Lighting in the loft

[BrettRogersUK]

Hi Everyone,

At present I have to get an extension lead and plug into a socket then trail the cable up into the loft to plug a light in up there and it's all very pretty dangerous having these wires trailing so I thought I'd do something about it and install loft lighting up there.

I have seen this guide online (https://www.diydoctor.org.uk/projects/loft-light.htm) about wiring it up and have bought everything I need to do it but I've just discovered that I've mistakenly bought a 30A junction box instead of a 5A one. Will this matter at all? If so I'll get a 5A one.

I'm gonna be putting this in at the weekend I think. I'm pretty sure of everything I need to do to get the light sorted.

The light I have purchased is this one (https://www.toolstation.com/mark-lighting-slimline-led-batten/p89463) which only has a L & N it doesn't have an earth connection. So Am I right in thinking that as I'm using T&E 1.5mm cable I can just terminate the earth wire in a suitable block and tape it up inside the light?

I look forward to your reply.

Kindest Regards,

Brett

 

[JohnW2]

I've just discovered that I've mistakenly bought a 30A junction box instead of a 5A one. Will this matter at all? If so I'll get a 5A one.

No problem. If you find that the 1.5mm² (1mm² would do) conductors are a bit 'lost' in the larger terminals of the 30A JB, you could just 'bend over' the ends, so that it was 'doubled'.

The light I have purchased is this one (https://www.toolstation.com/mark-lighting-slimline-led-batten/p89463) which only has a L & N it doesn't have an earth connection. So Am I right in thinking that as I'm using T&E 1.5mm cable I can just terminate the earth wire in a suitable block and tape it up inside the light?

Yep, you just need to be sure that the earth wire can't touch anything else - the connector block ('tucked out of the way' somewhere) should achieve that without any tape.

Kind Regards, John

 

[ericmark]

Unless your talking about maintenance free where the connectors may not work correctly with undersized cable there is no problem with 30 amp junction box. It seems odd that an aluminium lamp does not have an earth, are you sure it is class II it will have this

mark if class II.

 

[BrettRogersUK]

No problem. If you find that the 1.5mm² (1mm² would do) conductors are a bit 'lost' in the larger terminals of the 30A JB, you could just 'bend over' the ends, so that it was 'doubled'.
Yep, you just need to be sure that the earth wire can't touch anything else - the connector block ('tucked out of the way' somewhere) should achieve that without any tape.

Kind Regards, John

Thanks John, Just what I thought.

Cheers,

Brett

 

[BrettRogersUK]

Unless your talking about maintenance free where the connectors may not work correctly with undersized cable there is no problem with 30 amp junction box. It seems odd that an aluminium lamp does not have an earth, are you sure it is class II it will have this

mark if class II.

Yeah, it says in the Fitting and operation instructions under the specification section that the protection class is listed as class II.

Regards,

Brett

 

[plugwash]

On a metal cased class II fitting you need to be careful so as not to compromise the class II rating. Generally the fitting will include an insulated terminal enclosure and you *MUST* ensure that any single insulated cores are contained within the terminal enclosure.

Unfortunately the space inside the terminal enclosures is often very limited, leaving no space for niceities like terminating the earth wire in a terminal block. Cutting it short while generally undesirable may well be the least bad option.

Personally I don't think such fittings should be sold, it's just too easy for them to be installed in ways that compromise their safety ratings.

 

[JohnW2]

Unfortunately the space inside the terminal enclosures is often very limited, leaving no space for niceities like terminating the earth wire in a terminal block. Cutting it short while generally undesirable may well be the least bad option.

True - although the block for the earth wire does not necessarily have to be within the 'terminal enclosure'.

Personally I don't think such fittings should be sold, it's just too easy for them to be installed in ways that compromise their safety ratings.

In many cases (probably including this one), I'm inclined to agreed. Indeed, I don't really see why they don't just let the metal be earthed and call in Class I (but see **).

I realise (and often argue!) that to unnecessarily earth bits of touchable metal is theoretically not desirable, but that assumes that there is no downside (risk) associated with not earthing it. However, when (as probably in this case), there is a possible downside', then to make it Class I would seem (where possible) to be more wise.

[ ** I suppose that one possible reason for things being constituted as Class II might, at least in some cases, be that if it contains any single-insulated live parts, it would presumably have to be completely enclosed in earthed metal in order to be acceptable as Class I - which may not always be practicable and/or 'convenient'. ]

Kind Regards, John

 

[SUNRAY]

[ ** I suppose that one possible reason for things being constituted as Class II might, at least in some cases, be that if it contains any single-insulated live parts, it would presumably have to be completely enclosed in earthed metal in order to be acceptable as Class I - which may not always be practicable and/or 'convenient'. ]

Kind Regards, John

Removing this comment entirely from the flow of the thread, I see no reason for it, or and arguement for it.
I can think of loads of examples of class II products containing massive totally uninsulated chunks in non metalic enclosures and sometimes metalic parts closely associated with those uninsulated items extend outside the plastic enclosure.

Equally there are many part metal/part plastic products in both class I and class II categories.

 

[JohnW2]

Removing this comment entirely from the flow of the thread, I see no reason for it, or and arguement for it.

If the 'it' you're referring to is having equipment (like lights) with exposed metal parts in which those metal parts are not earthed, as I said, I can think of few reasons/excuses, other than the rather unconvincing one (essentially that of 'manufacturing convenience') I mentioned.

I can think of loads of examples of class II products containing massive totally uninsulated chunks in non metalic enclosures ...

That's fair enough. As I'm always saying, I have countless "Class II" items which have absolutely no exposed metal parts, and therefore could not possibly be Class I.

....and sometimes metalic parts closely associated with those uninsulated items extend outside the plastic enclosure.

I'm not sure how that could be described as Class II.

As I often ask, if an item has no exposed metal parts (hence can't possibly be Class I), but also does not have "double or re-inforced" insulation (hence doesn't qualify as "Class II") then 'what is it?' - maybe 'not allowed', or what?

Kind Regards, John

 

[SUNRAY]

I'm not sure how that could be described as Class II.

As I often ask, if an item has no exposed metal parts (hence can't possibly be Class I), but also does not have "double or re-inforced" insulation (hence doesn't qualify as "Class II") then 'what is it?' - maybe 'not allowed', or what?

Kind Regards, John

I think of thing like power tools with a mains motor and metal chuck.

 

[JohnW2]

I think of thing like power tools with a mains motor and metal chuck.

That metal chuck will (I presume always, if it's genuinely Class II) be separated from any live parts by "double or reinforced insulation" (nylon gears, casing etc.) - otherwise it could not be classified and marked as Class II, could it?

Kind Regards, John

 

[SUNRAY]

That metal chuck will (I presume always, if it's genuinely Class II) be separated from any live parts by "double or reinforced insulation" (nylon gears, casing etc.) - otherwise it could not be classified and marked as Class II, could it?

Kind Regards, John

And mucky grease full of...

I ALWAYS check for isolationwhen PATing and a horrible number are far too low resistance to allow a pass.

 

[JohnW2]

I ALWAYS check for isolationwhen PATing and a horrible number are far too low resistance to allow a pass.

Fair enough - but in so doing you are presumably acknowledge the fact that in order to qualify as Class II (i.e. pass a "Class II" PATest) the chuck has to have a very high resistance to live conductors.

Mind you, I have to wonder (and worry) about how low are the resistances you're seeing between chucks and live conductors?

Kind Regards, John

 

[SUNRAY]

I've had one in the shed for a while, over the weekend I'll try 'n dig it out & retest.

 

[JohnW2]

I've had one in the shed for a while, over the weekend I'll try 'n dig it out & retest.

Thanks - that will be interesting.

On the face of it, any measurable resistance between the chuck and live parts from which it is meant to be separated by "double or reinforced insulation" is rather a worry. Even at 1000V, one would not expect to be able to measure a resistance between two parts even if separated only by a single layer of very thin/flimsy (hence certainly not 'reinforced') insulation.

For what it's worth, I've just measured 4 Class II power tools picked at random (2 drills, one biscuit jointer and one mitre saw), all well-used and relatively filthy, and in all cases got ">1000 MΩ" at 1000V from the metal chuck (or other metal 'working parts') to both N and L (with and without the tool switched 'on'). I'll therefore be interested to hear what you find.

Kind Regards, John