The phrase "are useless when the" is correct and usable in written English.
It can be used to describe a situation where something loses its effectiveness or value under certain conditions.
Example: "These tools are useless when the power goes out, as they rely on electricity to function."
Alternatives: "are ineffective when the" or "serve no purpose when the".
Televisions and computers are useless when the power is out.
They are useless when the rabies is advanced, so doctors opted in Jeanna's case for the experimental treatment.
Cordless phones that require power are useless when the power goes out.
Thus, the correction technologies are useless when the classification tasks are robust to class imbalance.
All measured parameters are useless when the sensor position shifts during the test.
However, there is a big downside to this approach: Heat tape is useless when the power goes out — as it often does when temperatures drop below freezing.
And, if so, what's an embattled company to do? Eric Dezenhall, a communications strategist in Washington who worked in the White House for President Ronald Reagan, argues that the standard playbook is useless when the facts are sufficiently distasteful.
They seem to perfectly capture a fear, floating in the culture, that a generation of preoccupied parents has been raising a generation of children full of sophisticated knowledge that is useless when the power goes out or the batteries die.
Traditional libel damages awards are useless when defendants lack money, and court enforcement of injunctions is useless when the defendants are effectively anonymous, or overseas, or are unable to remove the libelous material (for instance, from sites such as RipOffReport, which doesn't allow people to remove their own posts).
However, this scheme is useless when the attackers cooperate to forge the fake reply packets.
Then, a perfect matching between data and model is useless when the errors of the data are comparably large or small.
