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- 10 Nov 2007
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I'm here in Austria and I've got a three phase electric cooker and I'm new to 3-phase but I've done a fair bit of rewiring before. I've had to replace the cable from the distribution board (DB) to the cooker because we're moving the cooker to another location and the existing cable was not in the right place and was too short (by about 1m). I've replaced all the cabling using 2.5mm H05RR-F cable (this is a high spec rubberised cable, with 5 cores, strangely with two black cores, 1 brown, 1 blue and 1 green/yellow - no grey as I expected for 3 phase). The cable I replaced was exactly the same as this one with two blacks, a brown, a blue and a green/yellow. Again no grey.
Anyway, on closer inspection - at the distribution board - I can see three live cables coming (all brown with no obvious markings) coming in from the supplier, each fitted to screw in 40A fuses. There's a big fat earth cable as well doing the obvious thing. I'm assuming the 3 x brown cables are L1, L2, L3 but which one is which is not obvious. Each phase then goes into a 3P+N RCD, with the phases splitting out to power various circuits around the house via MCBs. The electricians who originally did the work, wired a connection into three individual MCBs (via type B 16A). , each of which then goes off to the cooker (with blue(N) and green/yellow (E) connecting to the appropriate DB connection blocks/strips). Ok, so far so good, easy to understand.
I've already connected this new installation and checked all the voltages at the connection points and the new cable is all OK and as expected. But now I've hit a bit of a snag. I took the back off the cooker and I can see three connections at the back for L1, L2, L3 (and the usual PE (N) and Earth). Unfortunately, I don't know which phase is which from the DB as there are no labels on the cables - they are all the same there (brown).
I am wondering if I need to be concerned about which phase I connect to which terminal since they are all carrying 230V with respect to N and 400V with respect to each other. My primary concern is if there any safety issues from connecting the phases in potentially the wrong order (e.g. could something get 400V instead of 230V?).
Any ideas on whether I should be concered about which phase goes where?
Anyway, on closer inspection - at the distribution board - I can see three live cables coming (all brown with no obvious markings) coming in from the supplier, each fitted to screw in 40A fuses. There's a big fat earth cable as well doing the obvious thing. I'm assuming the 3 x brown cables are L1, L2, L3 but which one is which is not obvious. Each phase then goes into a 3P+N RCD, with the phases splitting out to power various circuits around the house via MCBs. The electricians who originally did the work, wired a connection into three individual MCBs (via type B 16A). , each of which then goes off to the cooker (with blue(N) and green/yellow (E) connecting to the appropriate DB connection blocks/strips). Ok, so far so good, easy to understand.
I've already connected this new installation and checked all the voltages at the connection points and the new cable is all OK and as expected. But now I've hit a bit of a snag. I took the back off the cooker and I can see three connections at the back for L1, L2, L3 (and the usual PE (N) and Earth). Unfortunately, I don't know which phase is which from the DB as there are no labels on the cables - they are all the same there (brown).
I am wondering if I need to be concerned about which phase I connect to which terminal since they are all carrying 230V with respect to N and 400V with respect to each other. My primary concern is if there any safety issues from connecting the phases in potentially the wrong order (e.g. could something get 400V instead of 230V?).
Any ideas on whether I should be concered about which phase goes where?
