westom

On 8/9/2022 at 9:41 PM, rudeney said:

They are the same thing.  A short circuit is just an infinite amount of overload (i.e. divide by zero)

An overload can be 19 amps on a power strip.  Overload is by many appliances doing what they were designed for. 

A short circuit is a massive current limited only by the conductors that connect a short to a generator.  Those same wires, that may be overloaded by 19 amps, can also be conducting well over 100 amps during a short circuit.  19 amps clearly is not a short circuit,  

Two completely different anomalies.

An overload and a short circuit are both excessive currents.  With different parameters.  Another example of why honesty must include perspective - numbers.

Only the least educated make declarations without saying why, without any citation, and without numbers.  You make that glaring mistake constantly.

Your statement is a soundbite.  A tweet - less than 140 characters.  Another fact that indicates a lie.  

Please learn how to know something long before posting emotions.

On 8/10/2022 at 3:56 PM, chengkp75 said:

Actually, this is not correct, either.  RCI does not allow any extension cords, or are you going to debate that a power strip is not an extension cord?

Extension cord is clearly not a power strip.  Extension cords are only for temporary service.  Relocatable power taps (also known as power strips) do not have fire code restriction.  Because they are completely different.

Some jurisdictions define 'temporary' for an extension cord as 30 days.  Relocatable power taps are listed for safe use in the National Electrical code.

And then an obvious difference.  Extension cord does not even have a circuit breaker or fuse.  Safest power strips always have that 15 amp circuit breaker.

Please learn basic facts before making conclusions or accusations.  You have but again made a statement based only in your feelings.  By not first learning facts, citations, and numbers.  You do this constantly.

3 hours ago, ALWAYS CRUZIN said:

There are powef strips that are nothing more than a very short (1' or less) extension cord. No breaker nothing. These are acceptable.

Any power strip without protector parts is acceptable to cruise ships.  Since those protector parts are a too common reason for fires - aboard ship or in a house.

Informed consumers also want that 15 amp circuit breaker for increased (sufficient) safety.  Considered so necessary that most all power strips (even those with protector parts) come with that circuit breaker (or fuse).

As stated multiple times, a cruise ship does not demand that 15 amp breaker.  But will confiscate what seriously increases threats to human life - tiny joule protectors.

10 hours ago, chengkp75 said:

I am not talking about a short circuit.  You still don't seem to understand that the "neutral" leg (and there really isn't one in marine electricity) and "ground" are not at the same potential, and that even if the breaker on the power strip cuts the "hot" leg, if there is an insulation failure of an appliance plugged into the power strip, current will still flow from the "neutral" leg to ground, at 60v.

 

When insulation fails  - anywhere after that dual breaker -  hot to neutral, hot to ground, neutral to ground - then a short circuit exists.  Device that must detect and disconnect it is that dual breaker.  In seconds.

That breaker can trip anywhere from a second to two hours.  An overload created by too many appliances would not trip that dual breaker anywhere near fast enough.   And need not.  Because that power strip must have a 15 amp breaker.  That dual breaker can take up to 2 hours to disconnect an overload.  A 15 amp circuit breaker in a power strip disconnects an overload much faster - safer. 

An overload is completely irrelevant to what you keep harping about.  Currents flowing due to an insulation failure are a short circuit.  That 15 amp breaker also might trip.  But a dual breaker back at the panel MUST trip.  No matter where (between breaker and appliance) that short circuit (failed insulation) may be.

Failed insulation between two wires is a short circuit.  Different from another anomaly - an overload.  A 15 amp circuit breaker exists, first and foremost, to disconnect an overload,  How many times will I say this before you finally read it. Read what is written.

A short circuit between any two wires (ie insulation failure) means that dual circuit breaker must trip in a second or less.  But it does not trip fast enough for overloads.

But again - two completely different anomalies: a short circuit and an overload.

22 hours ago, chengkp75 said:

While this is true for land based situations, it is really required for marine installations.  As I've said, that breaker, if it does not interrupt the neutral leg, you can get an amount of current flowing between neutral and ground that is not regulated, except by the upstream, hard wired breaker, whatever its rating is.

 

Unfortunately you have conflated two completely different anomalies.

That 15 amp breaker on a power strip averts overloadiing.  A long and excessive current.

That dual breaker that powers the receptacle trips due to a short (ie milliseconds) circuit.  A current that well exceeds 60 amps (on a 15  or 20 amp circuit) for a very short time.  Two completely different anomalies.

That 15 amp breaker in a power strip is not for short circuits.  It exists to avert overloading.  Short circuits are cut off by that dual circuit breaker.

11 hours ago, chengkp75 said:

The safest power strip on a cruise ship is a European 220v power strip, whether plugged into 220v or 110v outlet, with a circuit breaker that interrupts both legs.

Since everyone here wants to argue minutia, then let's get the numbers right.  European standard is 230v (not 220).  North American standard is 120 (not 110).

A circuit breaker that interrupts both legs is nice.  But does nothing to address the reason for that breaker.  Total sum of current to appliances must be less than 15 amps.

11 hours ago, chengkp75 said:

 

 

 

So, which is it?  "A power strip must have a circuit breaker, that we are supposed to learn from reading "NEMA standards", or "NEMA does not require a circuit breaker"?

Like all standards, a solution both meets and usually exceed  standards.  NEMA only defines an absolute minimum.  Does not define other requirement that also exist for human protection.  Is only a minimal requirement.

Why argue about a part that costs $2 retail?  Solution is so cheap as to almost be irrelevant.  And clearly increases protection.  Do you not want that 15 amp circuit breaker to decrease human safety?  Why?  Breaker is a defacto standard.  Why argue or deny something so silly?

NEMA recommends that circuit breaker or fuse BECAUSE it significantly increases human safety.  So it is a defacto standard..  Why is that hard?

Best power strip has a 15 amp circuit breaker, no protector parts, and a UL 1363 listing.  That simple.

7 hours ago, chengkp75 said:

... so the upstream breaker could be a 20 amp breaker, and the cord for the RPT is only rated for 15 amps.

Wires inside walls are grossly oversized by about a factor of four.  That 14 AWG (15 amp) wire was once the standard for 20 amp circuits.    Even a 20 AWG wire could safely conduct 15 amps.  Power cords with 16 AWG wires are safe and sufficient.

Wire thickness is not a serious human safety threat.  Wires typically are not overloaded.  Physical insult is the problem.  And is why Arc Fault breakers were created.

Meanwhile safest power strip on a cruise ship has a 15 amp circuit breaker, no protector parts, and a UL 1363 listing.  Or something equivalent.

Accurately noted is why a 20 amp circuit breaker is more than sufficient for 15 amp receptacles.  Those numbers say little about how electricity works.  Those numbers are simplified for the benefit of layman.  So that 'decision making' is easier.

More than 15 amps drawn continuously from a NEMA 5-15 receptacle is a human safety problem.  Power eight 100 watt (0.8 amp) incandescent bulbs from that same 15 amp receptacle.  More than 60 amps are initially conducted.  No problem.  Even a 15 amp breaker does not trip.  Because those 60 plus amps are not a human safety threat.

We simply do not tell consumers everything.

Called 15 amps to make it layman simple.   Same number also says that 'more than 60 amps' is also safe.

NEMA does not 'require' a fuse or circuit breaker. Electrical code is not intended to even discuss such products - not its purpose.  But that circuit breaker is strongly recommended.  Most power strips (with and without  protector parts) have them.  An example of why a regulation was not required when an industry implements an effective solution on its own.

That does not mean all power strips have that essential 15 amp circuit breaker.

UL 1363 (or something equivalent) is also essential for human safety.  Hospitals require it.  Informed consumers also want it.  UL 1449 (something completely different) means a power strip has protector parts that have a nasty habit of creating fires.

NEMA and electrical codes are not all requirements.  Those are only minimal requirements. Big difference.

12 hours ago, chengkp75 said:

Even a power strip with a "circuit breaker" only opens the "hot" leg, which does not fully address the problem of overloading due to the neutral on the ship not being at the same voltage as the ground, ...

That human safety feature (one plug to one receptacle) is compromised when multiple plugs are powered by one receptacle. Does not change the fact that power strips must have a 15 amp circuit breaker.

10 hours ago, rudeney said:

 

What rules are you quoting?  is this a maritime electrical code?  

Read NEMA standards.

4 hours ago, ATSEAMYLIFE said:

Ok so you are saying the devices that plug directly into the outlet with multiple USB slots are fine?

All USB ports (from the very first design from Intel) feature a current limiter.  That means a typical USB port will never consume more than 0.21 amps.  Well below a 15 amp limit.

Never matters what one did.  Otherwise we can all run stop signs.  Since I just ran 10 and never killed anyone.

What always matters are facts that predict what is 'safe' and what is 'potentially harmful'.

0.21 amps is not overloading - not a threat.

19 hours ago, rudeney said:

 

I'm not sure I understand what you are saying here.  If an electrical outlet is only rated for 15amps, then there better be a circuit breaker somewhere between it and it's feed line also rated at 15 amps.  

Go back and reread. First point:  Only plug that can mate to that receptacle will always consume less than 15 amps.  

  "Any one plug that can mate to it will never draw more than 15 amps."

Second point.  Any device that connects multiple plugs to one receptacle must have a 15 amp circuit breaker. 

   "So a power strip must have a 15 amp circuit breaker."

Apparently this is new. One does not even begin to grasp something new until a third reread. Even numbers are not seen until a second reading.  Please go back and reread it.

On 8/4/2022 at 8:56 AM, slyster said:

Now, i'm just curious LOL!

Appreciate  both problems.  First, that receptacle is only rated for 15 amps.  Any one plug that can mate to it will never draw more than 15 amps.  But a power strip means more than one plug powered by that receptacle.  A human safety feature compromised.

So a power strip must have a 15 amp circuit breaker.

Second issue.  Protector parts in a power strip are so tiny (Type 3) that, in a home, it must be more than 30 feet from a main breaker box and earth ground.  So that it does not try to do much protection.  Otherwise its tiny joules can [do this](http://www.esdjournal.com/techpapr/Pharr/INVESTIGATING SURGE SUPPRESSOR FIRES.doc).

Safest power strip has a 15 amp circuit breaker, no protector parts, and a UL 1363 listing.  Cruise ships take those two fire threats far more seriously. 

Second one might have had a UL Listing.  First one did not.

8 hours ago, bstel said:

15A outlet --> 14 gauge wire --> 20A outlet = Bad

15A outlet --> 12 gauge wire --> 20A outlet = Bad

20A outlet --> 14 gauge wire --> 15A outlet = OK

20A outlet --> 12 gauge wire --> 15A outlet = OK

20A outlet --> 12 gauge wire --> 20A outlet = GOOD

15A outlet --> 14 gauge wire --> 15A outlet = GOOD

Please learn what any electrician would know.  This  is a NEMA 5-15 receptacle.  It is the most common receptacle found in homes.  Connected to a 20 amp breaker.  If 'Bad', then all new homes are bad.

14 AWG was once the standard and safe wire for all 20 amp circuits.  12 AWG wire was more recently a standard for 20 amp circuits.  Even 18 AWG wire can safely conduct 20 amps.  But we use 12 AWG wire - oversized - for other electrical reasons.  Not because anything is 'Bad'.  12 AWG is better - for other reasons..

If NEMA 5-15 receptacles were not safe for 20 amp circuits, then NEMA 5-20 plugs must be used.  Those look like this.

Wire to NEMA 5-15 (15 amp) plug is typically 12 AWG - for 20 amp circuits.  Is done because engineers know what is safe and necessary.  Apparently wild speculation did not learn basic electrical concepts that say why code powers NEMA 5-15 (15 amp) receptacles from 20 amp circuit breakers and 12 AWG wire.

NEMA 5-15 receptacles are typically on 15 amp circuit breakers (and 14 AWG wire) when that circuit only powers one receptacle box.  Ie a refrigerator.  Decades ago, all 20 amp circuits safely used 14 AWG wire.   Back then, all 15 and 20 amp circuits used cable that was white.  Yellow for 12 AWG is also new upgrade.

One knows this stuff.  Another does not.

10 hours ago, chengkp75 said:

This is quite true.  But on a ship, you can have 480 volts between neutral and ground, with the higher voltage in the safety ground. 

No higher AC voltage is between two wires.   That 120 volt generator does not put 480 volts on cabin receptacles.  It is a voltage that peaks that resides at or between 120 volts RMS.

If 480 volts between neutral and ground, then 120 volts appliances are potentially damaged.  Safety ground is always a voltage located somewhere between the hot and neutral wires.  So that appliances and electronics are undamaged.  And so that human life is not at risk  No 120 volt appliance is safe when a voltage between that appliance, through a human, to ground is 480 volts (peaking at  675 volts).  Please stop inventing number that cannot exist - if human safety exists.

'Reverse voltage' is called 'reverse polarity'.  Neither wire will be more than 120 volts relevant to safety ground.  On ships, that number is typically 60 volts.  Meaning protectors should be even safer.

Protectors fail due to tiny joules.  Not due to a mythical 'reverse voltage'.

If doing this stuff as an engineer, then you know why electronics are so robust.  First it filters transients on AC mains.  Then convert 60 Hz and transients to a DC voltage.  Then filters again.  Then converts that to radio frequency spikes that exceed 300 volts.  Now 'dirtiest' power is inside electronics.

No problem.  Galvanic isolation, regulators, and more filters convert that 'dirtiest' power into DC voltages that do not vary even 0.2 volts.  Best protection at electronics is already inside electronics.  Numbers say so.  Only if one learns basic electrical and electronics concepts rather than believe hearsay and myths.

Type 3 protectors (you did not know what a Type 3 protector is) are a potential fire threat.  Cruise ships take that fire threat (demonstrated by examples with numbers that say why) far more seriously.

Surges do not use up a semiconductor's life.  A surge blows through a transistor's P-N junction - doing damage.  Or it is safely consumed as electricity.  This "use up some of the life" myth is a classic example of junk science reasoning.  "I feel it is true.  So it must be true".  Show me the engineering paper that describes "use up".  I have yet to see it in 50 years of datasheets and application notes doing electronics design.

All appliances and all protectors are designed for 0 volts between neutral and safety ground.  And for 160 volts between neutral and safety ground.  On a ship, that voltage can be above zero and below 120 volts - constantly.  Never 480 volts.

Protectors are a fire threat due to near zero joules.  No way around that specification number.  Cruise ships take that fire threat seriously.

Obviously many urban myths about ship board wiring are promoted.  Without a basic grasp of what appliances and protectors can and cannot withstand.  Even a rumored "reverse voltage" is actually called "reverse polarity".

Warning to all.  Technical lies are rampant.  Promoted by people who do not first learn numbers.  That 480 volt number is a real doozy.

1 hour ago, chengkp75 said:

, and there are a whole lot of dryers rated higher than this. 

So it is not UL listed.  UL is a safety standard.  Some extension cords are also not UL listed - but are still sold.  Even two prong to three prong adaptors are sold - but have no safety listing.  Because it is sold always means it is safe?

Using your reasoning, reverse polarity in home wiring (120 volt difference between neutral and safety ground) was also causing protector fires.

2 hours ago, chengkp75 said:

Thanks for the reminder of what AC means.  Reverse voltage happens when the neutral and earth ground are not at the same potential (voltage).  On land, this does not happen, since the neutral and earth ground are connected together at the breaker box.  

And again, neutral and safety ground are only suppose to be less than a few volts different.  But that does not always exist.  So protectors are designed to with a protector part between neutral and ground that has a 330 volt let-through voltage.  As stated before and repeated again.  All protector parts in a 120 volt surge protector do nothing until voltage between any two wires is above 330 volts.

For same reasons, all appliances are also designed to not be damaged by reverse polarity (what you call reverse voltage).

How much difference between neutral and safety ground on a ship?  60 volts?  No problem.  All appliances are also designed so that this reverse polarity (120 volts) does not cause damage or threaten human life.

Reverse polarity does not and must not harm anything found in a house - appliance or protector. Meaning lesser voltages on a ship also cause no damage.

Again, plug-in (Type 3) protectors must be far away from earth ground even in homes.  Because tiny transients, too small to overwhelm superior protection inside appliances, can catastrophically damage that high profit, tiny joule, plug-in protector.  In rare cases, a surge too tiny to damage any appliance has also  done this .   Cruise ships take this threat far more seriously.

APC recently admitted some 15 million protectors must be removed due to at least 700 potential house fires that they knew about.  That last example was an APC protector that was not on their recall list.  You would have that on a ship?  Recall mentioned  here .  Reason for this problem?  Tiny joules.  Read specification numbers.

8 hours ago, chengkp75 said:

So, I'm confused.  If a 15 amp outlet can only handle one plug in it, regardless of how much power the appliance draws, how is it that a 5 or 6 outlet power strip protected by a 15 amp circuit breaker can handle more than one plug on the circuit.  

15 amp wall receptacles are typically connected to 20 amp circuit breakers.  Safety is provided because any one plug (that will mate) can only be connected to an appliance that typically consumes less than 13 amps.

More electrical concepts apply.  But that is the executive summary.

8 hours ago, chengkp75 said:

No, but as I said, lack of a safety ground means there cannot be surge protection.

Safety ground does nothing to make a protector effective.  Only earth ground does that.  Plug-in protectors are Type 3 .  Must be more than 30 feet from a main breaker box and earth ground so that it does not do much protection.  So that fire is less likely.

Protectors do same with or without a safety ground.  But disinformation promoters know how to create urban myths.  Just forget to include an adjective that must always precede the word "ground".

Problem is that tiny surges (too small to damage appliances) can sometimes cause a plug-in protector fire.  As Lizzie saw.

8 hours ago, chengkp75 said:

Actually, they're not.  The danger of surge protection onboard ships is due to reverse voltage, which, even at low voltages and low energy levels, can cause failure of the MOV components in the surge protector, starting thermal runaway and fire. 

What reverse voltage?  AC electricity is constantly reversing 50 to 60 times every minute.   Protector cicuits look (perform) exactly same even when hot and neutral are reversed.  The expression "reverse voltage: demonstrates  how to promote disinformation.  No facts or numbers define this mythical 'reverse voltage'.  So it gets automatically believed.

Protector parts (all three) between neutral, safety ground, and hot wire have a let-through voltage of 330 volts.  The part between hot and neutral is the same part between neutral and safety ground.  And between hot and safety ground. What voltage between those three wires exceeds 330 volts?  None.

Reverse voltage myth exposed by numbers.

Problem is created by tiny transients, easily made irrelevant by protection inside electronics, that can spike voltages across those protectors parts at greater than 330 volts.

Destructive anomaly is quite rare.  Made irrelevant by superior protection already inside all appliances.  And can be a problem for least robust protector parts inside plug-in protectors.

The MOVs in surge protectors are designed to experience higher voltage and not fail.  Let-through voltage is 330 volts.  To promote hearsay and urban myths to consumers who ignore numbers, advertising lies are subjective.  No numbers.  Do not discuss critical facts such as its tiny joules and let-through voltage.

A surge, that only inflamed Lizzie's protector, did not damage other household appliances.  Same also happened here.   Fortunately the fire busted an aquarium putting out that fire.

Protection inside electronics is superior to what is inside a plug-in protector.  A $3 power strip with five cent protector parts. When it fails (catastrophically) on a surge too tiny to damage anything else, then wild speculation says, "My protector sacrificed itself to save my appliance."

Undersizing a protector increases sales and profits.

Reality.  Fortunately surges are quite rare.  And still cruise ships take that threat quite seriously.

Protection is same with or without a safety ground.  Disinformation forgets to mention which ground does protection.  Earth ground.  Plug-in protectors must be away from earth ground to not do much protection - to not create a fire.  Only Type 1 and Type 2 protectors are robust enough to make a connection to earth ground - to do effective protection.  But those cannot be connected aboard ship.

UL 1363 means it has no protector parts.  Safety ground (third prong) says nothing about surge protector parts.  Since safety ground does nothing to make any protector effective.

UL 1449 means it has protector parts.

Protectors strips are a fire threat for the same reason they create so many fires inside homes.  One need only read specification numbers to appreciate why.  Even electronics will safely  convert thousands joules surges into low DC voltages that safety power semiconductors.  Thousands joules can also do this:

"Lizzie Steinmetz, 5, was getting ready for bed with her little brother when she heard a strange noise. "It was like a buzzing noise sound," Lizzie said. She said she saw flames shooting up from a surge protector sitting on top of her dresser."

Problem is created by five cent protector parts added to a $3 power strip to sell for $25 or $80.  It is a profit center; not effective protection.

Protector parts have a thermal fuse to disconnect only protector parts during a surge.  While leaving that surge fully connected to appliances.  No problem.  Appliances are more robust.

But sometimes that thermal fuse does not disconnect protector parts fast enough.  Fire can result.

Those protectors are just as dangerous in a home.  But cruise ships take that fire threat far more seriously.  Why is this acceptable behavior?  Because so many are educated by advertising and other disinformation.  Anyone can read what is relevant.  How many joules will it 'block' or 'absorb'?

That third 'safety ground' prong exists to protect human life - not appliances.

Extension cords:  shape of that wall receptacle means any one plug powered by it is safe.  When one receptacle is powering more than one plug, then a fire threat exists.  That human safety feature is compromised when more than one plug is powered by one wall receptacle.

That is also why safe power strips (without protector parts) must have a 15 amp circuit breaker.  So that too many plugs do not demand more than 15 amps from one wall receptacle.

Obviously that extension cord must also have a UL listing (or something equivalent).

Fires created by extension cords in homes were NOT typically due to overloading.  Extension cords failed mostly due to physical insult.  Arc fault circuit breakers were created because of how extension cords mostly failed.  Not overloading; physical damage.

14 hours ago, Benthayer Gonbak said:

 

One of our sewing machine stores was teaching that joules matter when trying to protect expensive embroidery machines!  It was the first time I’d seen anyone pointing out that it really mattered!

How many joules did they say matters?  Plug-in protectors (hundreds or thousand joules) are near zero joules - ineffective.  Joules only matter when that associated number is considered.  Effective protection is where hundreds of thousands of joules are harmlessly 'absorbed'.

What is the protector parameter that answers that question?  Ineffective protectors are rated in joule.  Effective 'whole house' protectors are rated in thousands of amps - not joules. Then hundreds of thousands of joules harmlessly dissipate outside and safely in earth.  Both devices called protectors.  The effective one quantified by a different specification number.

How many joules does a UPS claim to absorb?  Hundreds.  Many times less than a tiny joule power strip.  Then they can claim that UPS does 100% protection.  Scams are that easily promoted when one does not always demand the numbers.

A tiny joule number on any plug-in protector indicates a possible (but rare) fire threat. Cruise ships take that threat (created by near zero joules) more seriously.

9 hours ago, SRF said:

They do not protect again lower voltage surges.  And they will only protect against a single surge/spike event.  The second event has NO protection. 

 

Demonstrated is why plug-in protectors cause fires.  Its protector part must never fail catastrophically.  It may only degrade.  Described is a catastrophic failure traceable to a number in its specifications - joules.  What happens when a hundred or thousand joule protector tries to 'block' or  'absorb' hundreds of thousands of joules?

Either a 1 amp thermal fuse disconnects protector parts as fast as possible.  Or, if too slow, then a protector part fails catastrophically - causes a fire.  Meanwhile, that surge remains connected to the appliance (which has better protection internally).

Effective protectors answer this question.  Where do hundreds of thousands of joules harmlessly dissipate?  Those degrade; do not fail catastrophically.

Hundreds or thousand joules?  Electronics routinely convert a surge that tiny into rock stable, low DC voltages to safely power semiconductors.  Why would anyone spend so much money on a protector that is inferior to what is already inside appliances?  How many never read those numbers?  How many joules does it claim to absorb?

Any protector that fails means ineffective protection exists or existed.  Catastrophic failure is why some protectors create fires (in ships or homes).

On 8/3/2017 at 3:29 PM, easyboy said:

I guess the risks are just not appreciated by others as it is more covenient to pack what is used at home where they need surge protection.

 

That protector in a home creates the same fire hazard.   A power strip with a UL 1363 listing has no protector parts - is safe.  One with a UL 1449 is the type that so often results in fires.

Ships simply take the threat far more seriously.  Details provided here