How do detrmine the level of mechanical protection required, using the UK 16th regs

senario....
Install in a domestic garage one end, a work bench is fitted. So we know the T&E cabeling requires to be in conduit. But how do you decide if it should be plastic conduit or metal conduit?

Quote from 16th regs

522-06 Impact (AG)

522-06-02 In a fixed installation where an impact of medium severity (AG2) or high severity(AG3) can occur, protection shall be afforded by:
(i) the mechanical charicteristics of of the wiring system,or
(ii) the location selected,or
(iii) the provision of additional local or general mechanical protection,
or by any combination of the above.

So how do we determine the levels of severity, AG2 and AG3?

Hi Ken,
Am I to assume that the walls of the garage will be un-lined (bare studs, etc) around the workbench area?.
If it were lined, I would say that additional protection is not required, where the T+E wiring runs through the studs and dwangs(nogs).
But lets get away from that silly idea,
could you not use something like say mini-trunking?.
One thing I did in a garage here recently was, used a length of PVC ducting along the back of the workbench (200mm above the bench surface) and had 4-way socket-outlets every 2 metres along the ducting and built the sockets into the ducting itself.
I've never heard of this system before, is this a new thing?.
One thing I do know though Ken, the IP Code (Ingress Protection), has always had a third number to denote impact resistance for electrical enclosures and such materials, apparently the French use it, I'm not sure if it caught on anywhere else in Europe, I know that a few people here were never aware of it, or indeed the IP Code itself!.
Just my $0.02 worth.

Trumpy no probs mate.
If everyone that posted here payed their 2 cents worth in cash I would be a millionair

The garage is brick built.

This is just a table top exercise for one of my better students. Now normaly I would just run it in plastic conduit.
But when he asked if he should use plastic or metal I thought I would be smart and told him to look it up in the regs. But then he found out the regs only state what I have quoted.
I have never heard of this "impact rating" before and I can not find an expination in the regs for it.

The regulations here are notoriusly dificult to understand. So much so you get a certificated course just to be able read them (no joke) ask any UK electrician.
Still that is what sorts out the real electricians from the odd job guys...........

Should have added

We do use the IP rating in the UK. It works well personaly I think it is a great idea.

Ahh that explains a lot Ken.
On the surface installation.
I was assuming that the building was timber-framed. Grrr.
Not long after I first posted the reply, I realised that the building might be either brick or building block construction.
I always thought that Metallic conduit was reserved for Industrial places, not a Domestic installation.
Heavy-Duty PVC is used here in Industrial places and it affords good mechanical protection, it can be identified by it's Orange colour.

I'm not familiar with this AG system of measurement either. I can't see the typical domestic garage requiring metallic conduit,except perhaps in one or two specific areas if there was a real likelihood of damaga, e.g. a low-level run right where it could be hit with big trolley jacks or such like.

I just recently finished the wiring for a neighbor's new garage and workshop and used black PVC conduit throughout. (Not T&E though, just 2.5 singles.)

All I can find in our regs are phrases like "Adequately protected against mechanical damage". Which means it's up to us to decide wether to use plastic or metal conduit.

I've always wondered what type of impact would break plastic conduit pipe but not damage metal pipe ? Any ideas ?

The Australian wiring rules are just as vague and useless on the matter of determining the level of mechanical protection.
What really gets me is how corrugated PVC and rigid PVC conduit are both called medium duty yet corry can easily be crushed and cut open with a knife...what the?

I contacted "Kopex" last night through their web site and put this question to them.

Will let you know what reply I get

I also orderd a cataloge so see if there is any answer there for you briselec.