Bus wire size connected to HM | DC 6000

[Pebro]

Hi. Just starting new to Hornby railways and a bit confused about what size wire to use from the HM6000 unit to the bus wire servicing each track circuit. (Also if the bus wire is a different size a suggestion for that too!)

Any help great appreciated

[Chrissaf]

If you scroll further down page 1 of this HM DC forum section, you will see a previous thread titled "Wire size (used on the HM6010)".

This previous thread indicates that the connectors on the HM6010 units are able to accommodate very thick wires.

But just because thick wires are supported, this does not mean that thick wires need to be used.

You need to consider the wire thickness from the point of view of the size of the current that they need to handle. The output of the HM6000 to the TRACK will typically be nearer 500mA max. Thus the wire only needs to support no more than 1 amp which includes a significant safety margin. In wire size terms, this would equate to a 7/0.2mm wire size. 7 strands of 0.2mm wire which is rated at 2 amps. However, if the intention is to implement a BUS distribution system as your post infers, then I would use the 7/0.2mm for the track droppers and slightly thicker wire for the BUS that is going to cover much longer wire runs. For example 16/0.2mm or 24/0.2mm wire. Thus it would be this slightly thicker wire size that would actually terminate on the HM6000, with the smaller 7/0.2mm wires forming short dropper connections to the track pieces.

Wiring from the HM6010 units connected to Solenoid point motors should be thicker as the CDUs inside the HM6010 units will generate brief multi-amp currents. I suggest 32/0.2mm wire for the points.

EDIT: As Rob has reminded me in his later posted reply below. The HM6000 track units come pre-wired, so unless you want to cut off the wires and attach your own, then this wire size question is somewhat academic.

[Pebro]

Hi Cris. Thanks for this helpful guidance. I’ve been looking on line to purchase flex and sometime sqmm is quoted rather than stands / wire thickness

Do your sizes convert as follows

7 x 0.2mm is around 1.5 sqmm

16 x 0.2mm around 3.5 sqmm and

24 x 0.2mm is around 5 sqmm ?

cheers

[Pebro]

Sorry should have added that the layout is the fully extended track mat with two circuits connected to the HM|DC and a separate controller on the turn outs (if that makes sense(?)

[Chrissaf]

The term "Flex" usually indicates sheathed cable such as for example electrical brown and blue wires in a common outer sheath [uK colours].

7/0.2mm 16/0.2mm 24/0.2mm terms mean "Wire" and not Flex.

Search my quoted x/ymm terms and you will get loads of Internet hits.

7/0.2mm wire is far thinner than 1.5 sqmm.

Your 3.5 & 5 sqmm sizes will be extremely thick and too thick for your needs.

Unfortunately there are no documented direct 'x/y mm' to sqmm conversion charts that I can find. There are conversion charts to convert to AWG, so one would have to find conversion charts for 'x/y mm' to AWG and AWG to 'sgmm', but then expect a certain level of conversion error when comparing the converted AWG values.

The other thread I directed you to in my first reply, indicates that 16/0.2 and 24/0.2 wires are also thinner than 1.5 sqmm.

With regard your 5 sqmm size suggestion. Just to put that into perspective, 6 sqmm Twin & Earth cable is typically used in domestic electrical wiring to power Cookers and Instant Shower heaters and typically fused at 30 to 45 amps.

[96RAF]

HM6000 comes ready fitted with a long pair of wires, each with a two prong connector to mate with a standard power track. The module ends of these wire pairs are soldered to the module PCB within the plastic case so unless you want to cut of the wires close to the case and solder on your own cable then the existing wires provided are adequate gauge to handle the power and of sufficient length to reach across a Track-Mat sized layout.

HM6010 is a different kettle of fish and as Chris has stated you connect your own triple wire cables from the ports to your accessory of choice. Power for each module is by way of a standard Hornby 6.3mm x 3.0mm jack.

With regard to gauge - for comparison, if you have any ring main cable laying about that is 2.5mm2 - a relatively hefty wire. Mains Lighting cable is either 1.0 or 1.5mm2 and still quite heavy. OK for fixed bus wires but no use in situations needing flex cable.