Cable & earth query on low energy downlights

Deansplit · 17 Oct 2010

Is .75mm cable ok for low energy downlights?

Also, the loop in/out connector on the fire proof casing has 6 points (3 per side, labeled Live Earth & Neutral, naturally!) So presume each side is just an in and out for the continuous cable? But does the earth not need to ground somewhere on the casing or something... where does it go once reaches the end of the line?

wingcoax · 17 Oct 2010

I think if you look, the earth terminal will have a connection to the casing.

Deansplit · 17 Oct 2010

I wondered that, but when I grabbed the connector to wire the first one up it came off of the metal side strip it was attached to, so I looked to see if the earth wire/connector would touch the strip when fixed back on, but no sign!

Deansplit · 17 Oct 2010

...it actually says 'provision for earth connection' so presume not 100% necessary?

STI · 17 Oct 2010

are the units marked as double insulated

Deansplit · 17 Oct 2010

Not sure, will have to check tomorrow.

Thx

wingcoax · 17 Oct 2010

When you say metal side strip, is it a slim piece of metal that whent into the terminal? If so then that would provide the earth.

Taylortwocities · 17 Oct 2010

EDIT: ignore, wrong comment now deleted....

Deansplit · 18 Oct 2010

STI said:
are the units marked as double insulated

Just checked, yes L& N double insulated.

The earth connector casing definitely doesn't touch the metal strip which carries the connectors.

electronicsuk · 18 Oct 2010

Deansplit said:
Is .75mm cable ok for low energy downlights?

I would say no, as 524.1 states the following:

The cross-sectional area of each conductor in an a.c. circuit or of a conductor in a d.c. circuit shall be not less than the values given in Table 52.3, except as provided for extra-low voltage lighting installations according to Regulation 559.11.5.2.

Table 52.3 states the minimum CSA for sheathed and non-sheathed cables in power and lighting circuits to be 1.0mmsq. The use of 0.75mmsq conductors would only be permitted with flexible connections, which I would not personally consider fixed wiring to be.

STI · 18 Oct 2010

Deansplit said:
STI said:

are the units marked as double insulated

Click to expand...

Just checked, yes L& N double insulated.

The earth connector casing definitely doesn't touch the metal strip which carries the connectors.

OK so if its got the square in a square symbol the actual casing does not need to be earthed and they appear to have provided a terminal where you can just daisy chain the earths together instead of using some block or just taping up.

Deansplit · 18 Oct 2010

only be permitted with flexible connections

What are these? I've already used .75 now, an electrician said it'd be ok.

electronicsuk · 18 Oct 2010

Deansplit said:
only be permitted with flexible connections

Click to expand...

What are these? I've already used .75 now, an electrician said it'd be ok.

I haven't got my regs book in front of me right now so can't check to see if there is a specific definition, but I would interpret it to mean flexible cords used to supply portable appliances. Certainly, 1.0mmsq is quite specifically stated in table 52.3 to be the minimum CSA required for lighting and power circuits.

Your house isn't likely to burst into flames because of it, mind.

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Cable & earth query on low energy downlights

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