I'm contemplating a serious rewire/CU replacement and had a few questions:
- I'll be using SWA to feed the CU some distance from the incoming supply. I've read the excellent terminating SWA article on the wiki, but it is unclear about exactly what size SWA can be cut using bolt croppers. I'll probably be using 10mm2 or 16mm2 SWA - is it reasonable to expect bolt croppers to be fine for cutting these sizes?
- Is my supply TN-S or TN-C-S?
While I have seperate PE and N entering my building, the PE and N are connect together on my property. I have two wires (11kV?) coming onto my property, which terminate on a larger transformer on a telegraph pole. I can see the PE is provided from underground at the pole, and is connected to the N supply from the transformer. So my thinking is that I'm TN-S if the transformer is considered the power source, but TN-C-S otherwise. Thoughts?
(Yes, I have asked my electricity supplier, but they have suggested that I contact the DNO. I haven't yet summoned up the energy to do this.)
- I'm considering using a metal CU. From doing a bit of research online it may be a requirement that the supply to this CU is protected by a 100mA time delayed RCD. However, I'm unclear as to whether this is only a requirement for TT systems or whether it's applicable to my scenario. I'll be digging out my 17th ed regs later, but can anyone let me know whether the RCD is a requirement here?
- I'm considering a three phase CU, and using this as a single phase CU. I'm unfamiliar with the internal construction of these CUs - is there generally any problems with using a TP CU as a single phase one? (The main obvious issue I've seen is that for the model I'm looking at a DP incoming switch is not available - so I'd have to use a TP one and leave one pole unused.
- Finally, any recommendations or brands to steer clear of? I've been looking at the Hager Invicta 3.
Thanks, Piers