when he worked in the central office

English as a Second Language English Vocabulary, Grammar and Idioms
1

[color=red]1-I saw him regularly for three years when he worked in the central office.
[color=darkblue]2-I saw him regularly for three years, when he worked in the central office.

Is there a difference in the meanings of these sentences? The only difference is the comma after ‘years’.

In which case:
a-He worked in the central office for three years
and in which:
b-He worked for more than three years in the central office

I think 1 corresponds to:
When he worked in the central office, I saw him regularly for three years.

which corresponds to b.

Gratefully,
Navi.

Happy New Year.

2

There is no significant difference. The comma indicates a pause so the information is separated. The focus in (1) includes where he worked. The focus in (2) relates to the fact that he was seen regularly, where he was seen is less important.

Neither sentence indicates clearly how long ‘he’ worked in the central office. It might be the speaker who was there for three years. However, having said that, it is likely in both sentences that ‘he’ worked there for three years while the speaker worked there longer.