Cable protection (domestic garage), use of met-clad boxes

[rlc]

Is there a need/requirement to use conduit (i.e high impact uPVC) in order to provide additional mechanical protection to the cable routed inside a domestic garage.

I've seen the folowing cases:
(i) clipped directly to the blockwork
(ii) clipped to wooden battens
(iii) routed inside metal/uPVC conduit.

Not all use met-clad boxes, quite a few with plastic

I understand all to be acceptable methods? I'm thinking of the various reasons and can only come up with cosmetics, increased risk of mechanical damage, minimum cost. Other than ensuring all the components used are fit-for-purpose (IP rated if necessary etc etc ) I can only assume all combinations are acceptable but down to the personal touch?

Can anyone clarify this further?

~rlc

p.s I'm not a pro-spark - did an "EAL Level 2 VRQ for Domestic Installers" course and have a hunger to learn

 

[rlc]

Possibly explained in the "design" aspect -

Design : 131-01-01 the proper functioning of the electrical installation for the intended use.

Therefore selection from Table 4A1 Method 1 or Method 3 comes from this...if in the design process you feel there is a need for additional mechanical protection then method 3 should be used, if not then method 1 OK.....

Now I don't get the combo ..Met-clad boxes + method 1

 

[plugwash]

I do, plastic surface boxes are very easilly damaged in my experiance, far more so than surface clipped cable (especially if the cable is sensiblly routed).