Power Strip Question

[natalie_healyoursoul]

Is it true that you can't bring a power strip if it has a surge protector? I have seen this over and over on different packing lists, but was hoping that was outdated information. If that is the case, can someone explain why?? I'm sure there's a good reason, but I don't have a clue what it would be.

[MisterOJ2]

Right. If you bring one, it CANNOT have a surge protector. Something about the way those work screws with the ship's electrical system.

Edited July 5, 2019 by MisterOJ2

[natalie_healyoursoul]

Ok thanks! I guess we will buy a new one just for the cruise.

[MisterOJ2]

4 minutes ago, natalie_healyoursoul said:

Ok thanks! I guess we will buy a new one just for the cruise.

 

We use one similar to this when we cruise. 

 

[ShakyBeef]

1 hour ago, natalie_healyoursoul said:

Is it true that you can't bring a power strip if it has a surge protector? I have seen this over and over on different packing lists, but was hoping that was outdated information. If that is the case, can someone explain why?? I'm sure there's a good reason, but I don't have a clue what it would be.

 

 

Here's a thread where it is explained by the experts:

 

 

[Shaded Lady]

51 minutes ago, ShakyBeef said:

 

 

Here's a thread where it is explained by the experts:

 

 

 

Thanks Shaky- I was just digging up Chengkp75's post when you put this up here!!! 

[coevan]

Since all devices come with USB plugs we just use this, although it says "surge protected" it is not. I have checked with Home Depot and my electrician : 

 

https://www.homedepot.com/p/4-ft-6-Outlet-Power-Strip-Surge-Protector-with-45-Angle-Plug-YLPT-90/203353677

[webzila]

Almost everything is USB now. Something like this works great, just bring USB cords
https://www.biglots.com/product/white-4-port-usb-wall-power-strip-charger/p810372477?pos=1:2&Ntt=Usb+charger

Sent from my Pixel 2 XL using Tapatalk

[chengkp75]

17 hours ago, ShakyBeef said:

 

 

Here's a thread where it is explained by the experts:

 

 

That actually was before I really did my homework on surge protectors.  The real danger comes from the fact that the surge protector's semi-conductors are designed to see voltage in one direction, when it is very high in the power leg of the circuit, and low in the ground wire, it will shunt voltage to ground to protect devices.  If, however, as is possible on a ship, a device fails to ground from the 220v circuits in the ship, these semi-conductors can now see a higher voltage in the ground wire than is in the power wire, and this "reverse voltage" can cause these semi-conductors to fail in what is known as "thermal runaway", where even low currents (below what a circuit breaker would trip at) can cause excessive heat in the surge protector, and start a fire.

 

The simple fact to understand is that absolutely none of the ship's electronics (that are way more valuable than your Iphone or laptop), and which are relied on to keep the ship operating and keep you safe, have any type of surge protection at all.  I have been on several ships struck directly by lightning, and none of the ship's electronics were affected in the slightest (say that about your home).  The difference in how ships are grounded compared to land systems, which makes surge protectors dangerous, also makes them completely unnecessary.

[midcarolina]

First..I will be shocked ( pun intended ) if this reply doesnt get deleted. But, the cheap power strip surge protectors are a fire hazard anywhere they are used...And it has nothing to do with grounding. Cheap surge protectors work by using metal oxide varistors to resist power spikes or changes, any time you resist electrical changes you create heat, that heat is the danger.

 

any surge protector has a life span that varies depending on how hard the metal oxide varistors have to work.

A ships power supply can be variable even slight variations cause these MOV's to heat up! As you can imagine heat in a plastic housing is a serious fire hazard! I would not use them in my house.

 

 

[chengkp75]

2 hours ago, midcarolina said:

First..I will be shocked ( pun intended ) if this reply doesnt get deleted. But, the cheap power strip surge protectors are a fire hazard anywhere they are used...And it has nothing to do with grounding. Cheap surge protectors work by using metal oxide varistors to resist power spikes or changes, any time you resist electrical changes you create heat, that heat is the danger.

 

any surge protector has a life span that varies depending on how hard the metal oxide varistors have to work.

A ships power supply can be variable even slight variations cause these MOV's to heat up! As you can imagine heat in a plastic housing is a serious fire hazard! I would not use them in my house.

 

 

That's not my understanding (and I'm not a full EE) of how varistors work.  The varistor works by acting as a switch, not a resistance to voltage or current.  When the voltage reaches a set point, the switch opens and power is shunted, at almost no resistance, from power lead to ground. When the voltage is below the clamping voltage, the resistance of the surge protector is so high, there is a essentially no current flow from power to ground.  Without current flow, there is no heat.  What can cause a surge protector to heat up is that the semi-conductors are not designed to see voltage in that direction, and this can cause the heat.

 

You are correct that MOV surge protectors have a life span, and this is the "joule" rating that is sometimes seen on a surge protector.  Whether this amount of joules of energy is seen in one spike, or in many smaller spikes, the MOV fails open, not closed, and therefore simply stops protecting your device from further spikes.

[LandlockedCruiser01]

5 hours ago, chengkp75 said:

The simple fact to understand is that absolutely none of the ship's electronics (that are way more valuable than your Iphone or laptop), and which are relied on to keep the ship operating and keep you safe, have any type of surge protection at all.  I have been on several ships struck directly by lightning, and none of the ship's electronics were affected in the slightest (say that about your home).  The difference in how ships are grounded compared to land systems, which makes surge protectors dangerous, also makes them completely unnecessary.

I'm not an electrician or an electrical engineer, although I took a college class on electrical systems.  It was an intro class, so I only learned about terrestrial wiring.  How does grounding work on a ship?  Considering how there is no ground to speak of; the ship is on water.  Does the "ground" wire extend outside the hull into the ocean?  Or are there just the hot and the neutral wires, with no ground, working like on land?

Edited July 6, 2019 by LandlockedCruiser01

[chengkp75]

1 hour ago, LandlockedCruiser01 said:

I'm not an electrician or an electrical engineer, although I took a college class on electrical systems.  It was an intro class, so I only learned about terrestrial wiring.  How does grounding work on a ship?  Considering how there is no ground to speak of; the ship is on water.  Does the "ground" wire extend outside the hull into the ocean?  Or are there just the hot and the neutral wires, with no ground, working like on land?

Well, the first assumption is incorrect.  The water works just as fine as a ground as the "ground" does.  It conducts just fine, ask anyone who throws the hair dryer in the bathtub.  So, the ship's hull is grounded to the earth via the ocean.  However, since a ship is made up of various metals, and these metals are in an electrolyte solution (sea water), you have the potential for a battery, just add current.  So, if current flows in the hull of a ship, you risk galvanic corrosion of "less noble" metals, like steel and aluminum, and that is a bad thing.  So, we try not to have any current flow in the "ground" which is the hull.  We do this by not having the neutral wire bonded to the ground wire like it is in your home at the circuit breaker box.  Both the "hot" and "neutral" wires are at voltages above the ground wire (like L-G=60v, N-G=60v, so L-N=120v).  This ground wire is connected to all other ground wires throughout the ship and led back to the neutral point of the "Wye wound" generator (which has zero voltage).  So, any potential ground fault or leakage current will flow in the ground wire back to the generators and not through the ship's hull.  Many people get the idea that a ship is "ungrounded", but it's not, it has a "floating ground", meaning not that the ship is floating, but that the two (or three for three phase power) conducting wires "float" above the ground voltage.

 

 

[LandlockedCruiser01]

28 minutes ago, chengkp75 said:

Well, the first assumption is incorrect.  The water works just as fine as a ground as the "ground" does.  It conducts just fine, ask anyone who throws the hair dryer in the bathtub.  So, the ship's hull is grounded to the earth via the ocean.  However, since a ship is made up of various metals, and these metals are in an electrolyte solution (sea water), you have the potential for a battery, just add current.  So, if current flows in the hull of a ship, you risk galvanic corrosion of "less noble" metals, like steel and aluminum, and that is a bad thing.  So, we try not to have any current flow in the "ground" which is the hull.  We do this by not having the neutral wire bonded to the ground wire like it is in your home at the circuit breaker box.  Both the "hot" and "neutral" wires are at voltages above the ground wire (like L-G=60v, N-G=60v, so L-N=120v).  This ground wire is connected to all other ground wires throughout the ship and led back to the neutral point of the "Wye wound" generator (which has zero voltage).  So, any potential ground fault or leakage current will flow in the ground wire back to the generators and not through the ship's hull.  Many people get the idea that a ship is "ungrounded", but it's not, it has a "floating ground", meaning not that the ship is floating, but that the two (or three for three phase power) conducting wires "float" above the ground voltage.

Wow, good explanation!  I know about galvanic corrosion due to metallic reactivity, and the idea of a Earth-sized battery (the ocean) sounds pretty cool.  But other information was new to me.  Are the three-prong American outlets in cabins connected to the same ground?

 

If your avatar/icon is reflective of real life, thank you for your service. 

[chengkp75]

2 hours ago, LandlockedCruiser01 said:

Wow, good explanation!  I know about galvanic corrosion due to metallic reactivity, and the idea of a Earth-sized battery (the ocean) sounds pretty cool.  But other information was new to me.  Are the three-prong American outlets in cabins connected to the same ground?

 

If your avatar/icon is reflective of real life, thank you for your service. 

Yes, the ground pin in the 110v outlet, as well as the two metal springs in the 220v outlet are connected to the ground system, for safety.

 

While I did a short stint of Naval Reserve duty, I am a civilian merchant mariner, for 45 years.

[kenb]

6 hours ago, chengkp75 said:

That's not my understanding (and I'm not a full EE) of how varistors work.  The varistor works by acting as a switch, not a resistance to voltage or current.  When the voltage reaches a set point, the switch opens and power is shunted, at almost no resistance, from power lead to ground. When the voltage is below the clamping voltage, the resistance of the surge protector is so high, there is a essentially no current flow from power to ground.  Without current flow, there is no heat.  What can cause a surge protector to heat up is that the semi-conductors are not designed to see voltage in that direction, and this can cause the heat.

 

You are correct that MOV surge protectors have a life span, and this is the "joule" rating that is sometimes seen on a surge protector.  Whether this amount of joules of energy is seen in one spike, or in many smaller spikes, the MOV fails open, not closed, and therefore simply stops protecting your device from further spikes.

OK, This has got way over my and most peoples head. Bottom line is DO NOT BRING A POWER STRIP WITH A SURGE PROTECTOR!!

[ALWAYS CRUZIN]

If you happen to have the a Dollar Tree by you for a $1.00 they have this. The cord is about 14 inches long.

Offered by Sunbeam and UL approved as it should be. Rated at 125 volts 13 amps. Take mine with me on every cruise.