a cautionary note on Seaward water heaters

mitiempo · Jul 9, 2015

Gunni said:
.....I would expect a manufacturer of an electrical appliance to anticipate a malfunction as simple as a loose connection or resistant corrosion leading to electric overload and fire. And I would expect that a burned up conductor would have radically raised the resistance in the system and quickly sent the current beyond 15 amps - tripping the breaker. So, where was this situation going to terminate by design protection?

The breaker is not likely to go from resistance alone. Same as with shore power cords - rarely does the breaker go when a wire burns. On load alone a breaker will handle a fair amount of current over its rating. As an example my 20 amp shore power breaker - on the dock - can handle 26 amps continuously and pops at 27 amps. In a short circuit situation the breaker will go instantly.

Older wiring hardens, possibly corrodes a bit, and resistance increases. Add a possible loose connection and it gets worse, the product being heat. All older wiring, on any item, should probably be checked for loose connections and hardening of the wire. Water heaters are not the cause, just one example.

I have not heard of any issues with Seaward water heaters relating to the wiring. They are a budget water heater - the budget part is the tank, not the wiring. I installed a Seaward water heater 2 weeks ago and found the wiring to be properly done. My connections were properly crimped with heat shrink connectors.

I don't see how one can try to blame Seaward for a malfunction that didn't occur for 12 years, especially in the marine environment.

Were the connections properly crimped and covered with heat shrink?

mz4wheeler · Jul 9, 2015

First of all, it is unlikely that this would have caused the boat to catch on fire. This is the reason why all electrical connections (even in a house) must be in a terminal box, which contains and limits any fire or overload.

Believe it or not, your water heater is still usable, you CAN replace any/all the items:

http://www.defender.com/product3.jsp?path=-1|51|2234308|2234315&id=2395661
http://www.defender.com/product3.jsp?path=-1|51|2234308|2234315&id=2302346
http://www.defender.com/product.jsp?path=-1|51|2234308|2234315&id=2289522

And as long as you properly wire it up, with new wires [duh].

My guess is not corrosion because these connections are in a terminal box and should be protected.

Also, it is a clue that the black wire attached to the element is burned to a crisp, but the white wire opposite is not. This must mean that (possibly) the left connection to the element was somehow shorted to ground (the metal water heater itself), causing high current, which made the thermostat super hot, which eventually melted/shorted the wires against it (white wire).

Maybe the black wire was pressed too hard against the metal water heater when the cover was attached? Also, check the resistance from each terminal of the element to the metal (the big bolt).

Has the hot water been super hot lately?

walt · Jul 9, 2015

Just out of curiosity..

Was the wiring for the water heater (or the air conditioner) just copper or tin plated copper? I cant tell from the pictures but maybe you remember when you snipped the wires to remove the heater..

What wiring (plated or not) is "normal" for marine installs? Tin plated is "correct" but do you always find tin plated copper used by manufactures..

(I have a 25 year old Mac.. and uh... I dont think they used tin plated wire..lol)

Gunni · Jul 9, 2015

mz4wheeler said:
First of all, it is unlikely that this would have caused the boat to catch on fire. This is the reason why all electrical connections (even in a house) must be in a terminal box, which contains and limits any fire or

Yes, the Seward HW heater wiring is contained within a metal shroud on the side of he appliance. A sort of lightweight box I suppose. Can I assume that had Bob's HW heater continued on its path to immolation the wiring would have melted, and fused, causing the short that would have tripped the breaker? That would be my question to Seaward, who has designed, tested, certed and sold a zillion of these things. This cannot be the first time that this has happened. What is the failure mode?

mz4wheeler · Jul 9, 2015

Gunni said:
Can I assume that had Bob's HW heater continued on its path to immolation the wiring would have melted, and fused, causing the short that would have tripped the breaker? What is the failure mode?

You nailed it. Absolutely, 100%, this SHOULD have tripped the breaker. The failure mode must have been the circuit breaker was too big (or nonexistent) for THIS water heater.

Here is the lesson here (and to me). Like most boats, I have a dedicated circuit breaker for my water heater. Great. Do I know what amperage it is? No (my response). What is the recommended breaker for THIS water heater?

So, whatever manufacture recommends (amperage, fast/slow trip, etc.) the breaker should match.

Will I change mine? Probably not.

Allan12210 · Jul 9, 2015

Bob 04 H260 said:
I think the real take away here is, don't leave the hot water tank on when you are not on the boat or sleeping. I think Seaward should tell the owners that. I don't think this is a common problem or it would be well known. Who knows maybe this post will generate some others who had similar problems but never reported it.

Bob

Last January my friends in our marina were staying overnight on their Hunter 290. About 4:00 in the morning their new little dog started pestering them. My friend said his first inclination was to just roll over and go back to sleep. Suddenly, he said he was extremely alert and realized the cabin was full of smoke. They grabbed the dog and got out as it really started to billow. From outside the boat behind the nav station they could see the orange glow of the fire through the fiberglass. After pulling the shore power at the pedestal all he could do was spray water into the cabin via the companionway. There was no way to get back into the boat because of the dense smoke. Even though the nav panel was in place, the fire went out. I think that little dog saved their lives.

In talking to them, the only thing they were using was the water heater and a small ceramic heater set on low.With the extent of the damage, no one could figure out what was the root cause of failure or understand why the breaker didn't trip on the boat or on shore. I would venture to guess that the combination of those two appliances was close, but still less than the 30 amp mains (they were both on separate, protected circuits). All I know is that they were really lucky.

The insurance company offered to repair the boat, but they turned it down as everything smelled so bad they didn't believe it would ever be possible to recover from that. Then the insurance company settled for $40,000 but wanted them to keep the boat. My friend thought it would cost a lot to dispose of what wasn't salvageable and could be sold, so he told the insurance company to take it away. It took them a couple of months before they towed it away, and we have no idea what happened to it.

In our case we never sleep with the water heater on and we bought a fire/smoke detector and CO monitor for ours. We also have a little dog.

woodster · Jul 9, 2015

Bob 04 H260 said:
Good points, from the Seaward Owners manual,

"Connect the electrical supply by a qualified electrician. The electrical supply shall be
permanent wiring, armored cable or conduit, per national electrical code NFPA 70, with
a minimum capacity of 1500 watts.
On 120 volt circuits, use a UL approved 15 amp circuit breaker. On 240 volt circuits,
use a 10 amp approved circuit breaker per leg. "

Ours was wired through a 15 Amp breaker.

If our breaker is faulty and allowed too much current going through the circuit why did only these few sections of black wire get red hot and melt the insulation ? Why not the white return wire, why not the black wire in the 14/3 supplying the current from the panel ? I am convinced there was something wrong with those few pieces of wire, they developed enough resistance to get red hot with the 12 amps the heater element allowed to go through them.

I've pretty much given up trying to figure out why it happened and was never trying to blame anyone. When I contacted Seaward about the problem I told him right away I was not expecting a warranty claim or free hot water tank. I just thought they should know about it and probably tell owners not to leave them on when sleeping or the vessel is unattended.

Bob

i am thinking ac does not make a round trip like dc ...so that may be why the white wire didn't fry like the black

mitiempo · Jul 9, 2015

mz4wheeler said:
You nailed it. Absolutely, 100%, this SHOULD have tripped the breaker. The failure mode must have been the circuit breaker was too big (or nonexistent) for THIS water heater.

Here is the lesson here (and to me). Like most boats, I have a dedicated circuit breaker for my water heater. Great. Do I know what amperage it is? No (my response). What is the recommended breaker for THIS water heater?

The breaker would only trip IF the hot wire either shorted to the case of the heater or burned through either other wire (neutral or ground) as it melted. If this short occurred any breaker would trip - even an over sized one. A wire that gets hot through resistance will rarely trip a breaker. I see it on shore power inlets and cords all the time.

All U Get · Jul 10, 2015

woodster said:
i am thinking ac does not make a round trip like dc ...so that may be why the white wire didn't fry like the black

Similar thought here, was the water warm during the last use? I don't know how the heating element fails. Is it slow or a quick change. My logic sees the AC coming through the black side with the heat dissipating in the heating element, cooled by the water, and returning on the white. The breaker being on the black side sees a rise in current, but not enough to trip. The little black wire takes the heat.

The block heater on my backhoe decided not to work when it was 400 below zero this past winter. I plugged it in, instant trip. Tried it again, tripped again. The extension cord was pretty warm by then even with the wind chill. In my house the ground is near the panel, on a boat it is on shore some distance away. My fuzzy logic says that's why it takes so long to trip on a boat.

All U Get

Maine Sail · Jul 10, 2015

Guys AC simply means "alternating current". This means that the white wire (AC Neutral) and black (AC Hot) wire are still carrying the identical current. If you have a 1500W element and use Ohm's Law;

1500W ÷ 120V = 12.5A

The white wire and black wire are going to be carrying 12.5A and you can easily confirm this with a clamp meter.

This looks like a classic case of high resistance. The 12.5A current won't change, unless the source voltage did, but the ability of that section of wire to carry such current has been compromised so the wire, terminal, switch etc. gets hot. As it heats the heat travels down the wire a bit and can easily melt the insulation within a few inches of the high resistance. Only if the bare "jacket free" black wire now shorts to ground will the circuit breaker trip. A circuit breaker won't trip under high resistance because it is still only delivering 12.5A and this is well below its trip range.

Think of it this way.

Cut the black 14GA wire to a water heater and insert a 3' long piece of 26GA wire....... Do you think that 3' piece of 26GA inserted into that circuit can carry 12.5A without getting hot. It is still going to carry 12.5A until it either melts/fuses, shorts or burns the boat down...

We seem to only be focusing on the wire but the thermal switch or t-stat also interrupt the black wire and can also be a source of high resistance....

Rick486 · Jul 10, 2015

walt said:
It is odd that only the black wire is burned up - as you said, there must be two conductors involved in the current flow so why only the black wire. Normally the white wire would have identical current to the black wire.

If you take an ohm meter and measure the resistance between the green wire and the white or black wires, what do you get? You should measure an open between the green wire to both the black and white. Sounds like you have the unit with you so this should be easy?

If for example you measured a low resistance between the white and the green, you could have had a fault that resulted in the current in the black wire returning through both the white and the green wires - twice the wire so they don’t show the burn. Note, the green wire should show a low resistance to the metal chassis - but that should be the only connection.

Second thing is you said there is a 15 amp fuse in the line. Is this the fuse on your boat or is the fuse in the marina? Not that it matters.. but just curious.

It’s also somewhat odd that the air conditioner case also looks like it was the black wire that mainly was involved in burning up. Even though normally the black and the white wires carry equal current (for 110 VAC in the US), the white wire is normally always very close to the earth potential - very close to the green wire potential. It is the black wire that has the voltage on it with respect to the earth potential. Try measuring this at a 110 VAC socket (carefully) with an AC volt meter from green to white (measures near zero) and green to black (measures 110 VAC). Maybe because the black wire has a potential on it with respect to earth potential, it and its connections are more susceptible to corrosion just from being in that marine environment - but that is a complete speculation on my part..

This is what bothers me about this incident. Don't we all have the 20 amp isolation breaker in line with the shore power plug? Then we have the breaker on the AC panel in the boat which is said to be 15 A? As Gunni said above, it would seem that the black wire saw more than 15 A to melt the insulation as seen in the pics. If so, doesn't that indicate that the in line breakers need to be looked at to see why one or both didn't open?

Edit: Ok. I didn't see Maine' s explanation above. So the resistance of the wire changes due to deterioration and it becomes less than the installed capacity. Makes sense. Now the question is how did that happen when the heater was in a nice dry cozy location, as is mine in the settee?

Maine Sail · Jul 10, 2015

Rick486 said:
This is what bothers me about this incident. Don't we all have the 20 amp isolation breaker in line with the shore power plug? Then we have the breaker on the AC panel in the boat which is said to be 15 A? As Gunni said above, it would seem that the black wire saw more than 15 A to melt the insulation as seen in the pics. If so, doesn't that indicate that the in line breakers need to be looked at to see why one or both didn't open?

NO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!:cussing:

YOU DO NOT NEED MORE THAN 15A TO MELT THE INSULATION!!!!!

You can melt the insulation at substantially less than the breakers rating if you have a poor termination, undersized wire, fractured strands, a loose connection or corrosion that is causing HIGH RESISTANCE.....

Circuit breakers breakers trip on OVER CURRENT they do not trip on HIGH RESISTANCE so long as the current remains below their trip point, and 9 times out of 10 it does in a high resistance situation.

High resistance enough to melt a Class T Fuse block (improper lug stacking) no fuse blow because current remained well below the trip rating.....

These two wires were physically melted together due to high resistance in the wire nut. They were fused at well below the wires maximum ampacity yet no fuse blow.

The 15A breaker never blew in this high resistance situation PLEASE DO NOT USE PLUG IN INVERTERS!!!:

This knuckllehead thought it was okay to crimp solid conductor wire. High resistance, no breaker ever tripped.

Another case of high resistance with a fuse installed at well below the wires max ampacity that never blew.

Another case of high resistance with no fuse or breaker trip (Scotch-Locs have no place being on a boat):

Once again high resistance and no breaker trip because current was well below trip level (42A on a 50A service when this happened). This plug/plastic was at 389 degrees when I pulled it from the socket, in February!

walt · Jul 10, 2015

Regarding the last picture of the plug, it "seems" that usually only one of the terminals is burned up. So a new thing to wonder.. for 110 VAC power cords, is it also usually the HOT plug (ie, black wire) that burns up? Even though the currents are the same on the black and white, the white wire has no voltage potential on it with respect to ground or earth or water or air... All the voltage potential is on the black wire (with respect to the air, ground, water) and maybe that causes it to corrode faster..

Note to clarify a little.. the black and white wires have 110 VAC voltage difference or potenital with respect to each other.. but the white wire is always near ground potential and if fact is usually connected to ground potential back at the source.

I am not at all suggesting this is true.. just wondering if there is correlation with the hot wire on 110 systems in general usually being involved in burns.

It’s also somewhat odd that the air conditioner case also looks like it was the black wire that mainly was involved in burning up. Even though normally the black and the white wires carry equal current (for 110 VAC in the US), the white wire is normally always very close to the earth potential - very close to the green wire potential. It is the black wire that has the voltage on it with respect to the earth potential. Try measuring this at a 110 VAC socket (carefully) with an AC volt meter from green to white (measures near zero) and green to black (measures 110 VAC). Maybe because the black wire has a potential on it with respect to earth potential, it and its connections are more susceptible to corrosion just from being in that marine environment - but that is a complete speculation on my part..

ramblinrod · Jul 10, 2015

Here is the reason why resistance is often the culprit.

P = I^2 x R, where P = Power in Watts, I - Current in Amps, and R = Resistance in Ohms.

Example 1:

A connection in a shore power circuit having 25 Amps and 0.1 ohms = 5 Watts

Example 2:

The same shore power circuit having a connection at 25 Amps and 10 ohms = 500 Watts

As we can see, the power (Watts) increases proportionally with resistance (Ohms).

So what are the power rating units of a heating element? (Watts of course.)

I high resistance point in any circuit, effectively makes a heating element.

Maine Sail · Jul 10, 2015

walt said:
Regarding the last picture of the plug, it "seems" that usually only one of the terminals is burned up. So a new thing to wonder.. for 110 VAC power cords, is it also usually the HOT plug (ie, black wire) that burns up? Even though the currents are the same on the black and white, the white wire has no voltage potential on it with respect to ground or earth or water or air... All the voltage potential is on the black wire (with respect to the air, ground, water) and maybe that causes it to corrode faster..

Note to clarify a little.. the black and white wires have 110 VAC voltage difference or potenital with respect to each other.. but the white wire is always near ground potential and if fact is usually connected to ground potential back at the source.

I am not at all suggesting this is true.. just wondering if there is correlation with the hot wire on 110 systems in general usually being involved in burns.

It is not always the Hot I see equally as many Neutrals burned up. It just happens to be which ever terminal is creating the resistance. Remember both white and black are carrying the same current with the appliance running..

mz4wheeler · Jul 10, 2015

As I look at these photographs again, not focusing on the wires but the whole environment, I see evidence of salt water corrosion all over the place. The edges of the terminal box are rusted, the input/output water pipe connectors, corroded.

The whole inside of the terminal box was also corroded.

Also, the last photograph: If you look at the cardboard, the primary source of heat was centered close to the element (the cardboard burn has a circular pattern)... The black wire.

My conclusion:
The black STRANDED wire (bad on boats!!) corroded to the point where it could no longer support the current passing through it (highER resistance, not HIGH resistance), which turned it into an element itself. Individual strands burned, and as each strand burned it further weakened the entire wire, causing a chain reaction of failed strands. It caught fire internally, but was quickly snuffed out because the catastrophic failure of the wire ONLY lasted for a couple of seconds.

None of this would have tripped the breaker because the current would have never exceeded 15AMPs. You can easily fry any small wire with 15AMPs.

Symptoms: The heater itself (prior) MUST have had lousy heating as the resistance of the black wire slowly increased over the years. As it slowly corroded, the wire would have got hotter and hotter, slowly diminishing the effectiveness of the heater over time.

Cause: The manufacturer used STRANDED wire in a marine environment, and not SOLID core wire, coupled with a corrosive environment. Period!!!

This *IS* a manufacturer defect!!! Yes, you *DO* deserve a free replacement.

I recently replaced my water heater (Atwood), and noticed the wires internally were STIFF, SOLID core wires (good).

Ken Cross · Jul 10, 2015

Please post again when they get back to you

This one is an interesting one. Particularly seeing 2 hot areas in series.

Please post whatever you learn when they get back to you. There are probably lots of us with the same installation.

Ken

Maine Sail · Jul 10, 2015

mz4wheeler said:
As I look at these photographs again, not focusing on the wires but the whole environment, I see evidence of salt water corrosion all over the place. The edges of the terminal box are rusted, the input/output water pipe connectors, corroded.

The whole inside of the terminal box was also corroded.

Also, the last photograph: If you look at the cardboard, the primary source of heat was centered close to the element (the cardboard burn has a circular pattern)... The black wire.

My conclusion:
The black STRANDED wire (bad on boats!!) corroded to the point where it could no longer support the current passing through it (highER resistance, not HIGH resistance), which turned it into an element itself. Individual strands burned, and as each strand burned it further weakened the entire wire, causing a chain reaction of failed strands. It caught fire internally, but was quickly snuffed out because the catastrophic failure of the wire ONLY lasted for a couple of seconds.

None of this would have tripped the breaker because the current would have never exceeded 15AMPs. You can easily fry any small wire with 15AMPs.

Symptoms: The heater itself (prior) MUST have had lousy heating as the resistance of the black wire slowly increased over the years. As it slowly corroded, the wire would have got hotter and hotter, slowly diminishing the effectiveness of the heater over time.

Cause: The manufacturer used STRANDED wire in a marine environment, and not SOLID core wire, coupled with a corrosive environment. Period!!!

This *IS* a manufacturer defect!!! Yes, you *DO* deserve a free replacement.

I recently replaced my water heater (Atwood), and noticed the wires internally were STIFF, SOLID core wires (good).

This post is preciscely backwards/incorrect. Solid conductor wire is disallowed under the ABYC, NMMA & Canada boating standards and has been since the standards have been around. Type 3 stranding (extra fine stranding) is what is called for on boats. Sadly the Atwood is the one not built to meet marine safety standards....

a cautionary note on Seaward water heaters

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