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Is it acceptable to use a spare core in a 4 core armoured cable to carry 12volts DC when other cores in the same cable are carrying AC mains?
Discuss AC mains and low voltage DC in same cable? in the UK Electrical Forum area at ElectriciansForums.net
How will you get induced voltage on the dc circuit if the cores are insulated to the highest voltage present i.e. 230volts?You will also have to take into account harmonic effects from the AC and quite possibly induced voltage on the DC circuit.
How will you get induced voltage on the dc circuit if the cores are insulated to the highest voltage present i.e. 230volts?
Band 1 (ELV) and Band 11 (LV) circuits can be contained in the same cable where each conductor of a multicore cable is insulated to the highest voltage present i.e the Band 11 voltageInsulation rating does not effect induction, however as the OP is discussing a multicore cable then to comply like you and others have put it has to have a earthed screening which will block any chance of an induced current between the 2 categories as we must assume AC mains means 230/400 volt ac against his 12v DC, as for harmonics, if you suspect this as an issue then the wiring and preventative measures in total needs careful design.
Band 1 (ELV) and Band 11 (LV) circuits can be contained in the same cable where each conductor of a multicore cable is insulated to the highest voltage present i.e the Band 11 voltage
As stated in option 2 given in bs 7671
Is the ELV Ethernet insulation rated the same as 230 v cables?Is it permissible to run ELV Ethernet over LV 230V ac cables?
yep agreed I've re read it over and it does say system , I even wrote the dam thing on the thread.As I interpret it that is for the same wiring system, they have made a specific regulation exemption No' 6 for multicore cable as that does not fall under the term same wiring system due to the fact its a cable and not multiple cables or cores in a wiring system.
See further replies in the thread pal.This is interesting as I come across this a lot and never use the cable for ELV as worry about interference.......so you reckon there can't be an induced voltage due to the insulation Ian? Surely that can't be the case as you can get induced voltage from LV to LV? Or am I getting it wrong? Would be handy to be able to use the same cable for ELV and LV.
I would assume so, as the conductors used for the Ethernet are the ones already being used for the 230V.Is the ELV Ethernet insulation rated the same as 230 v cables?
Then no
I would assume so, as the conductors used for the Ethernet are the ones already being used for the 230V.
How will you get induced voltage on the dc circuit if the cores are insulated to the highest voltage present i.e. 230volts?
Just wondering why there has to be screening between cores in some multicore cables, when it's possible to use the same cores for both ac and dc?
As I interpret it that is for the same wiring system, they have made a specific regulation exemption No' 6 for multicore cable as that does not fall under the term same wiring system due to the fact its a cable and not multiple cables or cores in a wiring system.
It mentions wiring systems so if I read it again to me it's saying that if I have singles in conduit I can run band 1 and band 2 in the same conduit wiring system if each conductor is insulated to the highest voltage present i.e. 230 v.Hi - I'm going to stick my neck for purposes of a good discussion, and not saying I'd like to run 12V in the same multicore cable as 400V .
Reg 528.1, intro says no mixing Band 1 and Band 2 unless one of the 6 exemptions applies. Understood. I take it on board about the 6th method, but if we read it as a specific method for multicore cable, what about the 2nd method? Where it also says "each conductor of a multicore cable". Doesn't that mean there are 2 exemption methods for multicore cable? I haven't spotted why 6 should be read as separate from a wiring system but 2 should not
It's been a good discussion tho in which the forum is all about.Well in honesty I did say IMHO, yes I missed that part in point II @Wilko - and agree with both you and @Ian1981 on that.
I work on machinery to differing reg's and the reason for my take on this is safety under fault conditions, I see a big flaw in this regulation and I may raise it with the IET myself, but it would seem simply having the insulation value to the highest conductor would suffice, I would still consider the implications of the LV crossing over to the ELV and the potential risks associated with it if it were to occur, fusing alone isn't always a sufficient, like I said I said before, if DC is generated and isolated from the LV side in its generation then this could potentially create a accident waiting to happen.
Yes I agree, the ELV may be very basic ("it's only 12V...") and probably shouldn't be in the same jb containment (?) which would likely happen if it was within a multicore swa. Perhaps for ELV control signals for a machine (that's being powered by the other cores of the swa, say) then it could be ok per 2nd option ?... I would still consider the implications of the LV crossing over to the ELV and the potential risks associated with it if it were to occur, fusing alone isn't always a sufficient, like I said I said before, if DC is generated and isolated from the LV side in its generation then this could potentially create a accident waiting to happen.
Over the years, I have been tasked with wiring a few Dali type lighting systems using 5 or 7 core cables.
3 or 4 cores for power and 2 cores for data.
The power is LV ac and the data ELV dc.
Cables have been either flex or SWA depending whether they are internal or external.
None of the cables have had internal screening between the LV and ELV.
do you not know what an induced voltage is?How will you get induced voltage on the dc circuit if the cores are insulated to the highest voltage present i.e. 230volts?
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