I pal of mine intends to replace his ancient CU with something a bit more modern. He'll probably have to extend the cable ends inside the CU. The problem is that most of the existing cable is 7/0.029 and 3/0.029 or something similar. Are crimps effective with stranded cable?
TIA -
He needs to check a few things first :-)
Most definately.
Some things to check for...
TRS Imperial? Black rubber with BICC embossed into the side, tinned multi-strand, sometimes with an integral CPC (FTE), sometimes without an integral CPC (FT). Beware when bent the cable can not only split circumferentially along the outside of the bend, but split through the insulation exposing the conductor. Not unusual to find the rubber dry, cracked & falling off the wiring accessory terminations. In a loft you can find bare tinned stranded wandering about, the rubber has actually completely perished off. Beware an IR test suggesting a TRS cable is safe, because air is a perfect insulator :-)
Lead sheathed imperial? Can still be found, particularly in obscure places such as under cast- iron baths.
PVC sheathed imperial? Larger sizes had PVC insulation and can exude green gunge at terminations, smaller sizes actually had polythene which can crack if subject to heating (the red will appear a quite genuine harmonised brown). Smaller sizes can be very fragile which can lead to bad contacts & overheating if overtightened (just as with modern 1.0mm solid conductors).
Junction box heaven or hell? The loft may have a scattering of jn-boxes with just 2 wires to each ceiling rose. Bad connections here can result in localised overheating so beware putting hands on anything live. There may also be screwits, a small ceramic cap screwed down over stranded tinned cable to create a junction, these can really be a surprise and get rid of ASAP. Underfloor can be a central bundle of jn-box under the landing floor, or a mess scattered about, expect jn-box (or terminal strip n bit of tape) over any centre-lights, stuck under a bed made from the bismark, under an anvil, under laminate. Clearly if you can eliminate jn-boxes that is a good thing, or use a
2G accessible blankplate just below the ceiling in a discrete area to thereby achieve truly accessible junctions.Hall 2-way lighting may have a borrowed live/neutral if just a flat- twin (no earth) strapped from hall-down to hall-up light. However, good sparks & elec-eng wired the upstairs light as a ring to avoid this, you will have 3 FT(E) at the CU. If you have a borrowed live/ neutral you will need to first put Up & Down on the same RCD or RCBO - a quick check is split them across RCBO and with one hall light switch position the RCBOs will trip off re borrowed neutral/live. Usually the Neutral is off the upstairs jn-box and the Live off a downstairs circuit such as a porch light switch below or jn-box under the landing. To fix a borrowed neutral/live you need to find out what you have, ideally run 3C+E between the light switches in oval (any wallpaper left, check the loft or cupboards?), and put a corrective link in 6181Y (6141Y) 1.0mm brown or blue respectively.
Backboxes made of wood with metal grippers (MK)? You can get class-II backboxes (no CPC required), they are MK ESU/9/ML and usually a PITA to find since I mentioned them last (Senate Electrical will not ship them, they just play dumb). You can get equivalent on Ebay or from Clipsal (the latter are BS4662, no CE label tho, 25/35/45/55mm depth). GET & Appleby do some, I think Marshall do too. Alternatively you can use metal backboxes with plastic screws, frankly I prefer a Class-II backbox with Class-II wiring accessory obviously.
Visual inspection everywhere. You need to do that before changing the CU. Check every ceiling rose, every light switch, every socket. In particular check for bad-DIY (there is more bad than good) and check for bad-kitchen-fitter (I am not sure there is good) and bad-not- real-spark (because they tend to do things like terminate the sheath outside the box, insulated cores run behind metal box & wall, metal box crushing the insulated cores flat, thro the back without a grommet, lots of callouts engineered in, no CPC sleeved along with new PVC crimped to TRS under floorboards or out of sight - yes, been there and had about 12yrs of hell sorting it out with a lot of photos, a lot of cost, a lot of pain).
SI2006 (Part P) does make a CU change, not an enclosure change, notifiable works. However Part P does not make replacing a circuit notifiable using the definition of "circuit" under BS7671 which is starting/ending at a circuit protective device. So you can take the rest of your life to replace each cable thereafter as necessary as & when you redecorate. If the existing install is unsafe, I would make it safe rather than "Part P says I can not" and the place burns down. This is particularly true if your archaic consumer unit is a Wylex open backed wooden unit.
Likewise if you are not happy with a circuit, condemn it and surface wire temporarily - it can be the best thing.
Alternatively you have 1960s PVC imperial in good condition, good install, CPC present, modern backboxes, just an old CU. Plenty of those out there, RCD protection for anything outside should be considered mandatory. The DIY-store "waterproof outside socket kits" be it pre-made flex or pre-made SWA are completely legal under SI2006 because it has specific exemption for such. If you have to use one of those or a plug-in RCD socket, they do save lives.
He needs to check a few things first :-)
Most definately.
Some things to check for...
TRS Imperial? Black rubber with BICC embossed into the side, tinned multi-strand, sometimes with an integral CPC (FTE), sometimes without an integral CPC (FT). Beware when bent the cable can not only split circumferentially along the outside of the bend, but split through the insulation exposing the conductor. Not unusual to find the rubber dry, cracked & falling off the wiring accessory terminations. In a loft you can find bare tinned stranded wandering about, the rubber has actually completely perished off. Beware an IR test suggesting a TRS cable is safe, because air is a perfect insulator :-)
Lead sheathed imperial? Can still be found, particularly in obscure places such as under cast- iron baths.
PVC sheathed imperial? Larger sizes had PVC insulation and can exude green gunge at terminations, smaller sizes actually had polythene which can crack if subject to heating (the red will appear a quite genuine harmonised brown). Smaller sizes can be very fragile which can lead to bad contacts & overheating if overtightened (just as with modern 1.0mm solid conductors).
Junction box heaven or hell? The loft may have a scattering of jn-boxes with just 2 wires to each ceiling rose. Bad connections here can result in localised overheating so beware putting hands on anything live. There may also be screwits, a small ceramic cap screwed down over stranded tinned cable to create a junction, these can really be a surprise and get rid of ASAP. Underfloor can be a central bundle of jn-box under the landing floor, or a mess scattered about, expect jn-box (or terminal strip n bit of tape) over any centre-lights, stuck under a bed made from the bismark, under an anvil, under laminate. Clearly if you can eliminate jn-boxes that is a good thing, or use a
2G accessible blankplate just below the ceiling in a discrete area to thereby achieve truly accessible junctions.Hall 2-way lighting may have a borrowed live/neutral if just a flat- twin (no earth) strapped from hall-down to hall-up light. However, good sparks & elec-eng wired the upstairs light as a ring to avoid this, you will have 3 FT(E) at the CU. If you have a borrowed live/ neutral you will need to first put Up & Down on the same RCD or RCBO - a quick check is split them across RCBO and with one hall light switch position the RCBOs will trip off re borrowed neutral/live. Usually the Neutral is off the upstairs jn-box and the Live off a downstairs circuit such as a porch light switch below or jn-box under the landing. To fix a borrowed neutral/live you need to find out what you have, ideally run 3C+E between the light switches in oval (any wallpaper left, check the loft or cupboards?), and put a corrective link in 6181Y (6141Y) 1.0mm brown or blue respectively.
Backboxes made of wood with metal grippers (MK)? You can get class-II backboxes (no CPC required), they are MK ESU/9/ML and usually a PITA to find since I mentioned them last (Senate Electrical will not ship them, they just play dumb). You can get equivalent on Ebay or from Clipsal (the latter are BS4662, no CE label tho, 25/35/45/55mm depth). GET & Appleby do some, I think Marshall do too. Alternatively you can use metal backboxes with plastic screws, frankly I prefer a Class-II backbox with Class-II wiring accessory obviously.
Visual inspection everywhere. You need to do that before changing the CU. Check every ceiling rose, every light switch, every socket. In particular check for bad-DIY (there is more bad than good) and check for bad-kitchen-fitter (I am not sure there is good) and bad-not- real-spark (because they tend to do things like terminate the sheath outside the box, insulated cores run behind metal box & wall, metal box crushing the insulated cores flat, thro the back without a grommet, lots of callouts engineered in, no CPC sleeved along with new PVC crimped to TRS under floorboards or out of sight - yes, been there and had about 12yrs of hell sorting it out with a lot of photos, a lot of cost, a lot of pain).
SI2006 (Part P) does make a CU change, not an enclosure change, notifiable works. However Part P does not make replacing a circuit notifiable using the definition of "circuit" under BS7671 which is starting/ending at a circuit protective device. So you can take the rest of your life to replace each cable thereafter as necessary as & when you redecorate. If the existing install is unsafe, I would make it safe rather than "Part P says I can not" and the place burns down. This is particularly true if your archaic consumer unit is a Wylex open backed wooden unit.
Likewise if you are not happy with a circuit, condemn it and surface wire temporarily - it can be the best thing.
Alternatively you have 1960s PVC imperial in good condition, good install, CPC present, modern backboxes, just an old CU. Plenty of those out there, RCD protection for anything outside should be considered mandatory. The DIY-store "waterproof outside socket kits" be it pre-made flex or pre-made SWA are completely legal under SI2006 because it has specific exemption for such. If you have to use one of those or a plug-in RCD socket, they do save lives.
Calm down mate. Frank is not stupid.
The answer is YES the crimps will work with the suggested cable.
Cheers
Adam
It was more a "for the record post" re ancient CU and any lurkers :-)
Yes. Here's another way I used.
It fits in to some extent with a recent 60s installation I checked out and have suggested several improvements to.
I wouldn't worry about back free wylex, apart from the exposed terminals inside. You can still get (3ka rated)mcbs to fit which are fine in most domestic situations. Other factors (below) may have influence)
In this installation (mainly PVC wiring) I recommended.
1 finding out why ring wasn't. (Phantom socket installed on first fix and ignored on second after plasterers had encased the back box. they are pleased with the extra socket they now have). Done. 2 Sort out main bonding Still to do. 3 I condemned the metal light switches and fittings on lighting circuit without PE. Minimum ecommendation replacing with class 2. 4 Bathroom AAAARRRRGGGGHHHHH! Large vent axia in wall next to bath, about shoulder height I still haven't recovered from shock of discovering it!. Two sockets (one 3m from bath for fixed fire, I suggested FCU for that no take up). Other socket (used for radio etc. about 1.5m from bath. replace with razor socket -- no take up). 5 split ring main, and sort out multiple sockets on kitchen spurs, perhaps fused spurs for some. No response so far. 6 replace CU with (split) RCD protection, to mitigate some of the other problems. no response other than to say the CU was (partly) upgraded to MCBs fairly recently.Basically everything in house is reasonable quality 60s (CH boiler is cast iron (reliable) 70s replacement of original 60s solid fuel) with minor (apart from safety) changes such as brass sockets and switches. 40 grand could easily be spent upgrading which he doesn't want to start, so he's stuck with several undesirable safety 'enhancements'.
You could slap some of it in here where appropriate:
I'd definitely ask for more info. End users wanting to replace old fusesboxes too often gain almost nothing by doing so. If the fixed wiring is rubber, I'd be a bit wary of moving it about. If the install's a mess, the significant safety issues are normally elsewhere than the CU.
OTOH if the CU is a piece of slate with bare fuse wires screwed onto the front, maybe it is time!
NT
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