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Cable for ELV lighting application

R E Allen

Please can anyone give me advice on cable selection for an ELV (24V) LED lighting tape application?

The tape is the RGB+W type, i.e. 5 conductor, rated at 19.2W/m. I want to install a 5m run, which would amount to 96W and hence draw 4A. For the ELV driver-to-tape connection, the manufacturer supplies 5-core PVC flex to ISO 6722-1:2011 Class B, which is the standard for Road Vehicle wiring, 60 or 600V (60V in this case). This cable has 0.5 sq.mm copper cores (16 x 0.2mm dia), to BS EN 60228:2005, a max operating temp. of 105 deg.C,and a nominal current rating of 11.0A, according to the manufacturer's data sheet.

A quick glance at Table 4F3A tells us that 0.5 sq.mm flexible cable of any temperature rating over 60 deg.C has a current capacity of 3A (AC - for some reason this table doesn't specify DC, anyone know why?) This type of flex would presumably be made to BS 7919, but the copper is still to BS EN 60228, which would suggest to me that the current carrying capacity would be much the same for any cable made using this copper wire, regardless of the cable standard.

I cannot see this cable carrying 11 Amps for a long and happy service life; but my question is this: can I rely on it to carry the 4A in my application, and would it comply with table 52.3 and 715.524.201, which are rather vague?

Many thanks,

Rob

  • 0

    Hi Rob, I believe the cable they are using is Tri Rated Cable hence why its operating temperature is 105 degrees and a 0.5mm cable carries 11 amps. This cable is not listed in BS7671 the closest match would be table 4E1A. How long is the Cable run between the Driver and cable Tape ? 

    Many thanks, 

    Yassir Khalil TMIET 

  • 0

    Also Regulation 715.524.201 Refers to cable and the maximum load and the next section would apply to for example a 4mm minimum if you had a single 4mm cable suspending a light fitting. 

    I imagine that your application will include some form of containment for support and aluminium profile for the LED strip for heat dissipation. therefore the first section applies to you only. 

    also table 52.3 applies, because its 24 volt I believe it comes under control wiring so 0.5mm minimum. 

  • 0

    This type of flex would presumably be made to BS 7919, but the copper is still to BS EN 60228, which would suggest to me that the current carrying capacity would be much the same for any cable made using this copper wire, regardless of the cable standard.

    For most cables, the limiting parameter is the insulation material rather than the conductor. PVC type compounds degrade gradually with heat and time - the hotter a cable is run the shorter its useable lifespan. For fixed wiring we typically expect a cable to last 70+ years - which it does when the conductor temperature is limited to around 70 degrees max (depending on duty cycles etc). For vehicles the expected service life is closer to 10 years - so the conductors can run much hotter and the resulting reduction in lifespan by nearly an order of magnitude is acceptable

       - Andy.

  • 0

    it will be fine with a max load of less than 5A, and the temperature rise will be very modest.

    If the power supply is mains isolating, for example SELV, or PELV, then 60V rated wire will be fine.

    Mike

  • 0 in reply to mapj1

    I agree, if the cable is short between the driver and strip no volt drop it will be fine if not extended. Tri rated is usually rated at 600 volts so all good 

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