--- On Thu, 11/11/10, Chris Smither <yachtakwaaba@...> wrote:


From: Chris Smither <yachtakwaaba@...>
Subject: Re: [Amel] Re: Shore Power Cables
To: amelyachtowners@...
Date: Thursday, November 11, 2010, 6:50 PM


 



Hi All,
   Fundamentally, for twice the voltage you need half the current to get the same power (Ohms Law - W=IxV), and as the thickness of the conductor determines the current carrying capacity, thus 120V (US) cables are generally thicker than 240V (rest of world) for the same required load.
   This is oversimplified, as slightly different rules apply with ac inductive loads, (motors etc), but it is a good "rule of thumb"
   If wires carrying loads get warm, then the first place to look is at the connections, as heat in wires is generated by high resistance and the plugs and sockets are the most probable culprits. Electrical cables transfer heat almost as well as electricity!. Clean water resistant contacts will eliminate most problems. ( I use lanolin grease - natural product and lasts well)
   If your wire is warm in the middle only, then you could have some damage, internally, at that point. Don't try to fix it - replace the cable!
   Hope this helps.

Mike
Santorin Akwaaba
Also retired electrical engineer
   

--- On Thu, 11/11/10, Danny and Yvonne SIMMS <simms@...> wrote:

From: Danny and Yvonne SIMMS <simms@...>
Subject: Re: [Amel] Re: Shore Power Cables
To: amelyachtowners@...
Date: Thursday, November 11, 2010, 8:19 PM

 

Hi there, thought I'd weigh into this with a comment, (question) that my understanding of the reason for larger boats being fitted with 24 volt systems is that they require smaller cables than 12 volt and given the distances and the loom sizes on the Amel it is the only way to go. I believe the same applies to 110 and 220, perhaps hence the smaller shore cable from Europe.  Any electician like to confirm or deny this? 

Regards

Danny and Yvonne

Ocean Pearl. SM299

--- On Fri, 12/11/10, Kent Robertson <karkauai@...> wrote:

From: Kent Robertson <karkauai@...>

Subject: Re: [Amel] Re: Shore Power Cables

To: amelyachtowners@...

Date: Friday, 12, November, 2010, 5:03 AM

 

Thanks, Craig.  That makes very good sense for the 110 cable.  I'm still not sure why we can get by with such a small 220 cable compared to what's recommended in the US, and why it makes a difference (or if it even does) if we're using EU 220 or US 220 to what size shore power cable we need.  Is it just the difference between EU 220 50Hz and US 120/240 60Hz?  If so that's a huge difference in cable size for a 9% difference in voltage and a 20% difference in Hz (the difference in Hz really doesn't alter the Amperage, does it?).  I don't know if I'm really as dumb as I feel about this stuff, but I get a different answer from every electrician I deal with...and now this one (who seems sharper than the average) is strongly recommending that I change the 220 shore power cable to a much larger one (~1inch dia) at great expense.  My gut tells me no, but I'm trying to get my head in line, too.

Thanks again to all.

Kent

SM243

KRISTY

[Non-text portions of this message have been removed]

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--- On Thu, 11/11/10, Danny and Yvonne SIMMS <simms@...> wrote:

From: Danny and Yvonne SIMMS <simms@...>
Subject: Re: [Amel] Re: Shore Power Cables
To: amelyachtowners@...
Date: Thursday, November 11, 2010, 8:19 PM







 









Hi there, thought I'd weigh into this with a comment, (question) that my understanding of the reason for larger boats being fitted with 24 volt systems is that they require smaller cables than 12 volt and given the distances and the loom sizes on the Amel it is the only way to go. I believe the same applies to 110 and 220, perhaps hence the smaller shore cable from Europe.  Any electician like to confirm or deny this? 

Regards

Danny and Yvonne

Ocean Pearl. SM299



--- On Fri, 12/11/10, Kent Robertson <karkauai@...> wrote:



From: Kent Robertson <karkauai@...>

Subject: Re: [Amel] Re: Shore Power Cables

To: amelyachtowners@...

Date: Friday, 12, November, 2010, 5:03 AM



 



Thanks, Craig.  That makes very good sense for the 110 cable.  I'm still not sure why we can get by with such a small 220 cable compared to what's recommended in the US, and why it makes a difference (or if it even does) if we're using EU 220 or US 220 to what size shore power cable we need.  Is it just the difference between EU 220 50Hz and US 120/240 60Hz?  If so that's a huge difference in cable size for a 9% difference in voltage and a 20% difference in Hz (the difference in Hz really doesn't alter the Amperage, does it?).  I don't know if I'm really as dumb as I feel about this stuff, but I get a different answer from every electrician I deal with...and now this one (who seems sharper than the average) is strongly recommending that I change the 220 shore power cable to a much larger one (~1inch dia) at great expense.  My gut tells me no, but I'm trying to get my head in line, too.

Thanks again to all.

Kent

SM243

KRISTY

































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-----Original Message-----

From: "Kent Robertson" <karkauai@...>
Sent: Thu, 11 Nov 2010 18:48:41 -0000
To: amelyachtowners@...
Received: 11-Nov-2010 19:49:04 +0100
Subject: [Amel] Re: Shore Power Cables

I LOVE this forum! To all who have chimed in, Craig, Richard, Gary and Serge...Thank you for your input. My head is now in line with my gut and I am comfortable leaving the wiring as-is. Gary, I will install a 220 monitor so I can keep track of what I'm actuall getting and using. It will also help to monitor the genset's output. I'll monitor the wire temp carefully and adjust my usage if it's getting a bit too warm. If I find I'm not able to use what I want to (not likely while in the temperate/tropical zones), I'll consider upgrading the shore power cables. I'll straighten out the cables if there's any excess and change the posts to busses, too, Serge.

Thanks again to all, happy sailing!
Kent
SM243
KRISTY

--- On Fri, 12/11/10, Kent Robertson <karkauai@...> wrote:


From: Kent Robertson <karkauai@...>
Subject: Re: [Amel] Re: Shore Power Cables
To: amelyachtowners@...
Date: Friday, 12, November, 2010, 5:03 AM


 



Thanks, Craig.  That makes very good sense for the 110 cable.  I'm still not sure why we can get by with such a small 220 cable compared to what's recommended in the US, and why it makes a difference (or if it even does) if we're using EU 220 or US 220 to what size shore power cable we need.  Is it just the difference between EU 220 50Hz and US 120/240 60Hz?  If so that's a huge difference in cable size for a 9% difference in voltage and a 20% difference in Hz (the difference in Hz really doesn't alter the Amperage, does it?).  I don't know if I'm really as dumb as I feel about this stuff, but I get a different answer from every electrician I deal with...and now this one (who seems sharper than the average) is strongly recommending that I change the 220 shore power cable to a much larger one (~1inch dia) at great expense.  My gut tells me no, but I'm trying to get my head in line, too.
Thanks again to all.
Kent
SM243
KRISTY

[Non-text portions of this message have been removed]








[Non-text portions of this message have been removed]

--- In amelyachtowners@..., Kent Robertson <karkauai@...> wrote:
" Hi, Craig. There are 3 A/C-Heating units that ... use 5.4 A each in heater mode, the water heater info says 3.2 A.  So if I'm running all of it at once, I'm up to ~20A, plus what the charger uses (3-7A)...still below the 30A circuit limit and well below the 50A limit."

Kent - Those are likely 220v ratings. Let's convert to 110.
5.4A + 5.4A +5.4A + 3.2A = 19.4 Amps:
19Amps X 220volts = 4268 watts:
4268 watts / 110volts = 35.6 Amps
That's quite a bit over your 30A 110v limit (and I didn't add in the charger) - no wonder it's hot.
 
Kent continued: "My ? really is about the size of the wiring not meeting ABYC standards. Is it your understanding that there would be any difference between using European type 220 vs US type 220? The 50A 220v shore power cords that are available in the US are huge compared to the 220 line on the boat. The 30A 110V cord is bigger than the 220 one, but still not what's recommended by ABYC."

Kent, First, the European 220 is at 50 Hertz and US 110v is at 60 Hz. Actually the US is more like 120/240. So the European system will deliver less power over a given time than the US. (That's why our refrigerator takes longer to cool in Europe than in the US.) More power in a given time = more heat = bigger cables in US. Plus, in general, I think US electrical standards are more conservative than EU.

Kent continured: " I'm not really worried about the boat, but still don't understand the differences between US and European 220 enough to be completely confident when an electrician is telling me the wires are too small to be safe."

Kent: Hope the above helps some. Hey, go south - turn off the heaters, throw out the anchor and have a ball! If it's chilly in the meantime, turn on your diesel heater.

Cheers, Craig

--- On Wed, 11/10/10, sv Sangaris <sangaris@...> wrote:


From: sv Sangaris <sangaris@...>
Subject: [Amel] Re: Shore Power Cables
To: amelyachtowners@...
Date: Wednesday, November 10, 2010, 12:34 PM


 



Hey Kent,
Sailing south you won't need the heaters - problem solved :-)

I'd guess the 110v feed is an add-on by the former US owner of Kristy, not original Amel, correct? What wattage are you drawing on your heaters - many are in the 1800w range. Sounds like you've got more than one - two would present 3600w which at 120v gives you the 30A limit of your cable - no wonder it's hot!

If you need the heaters until you go south, can you run a separate additional 110 line out to the dock for one of the heaters? ... or get a 220v heater?

Seems you really needn't rip into the Amel wiring at all.

Cheers,
Craig