Which preposition do I use if I want to say that someone's work place is a power plant? For example:

I work in a power plant.

I work on a power plant.

I work at a power plant.

  • I'm Working On a Building – TaW Feb 2 at 20:50

This is a great question!

The first and third options - "in a power plant" and "at a power plant" - are both correct for this specific example of work, so long as you mean "doing some job inside an existing power plant".

The second option "on the power plant" would mean something different - e.g. that you are an engineer or labourer involved with the construction of a new power plant. For instance:

"I'm a design engineer, and I am working on the power plant == "I am working on the design of the power plant."

However, in other cases, the "on" preposition will be appropriate. The general principle is that:

  • "at" or "in" are generally used when the worksite is indoors (e.g. an office, factory, shop, etc), while
  • "on" is typically used when the worksite is an outdoor structure (and the work is done largely outside).

The following examples illustrate.

Examples where "in" or "at" are (largely) interchangeable

  • "I work in a bank." or "I work at the bank."
  • "I work in a factory." or "I work at a factory."
  • "I work in a grocery store." or "I work at the grocery store."
  • "I work in a power plant." or "I work at a power plant."

Note that in these examples, the "at" preposition will generally be more appropriate where the workplace is a specific workplace (preceded by "the").

Examples where "on" is essential

  • "I work on an oil rig."
  • "I work on a ship."
  • "I work on the rail tracks."

Examples where "on" or "at" are largely interchangeable

  • "I work on a construction site." or "I work at a construction site."
  • "I work on the wharves." or "I work at the wharves."

Examples where "at" is essential

  • "I work at the outdoor vegetable markets."
| improve this answer | |
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    I think "I work in the outdoor vegetable markets." wouldn't sound too unnatural, despite "at" being favourable. But I would add that "at" would be the only appropriate preposition if the worksite isn't a physical place, e.g., "I work at Amazon". But in that case, you could use "for". – Jam Feb 1 at 23:57
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    But 'work on a boat' can mean both simple location and involvement in its construction. A sailor works on (not at or in) a boat. A ship-builder works on a boat (at a boatyard). – Laurence Payne Feb 2 at 18:30
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    Not sure your inside/outside works. 'I work in the fields' – Aequitas Feb 3 at 6:13
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    I think these rules are too specific. This is a decent first pass, but there’s just a few that don’t really fit. I guess as with all of English, it’s complicated. – Tim Feb 3 at 13:00
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    @TechnoCat I think you’ve got the general answer and then it’s a combo of what “sounds” natural and learning from hearing others say it. I certainly couldn’t tell you the rules I use, it’s just “natural”! – Tim Feb 3 at 13:11

All three could be used, but they have slightly different connotations concerning the exact workplace of the worker.

I work in a power plant.

The employee's tasks are inside the power plant. (She may be a janitor, but her work is inside the structure.)

I work on a power plant.

The worker's job is constructing or caring for the power plant itself. (He is probably a civil, electrical, or mechanical engineer.)

I work at a power plant.

The laborer's work is located within the property lines of the premises of the power plant. (She may be outdoor security or landscaper or driver and she never enters the power plant, even though she works near it.)

Additionally, one also might say:

I work for a power plant.

The worker's employer is a company that owns the power plant. (He may be a worker from the previous examples or he may be a researcher or manager or salesman who does all his work off-site.)

| improve this answer | |
  • 1
    This is a good answer for the subtle difference, even in this context, between ‘in’ and ‘at’. – Toby Bartels Feb 2 at 15:38
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    Hmm. I would take issue with the last one. Power plants are equipment owned by utility companies, so the plant isn't the employer. And "at" sounds better to me than "in," but that might be regional. Signed, someone who used to work for a utility company (but not at a power plant). – Elizabeth Henning Feb 3 at 5:12
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    For the specific instance of power plant, you'd be correct Elizabeth, but conceivably if a power plant was self-run (however unusual) e.g. by Mr Burns of Simpsons fame, it would be correct. – Ryan The Leach Feb 3 at 7:44
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    The in/at distinction is correct but not really followed to the letter by most speakers. The distinction mostly doesn't matter here since the intention of the message is to convey employment rather than precise location. – Flater Feb 3 at 10:37
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    @ElizabethHenning - That's a good point. Your examples highlight that "for" signifies a contractual (or employer/employee, master/servant) relationship, whereas "at" is just locational. – TechnoCat Feb 3 at 14:23

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