5A Junction box

AJJewsbury: 
 

I worked with an electrician who always used them on lighting circuits with 6a breakers, is this common practice on domestic properties?

If common practice is anything like what I do, then it'd be more like avoiding junction boxes like the plague.

I much prefer to keep terminals accessible - looping in at lights or switches - is much preferred.

Junction boxes might sometimes be needed for additionals/alterations to existing circuits - though to be honest I'd probably go for a plastic box and some wago connectors these days. I can't remember when I last used a traditional round JB - certainly more than a decade ago.

    - Andy.

Sometimes the small circular junction boxes were good as they fitted through a hole in the ceiling allowing a new downlighter to be wired in. Also they were flame retardant and not just made of flimsy soft plastic.

Z.

I worked with an electrician who always used them on lighting circuits with 6a breakers, is this common practice on domestic properties?

If common practice is anything like what I do, then it'd be more like avoiding junction boxes like the plague.

I much prefer to keep terminals accessible - looping in at lights or switches - is much preferred.

Junction boxes might sometimes be needed for additionals/alterations to existing circuits - though to be honest I'd probably go for a plastic box and some wago connectors these days. I can't remember when I last used a traditional round JB - certainly more than a decade ago.

    - Andy.

Yes.

Zoomup: 
 

JDW: 
 

Are 5amp junction boxes acceptable on a 6amp lighting circuit?

I personally wouldn’t use them as they are too small, but if they are already fitted are they acceptable? 

Oh yes. The rating is only nominal. You say “already fitted.” Fitted to what?

Z.

I worked with an electrician who always used them on lighting circuits with 6a breakers, is this common practice on domestic properties?

Yes fine in my view, to require that 5 amp junction boxes be replaced when a 5 amp fuse is replaced with a 6 amp MCB is IMHO over pedantic.

The load probably wont exceed 5 amps, and with the general use of low energy lamps is unlikely to exceed even half that.

And in most situations the junction box wont be carrying the entire load of the circuit in any case.

And even if a full 6 amps did pass, I doubt that the terminals would even get warm. Most of the current will pass from one wire to the other wire when these are forced into close contact by the screws. Very little current will pass through the metal parts of the terminals. 

I would take the “5 amp” rating as meaning “not big enough to take the size cables used on power circuits” Rather than meaning “liable to overheat at over 5 amps”

JDW: 
 

Are 5amp junction boxes acceptable on a 6amp lighting circuit?

I personally wouldn’t use them as they are too small, but if they are already fitted are they acceptable? 

Oh yes. The rating is only nominal. You say “already fitted.” Fitted to what?

Z.