Earth and lighting.

[Simon Mountford]

About to fit metal lights to ceiling and find there's no
earth. How necessary is it? Obviously, the intructions
with the fittings state that the unit must be earthed. It'll
be bit of a pain to do but I'd hate to wish that I had done it.
On the other hand I'd rather not if it's not really needed.
Distribution board is RCCB.
Tia.

 

[w_tom]

It really is not earth. It is a safety ground that keeps
humans from being electrocuted. However code also does permit
a solution - a GFCI placed on that circuit would accomplish
same. However all outlets and fixtures then require a label
that reads "No equipment ground" so that future humans
understand what kind of protection now exists.

Instructions sometimes confuse safety ground with earthing.
The two grounds must be interconnected. But that light
fixture required safety grounding - for human safety.

 

[Kilowatt]

I think it is interesting that NEC people and engineers believe that adding
a tag that says "No equipment ground" is needed so the customer understands
the instillation. That tag makes things clear as mud.

It is kind of like requiring green insulation for small wire instead of
phasing tape. If someone doesn't know what the green tape is for then
having green insullation somehow clears everything up.

Your suggestion is sound. The thinking behind the tag seems meanless to me.

 

[w_tom]

I did not realize the OP was in Britian. This changes
things slightly. The principles are same. But, for example,
Britian uses RCDs and not GFCIs. Also, the way some Brits
talk, Britian has no electric wires without a safety ground.

The label "No Equipment Ground" is required by code in the
US as part of a solution to this problem. Label's meaning is
quite clear as defined by code. I suspect from other
responses that UK has no equivalent label defined by code.

RCD would provide protection to a light fixture without
safety ground, but I don't believe the code specifically
states that an RCD is a solution to this problem. RCD is not a
great solution because RCDs are electronic devices that can
fail - leaving no indication that protection no longer exists.
Those more familiar with British codes must answer whether
that RCD suggestion is a 'legal' solution.

 

[Kilowatt]

I think it is interesting that NEC people and engineers believe that adding
a tag that says "No equipment ground" is needed so the customer understands
the instillation. That tag makes things clear as mud.

It is kind of like requiring green insulation for small wire instead of
phasing tape. If someone doesn't know what the green tape is for then
having green insullation somehow clears everything up.

Your suggestion is sound. The thinking behind the tag seems meanless to me.