Is 440V a real thing?

I recently worked on the front-end of a project where the Nominal LV potential was described a s 440Vac 3P3W 60hz. At first I assumed that the 440V was the Utilization Voltage (ie based on a Nominal Voltage of 480Vac). I was informed that I was incorrect, and the Nominal Voltage is in fact 440V.
My Question is: Is this correct? (ie has anyone ever heard of a 440Vac system)?


btw The application here is for a VLGC (Very Large Gas Carrier) type of ship (ie a marine environment)

I bet you’ll find, if you dig for it, that 440V is common nominal voltage in the country where the owner of the ship resides, or the country where the engineering contractor resides, or the country they are going to buy their electrical components and instruments, or one of the countries where the ship will shuttle back and forth (maybe where they prefer to dry dock it if needed). I’ve seen 380V (Asia but 50 Hz) to 480. You MUST know this for each locale you work/design for.

Howdy LMan,
I realize what you are saying, but in my +40years of working around the world I have never encountered a 440Vac (nominal) system. I have seen 380Vac, 400Vac, 415Vac systems at 50hz and 480Vac, 600Vac & 690Vac systems at 60hz, but never come across a 440Vac 60hz system. I was wondering if this is perculiar to the marine industry, and not necessarily to any particular country?

I’ve seen it on lists of national voltages for some Latin American countries, but never encountered it ‘in the wild’ myself.


440 Volts was at one time a standard North American voltage.
The standard voltages were multiples of 110 Volts. 110 Volts, 220 Volts 440 Volts and 550 Volts (in Canada).
This is the why 240 Volt systems may sometimes be referred to as 220 Volts.
In the late 40s and into the 60s there was a move to raise the standard voltage to multiples of 150 Volts. There are some vestiges of this in the CEC.
In the late 40s the life of a distribution transformer was about 20 or so years.
The plan was to raise the voltage 1/2 Volt a year until it topped out at 150 Volts.
Old timers will remember seeing appliances rated at 112 Volts for about 5 years.
Then there was 5 years when appliances were rated at 115 Volts.
Then 117 Volts was the standard for another 5 years.
At the end of 20 years, there had been advances in the industry.
Distribution transformers had much longer lives.
Over-voltage P.U. tolerances on transformers and motors had become less.
Distribution voltages had risen from 2400 Volts to 4160 Volts and higher giving much better distribution system regulation.
The voltage increase terminated at multiples of 120 Volts.
The ship may have been a very old ship.
The engineer/designer may have been in his prime in the 440 Volt days. It is easy to set the voltage down or up on a shipboard system.
Going the other way, I have seen several shipboard installations that were based on 120/208 Volt systems where the voltage had been jacked up to 220/127 Volts or 240/139 Volts.
Or there may be another reason for a 440 Volt system.
Do you have any idea which countries the ship called at? That may have been a factor to utilize shore power.

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By the way Groovy Guy, I started a decade or so before you. At that time 480 Volts was the standard but I did work in a few very old mills that were 440 Volts delta.
Most of the old electricians when I was young had worked 440 Volts delta.
There were a few tricks to working ungrounded delta systems.

Hi Bill,
The ships in question are relatively new (ie <10 years old). As far as I know these ships generate all of their own power (ie approx. 10MVA), and historically have not had shore power connections. I also understand that these ships have typically been built in Korea or Europe.
in my opinion a 440V (nominal) power supply, for new applications, is strange indeed.


ps I will update this post if I discover any additional information,

Having worked in shipping industry for 30yrs. I’ve only ever come two or three ships that DID not have a 440v 60hz system. Found a few 415v 50hz ships but they were very few and far between. It is standard for shipping as far as I know.

Shore power (or cold ironing as it is known) is available in some ports for 440v 60hz. Typically all navy bases have it, and few other places were ships will stay tied up alongside for periods of time (typically big cruise liners now are HV at 6.6kv or 11kv 60hz, so they cold iron at HV and the 440v 60hz is derived from onboard HV network)

Thanx for your input Jimmy.
I guess that explains where the 440V (Nominal) 60 hz ratings came from (ie the USN).
So to close this topic off, what is the utilization voltage for a 440V system (ie 420V)?