Johannes Gleim Aug 8, 2016:

@ Tony Thank you for explanation of "operate/run off/from"! This may go without saying for English native speakers, but not for no-natIve speakers like me and the asker. She is French. In this case, I was unsure, whether it has the meaning "to run from" or not. And this could had been the difficulty for EA, too.

Tony M Aug 7, 2016:

@ Daryo Of course it is! No need for anyone to cloud the issue with red herring side issues. This is perfectly normal, standard technical EN as commonly used in this type of document.

Tony M Aug 7, 2016:

@ Johannes 'to work / run off something' is perfectly normally EN, it's an inseparable phrasal verb (unlike in German) and we will say things like 'it runs off a battery'. In this usage, the 'off' could equally well be repalced with 'from' with no change in the meaning.

For it to mean it 'works WHEN NOT ON the mains supply' etc. would be a very INformal usage, and quite out of place in a technical document like this one; hence why it is important to take REGISTER into account as part and aprcel of any interpretation.

Daryo Aug 7, 2016:

I think that Tony and Johannes Gleim would agree that the key point that is being made implicitly is that this emergency power supply should produce enough power for at least two lifts - one for clients and one service lift, i.e. it's about minimum requirements regarding the power output of the emergency generators.

Johannes Gleim Aug 7, 2016:

@ Tony The difficult item is the position of the particle "off". "The elevator should operate off the generator supply" can easily be understood as "the elevators should operate without generator supply", what describes normal supply from the mains. Other meanings like "disabled", "away", "remote" make no much sense. Please explain, why the word order is correct and what is off.

Tony M Aug 7, 2016:

@ Johannes It is really very clear and straighforward; as you say, all lifts might be able to descend (= little power) using the emergency generator supply, and simply opening the doors wouldn't use much power either.
But after that, only 2 lifts would be operational, in order to economize precious generator power.
I don't see what is in any way unclear about the way it is exporessed here, given the normal sort of language used in specifications etc. in EN.

Johannes Gleim Aug 7, 2016:

@ EA I have also problems to catch the sense behind that phrase. Probably, all escalators are supplied from the mains. In case of power interruption all escalators must be capable to return to ground level. Descending and opening may be achieved by the weight of the cabin or by means of a buffer battery. The generator may start in case of such emergencies rather than to provide energy under normal operation mode, as it is capable to supply 2 escalators only.

The phrase may be read: "... should operate by/from the generator supply (with mains off)".

Is the editor a non-native speaker?

EA Traduction (asker) Aug 7, 2016:

Hi Tony, Yes this is when I send the question that I have understood the meaning of the sentence. Of course, the word "lift" relates to 1 guest and 1 service...

Tony M Aug 7, 2016:

@ Asker Oh dear me no, I'm afraid you are interpreting that quite wrongly!

To start with, they are talking about '1 guest lift' + '1 service lift'

And then it is nothing about those things making the generator supply work — you are misreading the EN word order.

1 guest lift + 1 service lift must be able to run off the generator supply — if there is a power failure, the emergency generator will start, but is not able to supply enough power to run ALL the lifts, so only one of each will be left operating.