[Advaita-l] A query from book " Hindu dharma " by Sri Chandrashekharendra Saraswati ( maha periyaval )

[Animesh via Advaita-l]

Sri mātre namah 
Namaste

I was studying " Hindu dharma " by sri Chandrashekharendra saraswati ( maha periyaval )
and find this passage 
" When we are not engaged in either of these two rites- that is when we are doing our office work or something else- the sacred thread must not rest on either shoulder and must be worn like a garland. (No one seems to observe this rule in practice now. Except during the rites for the fathers, most people have their sacred thread resting on their left shoulder. )  "
I tried to ask my elders about what peiyavaal is saying but they told me it's our custom to wear yagnopavitham on left shoulder not like garland .
Neither I find such of any reference in kaushika grihya sutra .
Please clarify .
( if possible please give any pramana because if sri chandrashekharendra saraswati ji is saying this then it should be there in our shAstra )


Regards 
Animesh