Tier 2 General to tier 2 General (Switch) Changing Employer

Hi All,

I am on tier 2 general till 2017 Dec, my sponsored company gone to administration on 7th dec ( made all redundant).
I was on SOC code 2124 level 6.

Now I found a new job they are going to issue COS in coming week but the role they offered is in SOC code level 3 (3113).

Is it ok to switch from level 6 to level 3.
Both seems to be in shortage occupation list.
Can I join and then apply for a Visa or do I need to get visa before commencing work.

Please help.
Manju

Note that under SOC code 3113 only the following jobs in the electricity transmission and distribution industry are shortage occupations:
a) commissioning engineer
b) substation electrical engineer

you will need visa before commencing work.

Thanks