First of all, I am getting an electrician to put this right and I'm not going to work on the circuit, but I would like to understand what is going on, especially so I don't get any wool pulled over my eyes. Basically we have a lighting circuit with incomplete earthing (electrician says continuity broken at some point, most likely between hall and landing). As I want to fit metal fittings, I need to get this sorted.
I find socket circuits easier to understand because they're a simple 3 wires in, 3 wires out, with all colours matching up. Lighting circuits seem to be far more complicated, with colours that should mean neutral looking like they're actually linking to live, "common" terminals, a switch in the hall that controls the landing but not vice versa, loads of junction boxes. I just can't get my head around it.
Here is an overview of the hall/ landing circuit from what I can make out:
- 2 switches in hall on one switch plate, with two cables coming from ceiling into back box:
- 1 switch for hall light has twin red and black with snipped off earth. Red goes to "common" and black is sleeved red and goes to L1. Then there is a red fly-lead from the common on the hall switch to the common on the landing switch (in the same switch unit).
- 1 switch for landing light that has a twin red and black without earth, with red feeding L1 and black (sleeved red) feeding L2.
1 switch in landing:
- 1 twin red and black with snipped off earth cable comes up from the floor and feed L1 and L2. Then a SINGLE red cable comes down from the loft to feed the common. Tracing this single red cable it goes up to a junction box in the loft, which has an onward connection to the landing light and the lighting circuit in the loft. It also has a single earth feeding in from somewhere. NB. The snipped off earths were tested and do not go anywhere.
Does this make sense? Electricians are all wanting to charge by the hour rather than quote (without even looking at it), which I can understand but it's a bit like a blank cheque. Other lights on the same circuit are earthed in the switch and light fitting, with continuity tested between the two, so the break in the circuit must be with this hall/landing set up. If I could find a wiring diagram that explains how the typical hall/landing should be (2 way downstairs, 1 upstairs) I might be able to understand.
I find socket circuits easier to understand because they're a simple 3 wires in, 3 wires out, with all colours matching up. Lighting circuits seem to be far more complicated, with colours that should mean neutral looking like they're actually linking to live, "common" terminals, a switch in the hall that controls the landing but not vice versa, loads of junction boxes. I just can't get my head around it.
Here is an overview of the hall/ landing circuit from what I can make out:
- 2 switches in hall on one switch plate, with two cables coming from ceiling into back box:
- 1 switch for hall light has twin red and black with snipped off earth. Red goes to "common" and black is sleeved red and goes to L1. Then there is a red fly-lead from the common on the hall switch to the common on the landing switch (in the same switch unit).
- 1 switch for landing light that has a twin red and black without earth, with red feeding L1 and black (sleeved red) feeding L2.
1 switch in landing:
- 1 twin red and black with snipped off earth cable comes up from the floor and feed L1 and L2. Then a SINGLE red cable comes down from the loft to feed the common. Tracing this single red cable it goes up to a junction box in the loft, which has an onward connection to the landing light and the lighting circuit in the loft. It also has a single earth feeding in from somewhere. NB. The snipped off earths were tested and do not go anywhere.
Does this make sense? Electricians are all wanting to charge by the hour rather than quote (without even looking at it), which I can understand but it's a bit like a blank cheque. Other lights on the same circuit are earthed in the switch and light fitting, with continuity tested between the two, so the break in the circuit must be with this hall/landing set up. If I could find a wiring diagram that explains how the typical hall/landing should be (2 way downstairs, 1 upstairs) I might be able to understand.
