16,000 amp wire?

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Twoskinsoneman

Senior Member
Location
West Virginia, USA NEC: 2020
Occupation
Facility Senior Electrician
Talking to a tech who used to be on subs in the navy. He told me they had "super shore power" cables they would connect to the submarine in the dock. One wire for each of the three phases that would carry 16,000 amps. He said each wire was estimated to be about a 4" diameter (my estimate based on the shape he made with his hands).

Obviously this goes well beyond the 2000 kcmil limit of the code.

Just wondering if there were any navy guys out there that could verify at least the idea of this... 16,000 amps? Custom made 4" dia wires?

I'm leaning toward this being complete bunk but thought I would ask around...
 

kwired

Electron manager
Location
NE Nebraska
Is it possible they were multiple multiconductor cables in one overall covering connected in parallel?

What was the voltage? If medium voltage cables the conductors may be a lot smaller than the insulation.
 

Twoskinsoneman

Senior Member
Location
West Virginia, USA NEC: 2020
Occupation
Facility Senior Electrician
Is it possible they were multiple multiconductor cables in one overall covering connected in parallel?

What was the voltage? If medium voltage cables the conductors may be a lot smaller than the insulation.

No way to know for sure... he says it was a single wire and 480v...
But I guess the voltage doesn't matter with his 16000a claim...
 

kwired

Electron manager
Location
NE Nebraska
It is also my understanding they use 400 hz often in those types of craft. This could require things most of us are not used to seeing. By using 400 hz they are able to use less steel in the winding cores of motors, transformers, generators, etc thus reducing the weight. I know this is common on aircraft for that reason.
 

hurk27

Senior Member
How would you handle a 4" copper cable, even if fine strand?
I think the amperage is bunk, I cant see any loads that a sub would require 16ka for.
I thought we retired all the diesel/electric subs years ago?
 

renosteinke

Senior Member
Location
NE Arkansas
It's not an impossible claim .... When nuclear subs are in port, they actually feed power into the local grid. Each sub can easily provide power to 20,000 homes.

Must be some awesome wire nuts! :D
 

Rockyd

Senior Member
Location
Nevada
Occupation
Retired after 40 years as an electrician.
I call BS. what I know - I was assigned to a Submarine Tender (AS-39) from 1979 to 1982, an here is the skinny from the old world.

To feed a sub next to us, we would feed them four(4) THOF 400's.

Each cable delivered 400 Amps at 480 VAC

Multiply that times four (4)

1600 Amps of AVAILABLE current, at 480VAC.

Now I will admit that the cables work both ways, we had a sub carry us one time when the city of Norfolk, VA. lost power for a few hours to our pier. But subs running whole cities? Na, ain't happening.

Edit to include the fact that the subs run at 60 Hz.
 

kwired

Electron manager
Location
NE Nebraska
Edit to include the fact that the subs run at 60 Hz.

I know nothing about what is on subs, but was just suggesting the possibility. It certainly would not suprise me if they were to run on just about any frequency deemed best for the design.

You would still expect there to be a 60 Hz system for some items, especially for personal items.
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
I would lean toward bunk, or at least not 100% accruate information.

What would a sub do with 16,000 amps anyway? My guess is that too high of a current to directly feed to any loads. Probably even too high for charging all the batteries on a sub.

So the first thing a sub would do with 16000 amps is to step up the voltage and step down the current to a more reasonable level. But why wouldn't you do that before you send the current through a cable to the sub??

1600 amps would be more reasonable, or maybe 16000 Volt-Amps, or even the power equivalent of 16000 amps equivalent at a lower voltage.
 

Besoeker

Senior Member
Location
UK
Talking to a tech who used to be on subs in the navy. He told me they had "super shore power" cables they would connect to the submarine in the dock. One wire for each of the three phases that would carry 16,000 amps. He said each wire was estimated to be about a 4" diameter
We do a fair bit of high current work for systems that are typically tens of kA. Generally, we use copper bus bars and usually in parallel. For 16 kA we'd maybe use four 8" by 0.5" inch bars in parallel. That's a greater cross-sectional area than the one 4" diameter cable.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor

kwired

Electron manager
Location
NE Nebraska
I would lean toward bunk, or at least not 100% accruate information.

What would a sub do with 16,000 amps anyway? My guess is that too high of a current to directly feed to any loads. Probably even too high for charging all the batteries on a sub.

So the first thing a sub would do with 16000 amps is to step up the voltage and step down the current to a more reasonable level. But why wouldn't you do that before you send the current through a cable to the sub??

1600 amps would be more reasonable, or maybe 16000 Volt-Amps, or even the power equivalent of 16000 amps equivalent at a lower voltage.

Do you want to think about what you said here?

You don't supply the sub with 16,000 amps you supply it with conductors with 16,000 ampacity. The sub only draws that much if that amount of load happens to be connected.

You don't take 16,000 amps and step up the voltage, you take 240 volts and step it up to 480 or something like that. But if you take 16000A @ 208 and step it up to 480 you have 8000 amps. If you wanted to reduce size of cable by a considerable amount you need to step it up to something like 12.5 Kv - but then you need transformer on the sub to step it back down and that will waste space for something that is not needed when out at sea.

16000 volt amps is not really that much power I have more back up heat than that in my heat pump.

If it is indeed 16,000 amps @ 480 volt 3 phase then you have 13.3 Meg volt amps capability. Doesn't seem too much out of line to me. This is not a 14 foot fishing boat were talking about here.
 

Twoskinsoneman

Senior Member
Location
West Virginia, USA NEC: 2020
Occupation
Facility Senior Electrician
Do you want to think about what you said here?

You don't supply the sub with 16,000 amps you supply it with conductors with 16,000 ampacity. The sub only draws that much if that amount of load happens to be connected.

You don't take 16,000 amps and step up the voltage, you take 240 volts and step it up to 480 or something like that. But if you take 16000A @ 208 and step it up to 480 you have 8000 amps. If you wanted to reduce size of cable by a considerable amount you need to step it up to something like 12.5 Kv - but then you need transformer on the sub to step it back down and that will waste space for something that is not needed when out at sea.

16000 volt amps is not really that much power I have more back up heat than that in my heat pump.

If it is indeed 16,000 amps @ 480 volt 3 phase then you have 13.3 Meg volt amps capability. Doesn't seem too much out of line to me. This is not a 14 foot fishing boat were talking about here.


this is kinda why I posted to get other opinions. It was a nuclear power submarine. Which I image could generate quite a bit of power. But even if it was 4" wire......16000 amps?
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
Do you want to think about what you said here?.

I have.

You don't supply the sub with 16,000 amps you supply it with conductors with 16,000 ampacity. The sub only draws that much if that amount of load happens to be connected.

You missed the point. There is no point in providing a 16000 amp cable for something that is drawing much less current. For example, why provide a cable like that for something that only drawing 600 amps?

You don't take 16,000 amps and step up the voltage, you take 240 volts and step it up to 480 or something like that. But if you take 16000A @ 208 and step it up to 480 you have 8000 amps. If you wanted to reduce size of cable by a considerable amount you need to step it up to something like 12.5 Kv - but then you need transformer on the sub to step it back down and that will waste space for something that is not needed when out at sea.

Again, either I didn't make my point clear enough, or you missed it. Say the cables really carry 16,000 amps. What are they going to terminate in? A switchboard rated 16,000 amps?? What would be the point? The weight and space of all the bussing and cabling and structure would have to be more than a transformer.

The voltages and currents on a sub are going to be designed to keep the equipment small and lightweight. I don't think 16000 amps is going to fit that bill.

16000 volt amps is not really that much power I have more back up heat than that in my heat pump.

If it is indeed 16,000 amps @ 480 volt 3 phase then you have 13.3 Meg volt amps capability. Doesn't seem too much out of line to me. This is not a 14 foot fishing boat were talking about here.

I'll agree, 16000 VA's is way low, I was just trying to throw out some ways the person telling the story might of misinterperted how much current the cables really carry.

There is just no way a 4" cable is going to carry more than about 1600 amps. No way to get 10x that number in a single conductor.

There are good reasons we rarely see equipment rated at more than about 5000 amps. Those reasons aren't going to be much different for a submarine. In fact, space and weight constraints would probably dictate keeping the voltages higher and the currents lower than for a typical building.
 

Strife

Senior Member
16,000A it's around 13MW. That's a small power plant. I built a 1000 apt condo with a lot of commercial space and was less than that. I did some research on nuclear subs and their own power plants are around 30-40MW. But I'm sure most of that is for the engines. And a 4" diameter wire would still not be good enough for 16000A.
As far as the comment of sending higher voltage to the sub and stepping down (so the wires would be smaller), do you realize the weight added by those transformers?

Talking to a tech who used to be on subs in the navy. He told me they had "super shore power" cables they would connect to the submarine in the dock. One wire for each of the three phases that would carry 16,000 amps. He said each wire was estimated to be about a 4" diameter (my estimate based on the shape he made with his hands).

Obviously this goes well beyond the 2000 kcmil limit of the code.

Just wondering if there were any navy guys out there that could verify at least the idea of this... 16,000 amps? Custom made 4" dia wires?

I'm leaning toward this being complete bunk but thought I would ask around...
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
We do a fair bit of high current work for systems that are typically tens of kA. Generally, we use copper bus bars and usually in parallel. For 16 kA we'd maybe use four 8" by 0.5" inch bars in parallel. That's a greater cross-sectional area than the one 4" diameter cable.

Not only is it a greater cross sectional area, bus bars can have several advantages in current carrying capacity over "cables". Like:

1. A wire has a lower temperature limit than a bus bar, due to the temp. rating of the insulating covering. You can let bare copper get a lot hotter than a thermoplastic wire covering.
2. Bus bars don't have to be completly covered by an insulator, so the heat can dissipate faster.
3. Bus bars are flat, so again, they give off heat a lot better.
4. For large conductors, not much current flows in the center of the wire. This makes ever increasing wire sizes produce smaller and smaller increases in ampacity. Flat bus bars have a much more even current carrying profile. For a 2x increase in the area of a bus bar, you might even get a 2x increase in amapacity.

But for wires, looking at 310.16, as you go from 4/0 to 2000 KCM (probably about a 10x increase in the amount of copper), the ampacity only goes from 260 amps up to 750 amps. (Lets assume they have nice high temp cables and terminations). You don't even get 3x the ampacity for 10x the amount of copper.

There is just no way to get 16000 amps in a cable without doing something really bizzare, like maybe using superconductors.
 

jeremysterling

Senior Member
Location
Austin, TX
I call BS. what I know - I was assigned to a Submarine Tender (AS-39) from 1979 to 1982, an here is the skinny from the old world.

To feed a sub next to us, we would feed them four(4) THOF 400's.

Each cable delivered 400 Amps at 480 VAC

Multiply that times four (4)

1600 Amps of AVAILABLE current, at 480VAC.

Now I will admit that the cables work both ways, we had a sub carry us one time when the city of Norfolk, VA. lost power for a few hours to our pier. But subs running whole cities? Na, ain't happening.

Edit to include the fact that the subs run at 60 Hz.

Thanks Rocky, for the memories. I remember being EM3, standing "turtle-back watch" through the night, sitting on those shore power cables, reporting if they were dipping to low near the water.

We would grease the terminal ends before connecting them to our sub.

One night I was SEO (Shutdown Electrical Operator) in maneuvering. We were Tango 3 on the Simon Lake sub-tender. Our shore power was good, so I was drinking bug juice and trying to stay awake.

Another boat was outboard of us (Tango 5). Tango 5 kept calling the Simon Lake complaining every 15 minutes that the shore power was not good. After about two hours of this, I hear on the phones, " Simon Lake, Tango 5...Our shore power is still...TANGO FIVE LOSS OF SHORE POWER!!!"

I think the electrician on the Simon Lake got fed up with the guy's complaints and opened up the shore power breaker figuring Tango 5 would be happier running his diesel generator!

That was pretty funny, because shore power is way preferable to the noise and smell of the diesel.:grin:
 
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