2 ms·

You mean that the earth cable should run uninterrupted as a single wire from the connector of the device to the power cabinet?

OJFord 3y ago
Take a ceiling rose light fitting for example; you have: - twin core & Earth line - twin core & Earth to next fitting (or back to cabinet to complete the ring) - live to switch & switched live return - flex live & neutral (+ Earth if not double insulated) to light fitting those 2-3 Earths obviously need to be electrically connected, and that is not supposed to be done with a multipoint terminal block. They are supposed to be under a single screw in the light fitting say, or twisted together & sleeved. I believe it's thought that it reduces the chance of failure - one connection to check vs. a terminal block of three 'connections' where it's easy with solid core to think that they're secure when actually the middle one isn't, it's just roughly prevented from slipping out by the stiffness of the others, and potentially isn't a good electrical connection.
- Maxion 3y ago
  The UK electric code is wild. A ceiling rose light fixture in Finland has three wires: - Earth - Neutral - Live
  - OJFord 3y ago
    It can be like that, it's not a requirement, but once you know what's going on it's actually quite convenient to have the chaining. Not if you're trying to stuff it all in a small fitting that wasn't designed for it, but otherwise. I suspect Finnish spotlights are similar - they run in a chain not all individually to the switch? So only the last one has just the feed and nowhere to go? Difference is in the UK we have 'ring' circuits, where the 'end' as it were goes back to the consumer unit (power cabinet). It's mostly a post-war hangover: if the load is assumed fairly even then it means you can use half the wire diameter vs. not having the return, which was thought with typical and logical layout would mean less cable overall, since the 'end' would already be back around the other side close to the CU again. It has some safety advantage too, but AIUI it's slowly fading out of vogue for new installations and it will likely end eventually. (Some critique it that with modern patchy load distribution it actually now ironically requires more copper than the equivalent radial circuit, and probably not post-war level but copper's expensive again.)

OJFord 3y ago

Take a ceiling rose light fitting for example; you have: - twin core & Earth line - twin core & Earth to next fitting (or back to cabinet to complete the ring) - live to switch & switched live return - flex live & neutral (+ Earth if not double insulated) to light fitting those 2-3 Earths obviously need to be electrically connected, and that is not supposed to be done with a multipoint terminal block. They are supposed to be under a single screw in the light fitting say, or twisted together & sleeved. I believe it's thought that it reduces the chance of failure - one connection to check vs. a terminal block of three 'connections' where it's easy with solid core to think that they're secure when actually the middle one isn't, it's just roughly prevented from slipping out by the stiffness of the others, and potentially isn't a good electrical connection.

Maxion 3y ago
The UK electric code is wild. A ceiling rose light fixture in Finland has three wires: - Earth - Neutral - Live
- OJFord 3y ago
  It can be like that, it's not a requirement, but once you know what's going on it's actually quite convenient to have the chaining. Not if you're trying to stuff it all in a small fitting that wasn't designed for it, but otherwise. I suspect Finnish spotlights are similar - they run in a chain not all individually to the switch? So only the last one has just the feed and nowhere to go? Difference is in the UK we have 'ring' circuits, where the 'end' as it were goes back to the consumer unit (power cabinet). It's mostly a post-war hangover: if the load is assumed fairly even then it means you can use half the wire diameter vs. not having the return, which was thought with typical and logical layout would mean less cable overall, since the 'end' would already be back around the other side close to the CU again. It has some safety advantage too, but AIUI it's slowly fading out of vogue for new installations and it will likely end eventually. (Some critique it that with modern patchy load distribution it actually now ironically requires more copper than the equivalent radial circuit, and probably not post-war level but copper's expensive again.)