Looks like I have avoided a fire

So our Monk is powered with a single 30 amp shore power chord. *For a little 36 footer perhaps doable. *I've noticed lately that when I unplug the shore power chord it is warm to the touch @ the boat connection. *We added a 2 burner electric cooktop to the new galley this winter. *A couple of years ago the previous owner had added the 2 HVAC units. *The boat has been around since 1983 and never caught fire but things change, eh? *

Anyway, this past weekend when we unplugged the boat to go anchor out for the night, I noticed that the chord was particularly hot and there was a slight burt rubber smell at the shore power chord and one of the legs of the plug in was discolored and brownish/black. *Hmmm...NOT good. *We anchored out for the weekend and I made sure to only use one major power item at a time late yesterday before we went home (i.e. only one HVAC at a time, only stove, etc.). *I have never had any breakers trip ever. *Just to be safe I had my friends at the service department go through the electrical today to see what we needed to do. *I figured we would have to convert to twin 30 amp service. *Well...come to find out, I am lucky a fire never occurred. *The reason a breaker never tripped is that the main panel breaker is 50 amp not 30 amp! *On top of that, the wiring between generator and panel is undersized for the load. *I don't know if the boat came factory with a 30 amp or if the previous owner installed the 50 amp breaker but it basically was set up to be able to catch fire before a breaker would trip.

After discussing the options and looking at the work that is required to do twin 30 amp or single 50 amp, we have decided we are going to convert the boat this week to single 50 amp service. *I will have to buy one of heck of an expensive new 50 amp shore power chord but it will be a lot less wiring and work on the boat to convert to 50 amp. *My previous boat was equipped with a single 50 amp chord so I am not so much looking forward to that big old heavy chord but it beats burning to the ground. *It is frightening to think how long the boat has been set up with a 50 amp breaker with just a 30 amp service. *Over the years of the additional electrical devises it only stands to reason that something needed to be done but the panel had plenty of breakers to add the additional items. *A smarter person would probably have known something was up but I rarely am accused of being smart. *

Anyway...glad nothing happened beyond a discolored shore power chord and not even a spark on the boat so we caught it in time and will be fixed before the weekend. *In addition to the new 50 amp shore power service, we are going to rewire between generator and panel to make sure we are 100% safe regardless of our power source. *I am just glad we figured out everything in advance.

The moral of the story- if you own or are buying an older trawler, regardless of the build pedigree (or lack thereof where applicable), particularly if there have been any significant changes in the electric configuration/equipment, make sure that all breakers and wiring is properly sized. *I've had multiple marine certified electritians go through my boat previous to this and no issues found and none found by the surveyor so it is proof that sometimes you, as the owner or buyer, need to ask direct and specific questions in an intentional manner during your purchase process or refit process to make sure past wrongs are discovered and made right.

THE GOOD news is that a new slip opened up in our marina with a roof that is 2 feet taller that we are moving the boat to so I no longer have to lower my mast every time I come in or out of the slip like our current one!

A little luck can be worth a lot! Glad you found it.

First thing I did was check out Scout's panel when we got her home. Check the photo below. Surveyor didn't catch it either.

As a Brit with a newly acquired boat in the USA I read this with interest as I'm still getting my head around your 110V systems and USA connection options with more permutations than I can count. We have 2 x 30A cords and boat inlets plus 1 x 50A set at 110V not 220/240V. I was advised that for ease of handling (cord weights) and lower cost to have 2 x 30A cords and a 'Y' connector to connect them to 50A on shore. You might find that adding a second 30A inlet on the boat and separating out some AC circuits to run on that would be good?

Cords apart, if you were plugged in to a 30A shore socket I doubt you could get 50A regardless of the breaker on the boat because the shore trips would go, not to mention everyone would be trying to get more amps per buck if like use the supply cost is fixed by cord size not metered! Breakers are generally higher rated than the service rate too aren't they otherwise they would keep tripping, especially as a momentary surge load like aircon cut in?

"... one of the legs of the plug in was discolored and brownish/black."

The condition described is more indicative of a high resistance connection than an overload. A poor contact between the blade or wiper of the discolored leg created a high resistance and very high local temperature. While the amount of heating is related to the load on the boat, it was not caused by a general overload as your post seems to imply. The same situation most likely would have occured even if a 30 amp breaker was installed.

What was the rating of the breaker on the dock pedestal?

I am plugged into a 50 amp shore power connection via a 30 amp to 50 amp splitter.

Woodsong wrote:
I am plugged into a 50 amp shore power connection via a 30 amp to 50 amp splitter.

Click to expand...

Something to think about when you do that is that an arc fault at the boat connection can burn the boat down even if the only thing "on" on the boat is a 5W nighlight.

Your shore power cord and*connectors are rated for 30 amps but are supplied by a 50 amp breaker,*everything**between the pedestal and*the boat's main breaker is unprotected.

In the process of installing an isolation transformer, I discovered that my 30A breaker, which was the right size, had the hot lead paralleled across both breakers, rather than switching both the hot and the neutral.** In effect, I had a 60A breaker.* So, your right, if you have an older boat, it's worth poking around, even if everything is working.

The one I'm still trying to figure out is why the PO intentionally kinked the vent line for the holding tank and held it kinked with a tie wrap!* I only discovered this one by accident because of its difficult to access location.

Tony,

Glad to hear you found it without further damage or risk to you and yours. I had a similar discovery due to a weakened connection at the external plug which overheated the plug and cord on my 30A connection. The cord was very warm to the touch and starting to weld itself onto my plug as it was tough to remove initially.

I replaced the external plug, the internal wiring to my CB panel and the cord. Now all is well, but I pay closer attention to the cord temps as a matter of routine pre-departure checks.

Ain't owning old boats fun? Think of all the new skills we're learning!

Hope you enjoy the new slip. What 's that mast for anyway? It sure looks nice. Are you going to add a sail like mark pierce? Can you use it for deploying a dinghy?

TWO 120v/30A cords will NOT bring in the power of a 240V 50A cord.

The 240/50 can take 50 amps per leg. That is (2) legs of 50A at 120V.

the 120/30 is only 30A per leg.

Each leg in the boat must be OK with either 50A or 30A .

IT is not a matter of just getting a different power hose and deck fittings.

FF wrote:
TWO 120v/30A cords will NOT bring in the power of a 240V 50A cord.

The 240/50 can take 50 amps per leg. That is (2) legs of 50A at 120V.

the 120/30 is only 30A per leg.

Each leg in the boat must be OK with either 50A or 30A .

IT is not a matter of just getting a different power hose and deck fittings.

Click to expand...

*Not sure if this was related to my comment about 2 x 30A cords.* In our case and chosen marina (not there yet)*there seems to be an option of taking 50A at 110V split with a 'Y' connector from a 50A shoreside socket.* I belive this comes from a* 415V 3 phase marina supply circuit to the docks, split to give 208V/50A outlets*which can be further split to give 110V (nominal, really 104V max) and 50A via a 'Y' connector and 2 x 30A cords to on board* Like I said your systems have a really confusing array of options!*

I've replaced many shore power cords and boat side power inlets after severe cord end melt downs. Unfortunately, the reason for the melt down in many cases is nothing more than laziness (or ignorance, in the case of willing guests with good intentions, but lack of knowledge) While the Marinco system(most common one out there) uses a twist lock connection, we all know that it comes with the screw on locking ring as well. Many times, when I have asked the customer if they use the ring, the answer is "not always". Boat and dock movement, coupled with the weight of the cord itself are always working against the contacts. It doesn't take long, for the contacts to start to get warm if they are trying to pass 30 amps with minimal blade contact. Eventually the combination of minimal contact, increased heat and boat movement evolves into a constant make and break connection that only accelerates the degradation, not to mention can be hard on inverter transfer switches and other electronic devices that are cycling on and off constantly.

I have seen a new style of boat side connection, (brand escapes me) orange in color I believe that has what seems like a very positive connection. The problem is that most marinas are entirely wired t suit Marinco style power cords, so the dockside ends will not be changing all that quickly. The most likely interim fix will be hybrid cords with Marinco dockside ends and the newer brand boat side end.

bobc wrote:I discovered that my 30A breaker, which was the right size, had the hot lead paralleled across both breakers, rather than switching both the hot and the neutral.** In effect, I had a 60A breaker.*
You might want to review your electrical laws.

Click to expand...

*

Robin wrote:

Click to expand...

*Not sure if this was related to my comment about 2 x 30A cords.* In our case and chosen marina (not there yet)*there seems to be an option of taking 50A at 110V split with a 'Y' connector from a 50A shoreside socket.* I belive this comes from a* 415V 3 phase marina supply circuit to the docks, split to give 208V/50A outlets*which can be further split to give 110V (nominal, really 104V max) and 50A via a 'Y' connector and 2 x 30A cords to on board* Like I said your systems have a really confusing array of options!*

Is this marina in the U.S.?* I don't think 415V 3 phase is used here, but perhaps that has changed.* Seems like there would be lots of transformers involved to do what you are suggesting.

Woodsong, the size of the main breaker is relevant only as it relates to the wire size from the plug or genset to the main buss.* It would not have tripped even if it were 30 amps since the fault was upstream and resistive.* The breaker on the pedestal was 50 amps, the cord 30 amps, but it didn't trip either because even a 1 amp resistive load is quite sufficient to cause a fire.* Once things start melting, the pedestal breaker probably would have tripped but the fire is already under way at that point.

Sounds like you are fixing it all anyway, and it is good advice for anyone with a boat that had a PO to match the wire size downstream from the breakers to the rating of the breakers, as well as the wire size upstream from the main breaker to match the rating of that main breaker.*

Why some marine breaker manufacturers do not put the rating of the switch on the front side is a mystery to me, but it that is the way it is with some.

Delfin wrote:Robin wrote:

Click to expand...

*Not sure if this was related to my comment about 2 x 30A cords.* In our case and chosen marina (not there yet)*there seems to be an option of taking 50A at 110V split with a 'Y' connector from a 50A shoreside socket.* I belive this comes from a* 415V 3 phase marina supply circuit to the docks, split to give 208V/50A outlets*which can be further split to give 110V (nominal, really 104V max) and 50A via a 'Y' connector and 2 x 30A cords to on board* Like I said your systems have a really confusing array of options!*

Is this marina in the U.S.?* I don't think 415V 3 phase is used here, but perhaps that has changed.* Seems like there would be lots of transformers involved to do what you are suggesting.

*

Yes it is in Florida.* I was so confused I looked up in Nigel Calders Boat owners Mechanical & Electrical book and he explained it there, saying some marinas used it as a cheaper way of*getting power around long distances*to*the docks.* It isn't available at 415V but is split in the shoreside supply box to give 208V/50A outlets.* I questioned where this figure 208V came from and this was where, it being half of 415V from the 3 phase cable.* In our case we have a slip booked with a 208V/50A connection, we only want 110V so to get that we apparently can use a 'Y' connector 50A plug into the shoreside box and 2 x 30A cords from the 'Y' to on board.* Marineco catalogue shows different plugs/sockets combinations to take off 110V (104V in this case to be more precise) from a 50A connection as opposed to 220V/50A so presumably this prevents any mistakes???*

*

Like I said I find it very confusing compared to Europe's simple 220V for all system, not to mention the cable sizes being so much smaller.* The smaller currents from the higher 220V also are much less prone to causing the connection burning described.

Robin wrote:
I belive this comes from a* 415V 3 phase marina supply circuit to the docks, split to give 208V/50A outlets*which can be further split to give 110V (nominal, really 104V max)

Click to expand...

There is no 415V supply. The system you describe almost certainly originates in a 3 phase 4 wire wye connected*transformer which provides 120V and 208V.

Voltage between phases is 208, voltage between a phase and neutral is 120 volts, not 104,*because 120*sq/rt of 3 = 208.

Robin wrote:

Click to expand...

*

Yes it is in Florida.* I was so confused I looked up in Nigel Calders Boat owners Mechanical & Electrical book and he explained it there, saying some marinas used it as a cheaper way of*getting power around long distances*to*the docks.* It isn't available at 415V but is split in the shoreside supply box to give 208V/50A outlets.* I questioned where this figure 208V came from and this was where, it being half of 415V from the 3 phase cable.* In our case we have a slip booked with a 208V/50A connection, we only want 110V so to get that we apparently can use a 'Y' connector 50A plug into the shoreside box and 2 x 30A cords from the 'Y' to on board.* Marineco catalogue shows different plugs/sockets combinations to take off 110V (104V in this case to be more precise) from a 50A connection as opposed to 220V/50A so presumably this prevents any mistakes???*

*

Like I said I find it very confusing compared to Europe's simple 220V for all system, not to mention the cable sizes being so much smaller.* The smaller currents from the higher 220V also are much less prone to causing the connection burning described.

I know they use 415v 3 phase outside the U.S., but hadn't heard of it being available here, but it clearly is.* Typically, from a single leg to neutral you'll measure 240V, not 208V, so I am not sure what is going on there.* I also have no clue how you would access 120 volt from a 415 V 'Wye' 3 phase configuration without a step down transformer.* I believe you'll find 240V to ground from 2 legs and 415V from the high leg or across the 240V legs.* Been a while since I wired anything with 3 phase, and then we only used a 240 V Delta configuration where you had 120V to neutral from 2 legs and 240V to neutral from the high leg to neutral or across any 2 legs together.* Confused yet?*

Get a voltmeter and measure what's available.* If it is only 208V, that might be a problem with some motors if you don't have a transformer on board.*


-- Edited by Delfin on Tuesday 23rd of August 2011 02:19:18 PM

RickB wrote:Robin wrote:
I belive this comes from a* 415V 3 phase marina supply circuit to the docks, split to give 208V/50A outlets*which can be further split to give 110V (nominal, really 104V max)

Click to expand...

There is no 415V supply. The system you describe almost certainly originates in a 3 phase 4 wire wye connected*transformer which provides 120V and 208V.

Voltage between phases is 208, voltage between a phase and neutral is 120 volts, not 104,*because 120*sq/rt of 3 = 208.

*Thanks!* I think that makes sense and I'll try and get my head around how it affects us!* We are being offered a 208/50A connection but we want just 110V.* The charges*listed by the marina are $160/month for 208V and $80 for 110V split from a 208V socket.* I'm hoping we can use a 'Y' connector to take two 30A size*cords from the socket to give us 50A total on board at 110V and the $80/month rate, does that sound like I've got it right?* Two 30A cords direct would be $144/month but that connection isn't available on the slip on offer currently, plus we don't need 60A as probably 40A would do, one 30A is just a bit short of running all.

Again, there is no 415V supply.The normal house supply is a 120/240 V, single-phase, three-wire grounded system. Voltage between L1 and L2 is 240V, between either Leg and neutral is 120. This is supplied from the pole mounted transformer or a surface mounted box in some locations where the supply is underground.

In commercial or light industrial areas (such as a marina) the power supplied is likely to be three-phase 208Y/120 V or in rare cases 240/120 V. In areas where the consumers include a lot of motor loads the common three-phase system voltages are 208Y/120 V and 480Y/277V. The 277V system is used for lighting, particularly flourescent or gas discharge systems. These facilties normally use transformers to convert 480 to 208 and 120 for convenience outlets.

208 volts is within the tolerance limits for 230 volt rated motors. There are no problems related to using a 220 or 240 volt motor on 208 volts. Read the nameplate, most of them will say 208-230 volts.

*


-- Edited by RickB on Tuesday 23rd of August 2011 05:26:58 PM

RickB wrote:
Again, there is no 415V supply.The normal house supply is a 120/240 V, single-phase, three-wire grounded system. Voltage between L1 and L2 is 240V, between either Leg and neutral is 120. This is supplied from the pole mounted transformer or a surface mounted box in some locations where the supply is underground.

In commercial or light industrial areas (such as a marina) the power supplied is likely to be three-phase 208Y/120 V or in rare cases 240/120 V. In areas where the consumers include a lot of motor loads the common three-phase system voltages are 208Y/120 V and 480Y/277V. The 277V system is used for lighting, particularly flourescent or gas discharge systems. These facilties normally use transformers to convert 480 to 208 and 120 for convenience outlets.

208 volts is within the tolerance limits for 230 volt rated motors. There are no problems related to using a 220 or 240 volt motor on 208 volts. Read the nameplate, most of them will say 208-230 volts.

*

Click to expand...

*I'm not sure what you mean when you say there is "no 415V supply."* It is a common 3 phase configuration worldwide, but less so in the U.S.

Running a 230V motor on 208V is not recommended although some motors are wound to accept 208-230V.*

Wikipedia:* "Attempts to use the more common 120/240*V equipment intended for split-phase distribution may result in poor performance since 240*V heating and lighting equipment will only produce 75% of its rating when operated at 208*V. Motors rated at 240 V will draw higher current at 208 V; some motors are dual-labelled for both voltages."

The main problem is that the 230/240V motor run on 208V will run a lot hotter and not last as long.* Most trawlers run by folks on this forum will not have 230V motors in any case, and trying to run a 115V motor on 104V will also produce similarly unsatisfactory results.

Since 415V 3 phase does not produce 208V from any leg, I'm not sure why the marina says that is what they are getting from their 415V supply.*

Delfin wrote:

The main problem is that the 230/240V motor run on 208V will run a lot hotter and not last as long.* Most trawlers run by folks on this forum will not have 230V motors in any case, and trying to run a 115V motor on 104V will also produce similarly unsatisfactory results.

Since 415V 3 phase does not produce 208V from any leg, I'm not sure why the marina says that is what they are getting from their 415V supply.*

Click to expand...

There is no 415 volt supply in the US, we are talking about a US marina. They obviously don't know what their supply voltage is.

There is no 104 volt supply either. That number appears to have come from a poster thinking that 208 volts between legs would supply half that between a leg and ground or neutral. AC electricity doesn't work that way even though the common use of 240/120 supplied by a center tap transformer seems to the unitiated that it does.

There is a big difference between resistive heating loads and motor loads. A 230 volt rated moter (which most are) will happily operate on 208 and most state that on the nameplate. All this information is readily available from manufacturers and suppliers. Repeating old wive's tales and nonsense heard on the dock only confuses people more. Look it up, read an electrical power text, look at motor ratings.


-- Edited by RickB on Tuesday 23rd of August 2011 07:10:06 PM

RickB wrote:Delfin wrote:

The main problem is that the 230/240V motor run on 208V will run a lot hotter and not last as long.* Most trawlers run by folks on this forum will not have 230V motors in any case, and trying to run a 115V motor on 104V will also produce similarly unsatisfactory results.

Since 415V 3 phase does not produce 208V from any leg, I'm not sure why the marina says that is what they are getting from their 415V supply.*

Click to expand...

There is no 415 volt supply in the US, we are talking about a US marina. They obviously don't know what their supply voltage is.

There is no 104 volt supply either. That number appears to have come from a poster thinking that 208 volts between legs would supply half that between a leg and ground or neutral. AC electricity doesn't work that way even though the common use of 240/120 supplied by a center tap transformer seems to the unitiated that it does.

There is a big difference between resistive heating loads and motor loads. A 230 volt rated moter (which most are) will happily operate on 208 and most state that on the nameplate. All this information is readily available from manufacturers and suppliers. Repeating old wive's tales and nonsense heard on the dock only confuses people more. Look it up, read an electrical power text, look at motor ratings.

*

*The poster has his answer.* Just tell the marina that they don't know what their electrical service is.* Reference RickB, and who knows, he may be right.

230V motors will not "operate happily" at 208V.* This is not dock talk/old wive's tales*as you suggest, but simply a fact of physics.* I suggest you take your own advice and look at any motor supplier's offering, for example Grainger.* About 1/7th of their motors are dual rated for 208/230V because it is not the norm for single phase motors.* All other motors are rated at 230/240V and while they will turn at 208V or 150V, they won't last as long.* On the Grainger site, they have 54 skus for 208/230 volt single phase motors.* They have 373 skus for 230v motors that aren't deisigned to run on 208V.* To recommend that there is no material difference between these two configurations is not particularly helpful, or correct, however boldly you assert it.* Perhaps you are confusing single with 3 phase motors?* 208/230 3 phase are standard, but not present on small trawlers.

I also took your advice in looking this up in an "electrical power text".* Here is the reference I found:

Low voltage can lead to overheating, shortened life, reduced starting ability, and reduced pull-up and pullout torque. The starting torque, pull-up torque, and pullout torque of induction motors all change, based on the applied voltage squared. Thus, a 10% reduction from nameplate voltage (100% to 90%, 230V to 207V) would reduce the starting torque, pull-up torque, and pullout torque by a factor of .92.9. The resulting values would be 81% of the full voltage values. At 80% voltage, the result would be .82.8, or a value of 64% of the full voltage value. What does this translate to in real life? Well, you can now see why it's difficult to start "hard-to-start" loads if the voltage happens to be low. Similarly, the motor's pullout torque would be much lower than it would be under normal voltage conditions.

*

Yawn,

You are so predictable Delphin. You would argue that it was night at noon if I said it was daylight.

The old "wrestling with pigs" thing pretty much covers any discussion where you are involved. See you around.

*

And for those who are interested:

http://www.motorsanddrives.com/cowern/motorterms11.html


-- Edited by RickB on Tuesday 23rd of August 2011 08:24:10 PM

RickB wrote:
Yawn,

You are so predictable Delphin. You would argue that it was night at noon if I said it was daylight.

The old "wrestling with pigs" thing pretty much covers any discussion where you are involved. See you around.

Click to expand...

*What is predictable is your mix of good advice based on wide experience and knowledge randomly conjoined with completely errant and erroneous nonsense.* The problem is that it occasionally takes an interpreter to separate the two.* Glad to be of service.

And I wouldn't agrue that night is day, but would note that there is a reason why motors to be run on 208 volts are wound for 208 voltage.*

Now now....
Don't make me light YOU guys on fire!
Play nice now!

*



*

*


-- Edited by Keith on Wednesday 24th of August 2011 04:54:46 AM

Maybe if some of us took a short vacation to a nice B&B it would all be OK.* Like on your own island for a while.* http://www.ebls.org/




-- Edited by markpierce on Tuesday 23rd of August 2011 09:05:28 PM

Maybe if some of us took a short vacation to a nice B&B it would all be OK.* Like on your own island for a while.

*

----------------------------------------------------------------

Only thing I know is, I have 120 volts off the dock and 120 volts out of my gen set. *So life is good!!

p.s. Nice little Island cottage, I wonder if they have 120 volts or something else?*

Edelweiss wrote:
Maybe if some of us took a short vacation to a nice B&B it would all be OK.* Like on your own island for a while.

*

----------------------------------------------------------------

Only thing I know is, I have 120 volts off the dock and 120 volts out of my gen set. *So life is good!!

p.s. Nice little Island cottage, I wonder if they have 120 volts or something else?*

Click to expand...

*I think I see a plume of smoke coming out of the building to the right.* So I suspect they are running 240V motors on 208V.....

RickB wrote:bobc wrote:I discovered that my 30A breaker, which was the right size, had the hot lead paralleled across both breakers, rather than switching both the hot and the neutral.** In effect, I had a 60A breaker.*
You might want to review your electrical laws.

Click to expand...

*

*With two breakers in parallel, the current is split half the current through one, half through the other (assuming equal resistance of the contacts).* This means the combination can pass a total of 60A with each breaker conducting 30A.* I think I'm on safe ground here.