"Screwit" connectors

[fat-tony]

In another thread, Nigel had mentioned that you cannot use "Screwit" connectors, or Marettes as we call them in Canada, for electrical wiring in the UK and elsewhere. Google returns very little about them, but I did find a picture of them **broken link removed** .


I'm curious. What do you use to tie mains wiring together instead of these? In my limited experience, these work excellent, and as long as they're properly twisted together, seem pretty safe.

Edit: Looks like I should have read the whole thread. Ignore this please

 

[andrew2022]

junction box

 

[jbeng]

Also known in the US as "wire nuts" ...

 

[Dean Huster]

Insufficient answer for us poor Yanks, Andrew. In the U.S., we also use junction boxes. As a matter of fact, the NEC (National Electrical Code written by the National Fire Protection Association) is pretty much the law of the land as adopted by the various municipalities. If there's a wire nut in use, it must be located within a junction box, whether it's a dedicated box used only for joining the wires of various circuits or within a box into which a receptacle, switch or fixture is also mounted.

So, how are the wires actually attached to each other, specifically wires leading from a main panel circuit breaker that service several fixtures and/or switches leading to fixtures? The only problem that we've ever had in the U.S. was the use of aluminum wire (we pronounce it as written -- uh-LOO-mih-num vs. al-you-MIN-ee-um) and that's mostly been solved -- by not using aluminum! Wire nuts are our main connecting devices, specialty ones with seals and silicone grease for underground use.

Dean

 

[Nigel Goodwin]

In the UK a 'junction box' has threaded brass slots, you insert the wires into the slot and tighten the screw down on to the wires. Far more secure than simply twisting two wires together and covering them with a plastic nut.

Someone actually posted a picture of one in the previous thread, although it may have been closed.

These though are fairly rarely used, most UK wiring is directly from the fuse box to where it needs to go, mains sockets are done on a ring main, usually one for each floor - where the wire goes from the fusebox to each socket in turn, then back to the fuse box. This gives double the current handling capacity that a simple spur connection can - you use 2.5mm twin and earth cable, rated at 27A (in free air), giving 54A worth of cable on the ring.

Lighting circuits are done using thinner cable, usually suitable connections for switches are part of the light fittings, but if not you would use junction boxes to provide the required extra connections for the switch.

Probably the main use of junction boxes is tapping in to existing cables to add extra sockets or lights.

Here's a picture of a junction box that's open: