Typography rules for units of measurements

Azzu

Senior Member
French - France
Hello,

I was not very sure if I could post this thread here: I have doubts on the right typography to be used with the units of measurement.

Is there a space between a number and a unit of measure? For example: is it "24V power supply" or "24 V power supply"?
Also, when it is "24 volt direct current", is it "24 V DC or 24 VDC? Or something else?

Many thanks in advance,
 
  • Istarion

    Senior Member
    British English
    Hi Azzu,
    There's no space between the number and the unit. In your example it would be "24V DC".
    Edit: see below.
    -I
     
    Last edited:

    entangledbank

    Senior Member
    English - South-East England
    No, there should be a space: it is 24 V, not 24V. This is an international standard for all metric units. Appliances often disregard this and write things like 24V, but this is one case where we can clearly say it's wrong. The unit is not attached to anything else either, so it's 24 V DC.
     

    Istarion

    Senior Member
    British English
    My apologies, I looked it up and apparently you are right, entangledbank. My mistake for replying without checking my facts.
    It's true that I most often see them written without a space, though, I think.
    -I
     

    sdgraham

    Senior Member
    USA English
    Can you cite the "international standard?"

    I note that Google returns 54.8 million hits for "12V" :confused:

    (And my Subaru Outback owners manual specifies "12V DC" for the auxiliary power outlet :))
     
    Last edited:

    RM1(SS)

    Senior Member
    English - US (Midwest)
    Interesting. I was taught to use, for example, "12V" to mean "12-volt," and "12 V" to mean "12 volts."

    I see no reason to change....
     

    sdgraham

    Senior Member
    USA English
    Interesting discussion"and I'm sure many will get a charge out of it.

    Apparently the space is the gospel according to an IEEE document. (260.1) where they prescribe spaces between numeric values and the abbreviations for whatever is being counted, be volts or anything else.

    "The Institute of Electrical and Electronics Engineers (IEEE, read I-Triple-E) is a professional association headquartered in New York City that is dedicated to advancing technological innovation and excellence. It has about 425,000 members in about 160 countries, slightly less than half of whom reside in the United States. (Wiki)



    It makes sense, but as with all other style guides, whether one chooses to follow it or go with popular usage is a personal matter unless otherwise dictated by the employer, teacher or other person in a position to inflict discomfort. The "right" way often flies in the face of common usage such as mentioned in this thread.

    Interestingly, the style book used by virtually all North American newspapers is moot on the volt issue, which likely would fall under the category of "write out the full word."

    Back when I was dealing with emerging standards for international electronic transmission of news and photos, our, i.e. those of us representing international news agencies, private joke was "...the nice thing about 'standards' is that there are so many to choose from." :)
     

    JeanDeSponde

    Senior Member
    France, Français
    This technical document (datasheet for an electronic component) is randomly mixing standards (space, or no space), and is typical of what I can read (and write) everyday.
    As far as I know, non-tech people use a space (because they've been told to) and tech people don't.
    Maybe tech document are written by techies and partially proofread by non-techies...
     
    Top