Cruisers Forum
 


Join CruisersForum Today

Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 21-10-2019, 07:25   #46
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Helsinki (Summer); Cruising the Baltic Sea this year!
Boat: Cutter-Rigged Moody 54
Posts: 25,638
Re: Shore Power Connections -- Again

Quote:
Originally Posted by GordMay View Post
WRONG!

There are, at least 4 applicable rules, in the National Electrical Code.

NEC Sections 210-22(c), 220-3(a), 220-10(b), and 384-16(c) all relate to the sizing rules for overcurrent protective devices (OCPDs).
The first three all specify the same requirement:
OCPD size = 100% of noncontinuous load + 125% of continuous load.
Sec. 384-16(c) has the same requirement, except that it's stated in terms of the loading of the OCPD. This rule states that an OCPD can be loaded to only 80% of its rating for continuous loads. Remember that 80% is the inverse of 125% (0.80 = 1 [divided by] 1.25) and, as such, the rules are indeed identical in their end requirement.


I see Dockhead beat me to it - with a fifth rule.



I learned something really important here! :lightbulb:


I have been known to overdrive a 16 amp shore power connection by a couple of amps, then use it continuously. Now I know that this is bad, bad, bad


From now on, I know better, and understand that all circuit ratings are NOT indeed for continuous use. A 16 amp circuit should not be used continuously at more than 13 amps, or only 3kW. Who knew? Man, I have more than 3kW of loads going in my boat all the time, especially in winter when I'm running electric heat, heating water, etc.



Maybe I should have dual inlets and hook up to two 16 amp outlets, when I'm running electric heat. I could get away with that from the shore power inlet to my panel, because all that including the SmartPlug is designed and rated at 32 amps, so good for 26 amps of continuous load, or about 6kW.
__________________

__________________
"Parce que je suis heureux en mer, et peut-ętre pour sauver mon ame. . . "
Dockhead is online now   Reply With Quote
Old 21-10-2019, 07:26   #47
Marine Service Provider

Join Date: Sep 2008
Location: Victoria B.C.
Boat: CS27
Posts: 2,052
Re: Shore Power Connections -- Again

Quote:
Originally Posted by Dockhead View Post
Sorry, but this is not true. I wasn't aware of it myself, but the 80% Rule most definitely exists:


Article 210.19(A)(1)
"General. Branch-circuit conductors shall have an ampacity not less
than the maximum load to be served. Where a branch circuit supplies
continuous loads or any combination of continuous and noncontinuous
loads, the minimum branch-circuit conductor size, before the
application of any adjustment or correction factors, shall have an
allowable ampacity not less than the noncontinuous load plus 125
percent of the continuous load
."


2014 National Electrical Code.

What this means is that the nominal capacity of a circuit is not indeed the real capacity for CONTINUOUS loads. It means that according to the design parameters of the National Electric Code, the conductors of a circuit rated at x amps are suitable for continuous loads of only 80% of that.



All news to me, but it is real!


See: https://www.electricallicenserenewal...sectionID=26.0
It is also stated in Marinco's documentation. 30 amp cord is rated for 24 amps continuous and 30 for 3 hours.
__________________

mitiempo is offline   Reply With Quote
Old 21-10-2019, 07:40   #48
Senior Cruiser
 
GordMay's Avatar

Cruisers Forum Supporter

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 36,327
Images: 241
Re: Shore Power Connections -- Again

LOAD CALCULATIONS:
Article 220 of the National Electrical Code lays out the primary requirements for performing load calculations, that are necessary for determining the size of a residential service. The calculations are based on the expected loads present in a dwelling unit, along with appropriate demand factors that are used to account for the diversity of electrical use by occupants.
Although most of the actual load calculation requirements are in Art. 220, others are scattered throughout the Code, and still come into play when making certain calculations, including:
Branch circuits — Art. 210
Areas supplied by small appliance circuits — 210.52(B)(1)
Feeders — Art. 215
Services — Art. 230
Overcurrent protection — Art. 240
Wiring methods — Art. 300
Conductors — Art. 310
Appliances — Art. 422
Electric space-heating equipment — Art. 424
Motors — Art. 430
Air-conditioning equipment — Art. 440
NFPA 70: National Electrical Code (NEC) Section 220https://site.ieee.org/icps-ehe/files...rticle-220.pdf
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 21-10-2019, 07:51   #49
Marine Service Provider

Join Date: Jan 2012
Location: Lake Ontario
Boat: Douglas 32 Mk II
Posts: 2,901
Re: Shore Power Connections -- Again

Shore power connections are tricky.

The biggest problem?

The majority of boaters are too ignorant, lazy, or frugal for their own good.

The standard 30 Amp @ 120Vac shore power cord and connection is perhaps not the greatest design ever conceived, but in my experience, it isn’t the design that is the problem.

If the cord and connection are maintained properly, there should be no issue.

I get asked all the time, “What is the best way to make my shore power cord look new again?”

My answer is always the same, “Replace it!”

Far more important than how good your shore power cable looks, is how good it connects.

Pay attention to your cord when connecting it to the power post and vessel.

They have a twist lock.

When you twist it, you should feel the twist lock engage. The connector should sock up snuggly to the socket.

SCREW THE RING ON!

Make sure there is strain relief on the plugs at both ends.

Walk through any marina and you will see several instances where every boat movement is transmitted to the shore power connection.

There should be a loop of cable at each end, such that when the boat moves in her slip, there is absolutely no movement in the cable at either connection.

How long a shore power cord should last, depends how frequently and carefully it is used, (or abused).

For a marina slipped boat, that is frequently used, and proper strain relief on connections not exercised, the cable connectors may be wearing and loosening after only a year or two.

I see lots of 30A shore power cords, only 3 years old that should be scrapped.

Boater: “But those things are a hundred bucks to replace!”

Ramblinrod: How much will it cost to replace your boat, a couple boats each side of you, and this section of marina dock from here to there?”

The “Smart Plug”, certainly appears to be a better 30A @ 120 Vac shore power cable/socket design.

But they are not cheap.

My fear is that the average boater will not replace these until they are way, way, way overdue.

So what the marine retailer sees, is one Smart Cable sold for at least every 100 standard shore power cable sets sold.

Why?

Ignorance, laziness, frugality.
__________________
ramblinrod
ramblinrod is online now   Reply With Quote
Old 21-10-2019, 08:03   #50
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Helsinki (Summer); Cruising the Baltic Sea this year!
Boat: Cutter-Rigged Moody 54
Posts: 25,638
Re: Shore Power Connections -- Again

Quote:
Originally Posted by ramblinrod View Post
Shore power connections are tricky.

The biggest problem?

The majority of boaters are too ignorant, lazy, or frugal for their own good.

The standard 30 Amp @ 120Vac shore power cord and connection is perhaps not the greatest design ever conceived, but in my experience, it isn’t the design that is the problem.

If the cord and connection are maintained properly, there should be no issue.

I get asked all the time, “What is the best way to make my shore power cord look new again?”

My answer is always the same, “Replace it!”

Far more important than how good your shore power cable looks, is how good it connects.

Pay attention to your cord when connecting it to the power post and vessel.

They have a twist lock.

When you twist it, you should feel the twist lock engage. The connector should sock up snuggly to the socket.

SCREW THE RING ON!

Make sure there is strain relief on the plugs at both ends.

Walk through any marina and you will see several instances where every boat movement is transmitted to the shore power connection.

There should be a loop of cable at each end, such that when the boat moves in her slip, there is absolutely no movement in the cable at either connection.

How long a shore power cord should last, depends how frequently and carefully it is used, (or abused).

For a marina slipped boat, that is frequently used, and proper strain relief on connections not exercised, the cable connectors may be wearing and loosening after only a year or two.

I see lots of 30A shore power cords, only 3 years old that should be scrapped.

Boater: “But those things are a hundred bucks to replace!”

Ramblinrod: How much will it cost to replace your boat, a couple boats each side of you, and this section of marina dock from here to there?”

The “Smart Plug”, certainly appears to be a better 30A @ 120 Vac shore power cable/socket design.

But they are not cheap.

My fear is that the average boater will not replace these until they are way, way, way overdue.

So what the marine retailer sees, is one Smart Cable sold for at least every 100 standard shore power cable sets sold.

Why?

Ignorance, laziness, frugality.



That seems like pretty good advice, but in my experience the cables last a lot longer than 3 years provided you don't nick or crush them.


As to the connectors, I think it's probably a real good idea to inspect them frequently and replace them on a schedule. The Euro blue plugs are well designed and cheap -- a nice combination which makes frequent replacement painless.



The Marinco twist connectors are just ghastly. I have 30 years of bad experience with them. They are completely non-waterproof, so one failure mode is hard rain gets inside them (been there, done that, how many times? ). Then besides that, the contacts are designed such that they lose their spring pressure -- you need to take them apart and re-bend the contacts regularly, or they stop pressing the contacts and you will burn them quick. Then all of that is compounded by the ridiculously small contact area, something like 20 times less than SmartPlug, which means that any slight imperfection, a little dirt or corrosion, a little loss of spring pressure, means they burn. How many burnt ones have I taken off my own and friends' boats. In my opinion, they are just totally unfit for purpose, not to say total crap, and I wouldn't have another one on any boat of mine. YMMV.


As to the SmartPlug -- I have less than a week of experience with it, so can't say for sure how good it really is, but it sure LOOKS good. It is beautifully made with really robust wire clamps with allen bolts (always use a sleeve!) and very elaborate waterproofing seals. My guess is this will last a long, long time. One downside besides the high cost not mentioned is that the plug is quite bulky. Maybe not noticeable on a fat 32 amp cable made for 110v, but makes a slender 230v cable noticeably more awkward to coil and store.
__________________
"Parce que je suis heureux en mer, et peut-ętre pour sauver mon ame. . . "
Dockhead is online now   Reply With Quote
Old 21-10-2019, 08:09   #51
Registered User

Join Date: Jun 2019
Location: Rochester, NY
Boat: Chris Craft Catalina 381
Posts: 43
Re: Shore Power Connections -- Again

I'll agree that the 30A Marinco plugs (NEMA L5-30 connectors) don't hold up well in a marine environment. The 50A plugs (NEMA L5-50 for 125V, L14-50 for 125/250V) hold up much better. The contacts are bigger, but still not huge due to the twist lock aspect. But they don't lose spring as readily due to the outer ring forcing better alignment and minimizing sideways pull on the contacts. They do still suffer from the water intrusion issue, however.
rslifkin is offline   Reply With Quote
Old 21-10-2019, 08:51   #52
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Helsinki (Summer); Cruising the Baltic Sea this year!
Boat: Cutter-Rigged Moody 54
Posts: 25,638
Re: Shore Power Connections -- Again

Quote:
Originally Posted by rslifkin View Post
I'll agree that the 30A Marinco plugs (NEMA L5-30 connectors) don't hold up well in a marine environment. The 50A plugs (NEMA L5-50 for 125V, L14-50 for 125/250V) hold up much better. The contacts are bigger, but still not huge due to the twist lock aspect. But they don't lose spring as readily due to the outer ring forcing better alignment and minimizing sideways pull on the contacts. They do still suffer from the water intrusion issue, however.

Why bother with all of that?


Shore power connectors should be waterproof and robust, with good mechanical strength, good strain relief, excellent waterproofing, good strong cable connections, and reliable contacts. Is that so much to ask??!! Is that such a rocket-scientific engineering challenge??!! What the hell business does a shore power connector have being used outdoors and on a boat if it's not even waterproof??


No wonder the pros simply give up and hard wire their shore power cords!


Surely there are decent connectors besides the expensive SmartPlug. Mastervolt make one in the Euro blue plug format:


https://www.mastervolt.com/products/...pe-32-a-230-v/


Even the El-Cheapo plastic blue plug inlet sold here:


https://www.force4.co.uk/force-4-flu...ug-16-amp.html


Is a huge leap forward from Marinco.


Surely there are other really good ones besides SmartPlug.
__________________
"Parce que je suis heureux en mer, et peut-ętre pour sauver mon ame. . . "
Dockhead is online now   Reply With Quote
Old 21-10-2019, 10:24   #53
Registered User
 
Auspicious's Avatar

Join Date: Jun 2003
Location: Chesapeake Bay
Boat: HR 40
Posts: 2,448
Send a message via Skype™ to Auspicious
Re: Shore Power Connections -- Again

Quote:
Originally Posted by Pete7 View Post
I try to ensure I connect the cable to the yacht first, then take the cable ashore. If I fall in or slip well I am holding a cable without any supply. If you connect the cable to the shore power first, or the cable is hard wired and then step on board, that cable could be live.
At the risk of being blunt, you're doing it wrong.

All the breakers should be off. Extra credit for using a voltmeter at the power pedestal - that's what the big boys do. Hardwired cable goes ashore and plugged in. Turn on power at the pedestal breaker. Turn on power at the inlet breaker. Switch the feed (if not automatic through inverter/charger - a different discussion). Check meters and polarity lights at your panel. Turn on the panel.
__________________
S/V Auspicious
AuspiciousWorks
Beware cut and paste sailors
Auspicious is offline   Reply With Quote
Old 21-10-2019, 10:55   #54
CF Adviser
 
Pelagic's Avatar

Cruisers Forum Supporter

Join Date: Oct 2007
Boat: Van Helleman Schooner 65ft StarGazer
Posts: 8,589
Re: Shore Power Connections -- Again

Quote:
Originally Posted by Pete7 View Post
Is this safe for general adoption by the masses?

It suggests picking up the shore power cable and taking it aboard, then making the connection with the boats supply.

I try to ensure I connect the cable to the yacht first, then take the cable ashore. If I fall in or slip well I am holding a cable without any supply. If you connect the cable to the shore power first, or the cable is hard wired and then step on board, that cable could be live.

Sure it might be switched at the shore and being safety conscious you checked before touching it, every single time. But you or a crew member only has to be unlucky once taking the cable aboard or making the connection.

Dockhead mentioned the blue European plugs and sockets, there is also a yellow 110V plug, which has a different lug position from the 240v so they can't be mixed. Ours last 5 to 6 years before they corrode. Thankfully they are cheap enough not to worry, just snip them off and start again. For a 16amp supply @ 240v which most shore power seem to be rated at they work well.

The way some folk mess about with shore power cables on the jetty is just scary at times. Another one glad to be 90% reliant on solar. The anodes last longer not connecting to shore power too.

Yacht end of shore power cable.
Hi Pete,
Like you, mostly solar now, but at a marina with no breeze, running the Aircons when its a humid 35°C is desired

Understand the safety concerns and if the masses are Darwinian, then someone will always get an award!

My own shore cable is rated at 60a, quite long and quite heavy.

The shore side pedestals normally.the same rating, but as you know those plugs are often in poor condition from stress

My normal practice is to take two wraps around the base of the pedastal for security before plugging in .

If disconnecting for day sail
boat breaker shut off, then shore breaker and cable unplugged from pedestal before disconnecting cable in engineroom and taking ashore.

When connecting .....the shore plug and breaker goes on last before checking onboard for proper power
(Murphy and I have a deal that I never try to tempt him)

With rats chewing on floating dock cable runs, shore power is a big liability so isolation transformer and dry and tight onboard connections is your best defense.

I do use those blue plugs for drydock work and for heavy loads like compressor or welding, but again. They are not waterproof if someone is hosing down the deck.

I prefer my cable going in via a dorade type air vent to make a dry connection in the engine room.
Pelagic is offline   Reply With Quote
Old 21-10-2019, 11:40   #55
Moderator
 
Pete7's Avatar

Cruisers Forum Supporter

Join Date: Aug 2009
Location: Solent, England
Boat: Moody 31
Posts: 12,233
Images: 14
Re: Shore Power Connections -- Again

Quote:
Originally Posted by Auspicious View Post
At the risk of being blunt, you're doing it wrong.

All the breakers should be off. Extra credit for using a voltmeter at the power pedestal - that's what the big boys do. Hardwired cable goes ashore and plugged in. Turn on power at the pedestal breaker. Turn on power at the inlet breaker. Switch the feed..... Turn on the panel.
That's pretty much what I am doing except the cable isn't hard wired. It uses the plastic socket Dockhead linked to earlier on the boat in a sheltered spot, one male, one female blue plug on the cable. We always take the cable with us when sailing, if nothing else so we can use it at the next location. There is no saying what will happen to it if left on our pontoon. Not uncommon to see cables dangling in the water.

The European pedestals have breakers normally in a little box low down, but no other switches. No one turns off the breakers when plugging in, they are always on even when unused. Hence connect to the boat first, then plug into the shore side power. The idea of a live cable on the pontoon which is then carried on to the boat is the worrying bit or a pedestal turned off but cable plugged in coiled nearby, someone then plugs into an adjacent socket and turns all the breakers on.

Of course we have an RCD, master switch on the panel and individual breakers with a voltmeter also on the panel, First IA when looking for faults is the voltmeter.

I hadn't seen a Marinco plug until Dockhead showed me a picture of one, at least Europe has something right. Now if we could just get the French to sort out their live and neutral and earth wiring so they are all the same and not reversed in some marinas we will be well away.

Pete
Pete7 is offline   Reply With Quote
Old 21-10-2019, 11:53   #56
Moderator
 
Pete7's Avatar

Cruisers Forum Supporter

Join Date: Aug 2009
Location: Solent, England
Boat: Moody 31
Posts: 12,233
Images: 14
Re: Shore Power Connections -- Again

Quote:
Originally Posted by Pelagic View Post
My own shore cable is rated at 60a, quite long and quite heavy.

The shore side pedestals normally.the same rating, but as you know those plugs are often in poor condition from stress

My normal practice is to take two wraps around the base of the pedastal for security before plugging in .
How do you coil that. We had 50m of 2.5mm 3 core on board when we bought her. Arms hurty coiling that lot. Swopped it out for 30m of 1.5mm 4 core but then we don't have big power demands. We might use 3a or even 4a if we are feeling extravagant with heat and light one of the advantages of a little boat I guess.

Those shore side pedestals do take a beating and normally placed near the edge of the pontoon. With a bit of practise well within striking range of a bow mounted anchor "ram". Not forgetting departing without unhooking the shore cable is a popular sport.

All excellent fun, so long as you are a spectator not participant
Pete7 is offline   Reply With Quote
Old 21-10-2019, 11:57   #57
Registered User
 
Auspicious's Avatar

Join Date: Jun 2003
Location: Chesapeake Bay
Boat: HR 40
Posts: 2,448
Send a message via Skype™ to Auspicious
Re: Shore Power Connections -- Again

Quote:
Originally Posted by Pete7 View Post
The European pedestals have breakers normally in a little box low down, but no other switches. No one turns off the breakers when plugging in, they are always on even when unused.

Would you follow lemmings off a cliff? Turn the breaker off. I've been to the EU, cruised there, and turned the breakers off. They work.
__________________
S/V Auspicious
AuspiciousWorks
Beware cut and paste sailors
Auspicious is offline   Reply With Quote
Old 22-10-2019, 02:19   #58
Registered User

Join Date: Aug 2017
Posts: 22
Re: Shore Power Connections -- Again

Quote:
Originally Posted by Dockhead View Post
The "80% Rule"? I never heard of such a thing. I always assumed that the ratings were for continuous use, and were calculated conservatively.


If what you say is true, it's a totally different situation. And would explain a lot of my experiences, so you may have made a significant contribution to my education


Now I'm going to have to read up on this. Learn something new every day.




Right off the bat: https://www.electriciansforums.net/t...80-rule.35406/

80% is correct. That's what most households realise charging their EV at rated power, cables and plugs getting really hot or (especially plugs) burn off.
Dirk01 is offline   Reply With Quote
Old 22-10-2019, 02:36   #59
Registered User

Join Date: Aug 2017
Posts: 22
Re: Shore Power Connections -- Again

Quote:
Originally Posted by tarian View Post
A poor response , thousands of boat fires every year, were is your link, and a breakdown of what caused them , facts makes sense your post does not
fires can be caused by gas, petrol, oil, diesel , electrical. dropping of a cigarette
what are the % of fires caused by thermal heating as you as the OP have told us that you worry about this but what is your fear based on ,
Or is it I read it somewhere or heard it somewhere like most rumours and that silly article reads like a poor magazine article from Hello

Poor arguments. One fire caused by overheated plugs is one to much.

On the other hand do it your way, hoping you're not the silly one who's boat is not the 0.0001% rate lit up boat.
Dirk01 is offline   Reply With Quote
Old 22-10-2019, 02:51   #60
Registered User

Join Date: Aug 2017
Posts: 22
Re: Shore Power Connections -- Again

Quote:
Originally Posted by sailcrazy View Post
followingI've never heard of "hard-wiring" the shore power cord in, and just pulling it out of the locker when you need it....eliminating the shore power plugin and receptacle all together. An interesting idea!

We've had that design on our last charterboat (in Croatia). With a hughe, very flexible cabel. It worked pretty well.
__________________

Dirk01 is offline   Reply With Quote
Reply

Tags
shore power

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Only one power cord is getting power from my shore power. Privilege Electrical: Batteries, Generators & Solar 10 11-09-2019 09:35
Portable Honda Gen to Shore Power- Can this power hot water electrics? simonpickard Electrical: Batteries, Generators & Solar 25 03-06-2019 08:30
Power Panel - Shore power light dmksails Electrical: Batteries, Generators & Solar 5 10-08-2017 11:02
Improving on Shore Power Connections Pelagic Electrical: Batteries, Generators & Solar 28 18-02-2015 12:03
Leopard 38: Shore Power Connections hikersailor Leopard Catamarans, Robertson & Caine 0 16-08-2014 17:48

Advertise Here


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 08:20.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
×

ShowCase vBulletin Plugins by Drive Thru Online, Inc.