with a dedicated 100 KVA transformer. No problems that I'm aware of yet.

The service conductors will need to be sized to the calculated load. If you are a PE, and you are willing to "overrule" the NEC (never met a PE yet that would do that), then you can size the conductors for less. Not sure why you would go out on that limb though. Boats are getting more electrically demanding.

Good luck.
 
Re: Yacht -shore power receptacles

There is a FPN following the derating table in 555 (I think 555.12) that tells you that the use of the derating may result in an inadequate installation in areas where it is either cold or hot! Talk about leaving you hanging! I would be very cautious about derating in a marina. The use of electricity on boats is growing rapidly. Boat owners will come up with all kinds of inventive ways to keep breakers from tripping and keep their air conditioners and other appliances running. I once saw a marina where the owner took the cover off his distribution panel and set a large fan in front of it on holiday weekends to cool the breakers and get a few more amps out of them!
 
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