Please Explain Double Insulation

[Alfster]

Hi,

Just purchased a new wall light and it has no earth on terminal junction. Instructions say ‘double insulated - no earth required’.

Here is a picture:



How would this protect you if the wire from wall broke loose from this junction box and touched the casing which is metal? Or is it because it is in an enclosed junction box this is very unlikely?

Thanks

 

[littlespark]

exactly right.
the little joint box means that if a wire does come out, it cannot touch the metal casing as it is held within the plastic box.

The plastic box is designed so that when closed, the plastic also grips the cable so that it cant simply fall out.

Some boxes are better than others, but that's the idea.

The design of a lot of these decorative fittings leave a lot to be desired.

The fitting is deemed safe, if you follow the instructions, and use the supplied little plastic box

 

[LastManOnline]

The design of a lot of these decorative fittings leave a lot to be desired.

A number of years ago there was very little ambiguity about what "double insulation" meant. Usually it meant lots of plastic and deliberate physical isolation from live parts. Nowadays though, you can find yourself at times scratching your head as to how some accessories/appliances earned the term "double insulated"

 

[westward10]

Double insulation should have two layers of insulation or a single layer of reinforced insulation, to me that has neither.

 

[Alfster]

Double insulation should have two layers of insulation or a single layer of reinforced insulation, to me that has neither.

Thanks for comments people - informative and interesting.

What would official double insulated wire look like then. If that’s true that the fitting isn’t technically double insulated then they need to change their instruction ?


Unless they are trying to imply double insulated wire but really it’s double insulated because the box counts as the second insulation.

 

[westward10]

Unfortunately the market is flooded by these imports predominantly from China and compliance to their claims is tenuous to say the least. How many cables need connecting to it.

 

[DPG]

Double insulation should have two layers of insulation or a single layer of reinforced insulation, to me that has neither.

The bare metal blocks have two layers of plastic around them. The blue and brown wires have insulation and then plastic. I think it just about scrapes double insulation that doesn't it?

 

[westward10]

The bare metal blocks have two layers of plastic around them. The blue and brown wires have insulation and then plastic. I think it just about scrapes double insulation that doesn't it?

The terminal screw side will have one layer.

 

[DPG]

The terminal screw side will have one layer.

Good point. It should have a little square clip on piece over the inner chamber.

 

[LastManOnline]

A number of years ago there was very little ambiguity about what "double insulation" meant. Usually it meant lots of plastic and deliberate physical isolation from live parts. Nowadays though, you can find yourself at times scratching your head as to how some accessories/appliances earned the term "double insulated"

A reply to my own post. That's a first?. I would like to amend "scratching your head" to "having absolutely no doubt". This week I installed 2 metal fittings from IKEA, made entirely from metal. They also threaded the lampholder supply cable through the "knuckle" for the lampholder. This is simply a "class 1" fitting that has been designated a "class 2".I believe the "double insulated" principle has been diluted to the point that where its becoming meaningless

 

[littlespark]

A reply to my own post. That's a first?. I would like to amend "scratching your head" to "having absolutely no doubt". This week I installed 2 metal fittings from IKEA, made entirely from metal. They also threaded the lampholder supply cable through the "knuckle" for the lampholder. This is simply a "class 1" fitting that has been designated a "class 2".I believe the "double insulated" principle has been diluted to the point that where its becoming meaningless

In this example, what is the connector like? is it a small plastic box containing the connectors? If so, then a loose cable would be held inside the plastic, not able to touch the metal.
Also the cable going through the knuckle is sheathed, adding some mechanical protection.

It passes for "double insulated"

 

[LastManOnline]

In this example, what is the connector like? is it a small plastic box containing the connectors? If so, then a loose cable would be held inside the plastic, not able to touch the metal.
Also the cable going through the knuckle is sheathed, adding some mechanical protection.

It passes for "double insulated"

No arguement with the fact that it's been "passed". But compare it to a double insulated fitting from 30 years ago?
Would it have passed back then?