Power Cable Heating Up.

[B0M0A0K]

Hi.

I have now completed testing and first print with my new Duet3D WiFi board. While all the commissioning test for heated bed and Extruder were as suggested in the guide "Ender 3 Pro and Duet Maestro Guide Part 3: Commissioning" I am a little alarmed at how warm the main power in cable gets. This is most evident when the bed is being powered up to temperature. I can hold the main power cable but it's obvious that its warm.

I have used the original cable that Wanhao used in the control box so would have expected this to be able to handle the load, however, I am aware that as it was inside the box I would not have been able to touch it.

The power cable used appears to be match for 17amp cabling I have used on other projects and is multicore rather than solid. It is fixed at the PSU end with spade connectors and at the Duet3D Wifi end with the supplied ferrules.

The power supply is the original Wanhao Duplicator i3 v2.1 unit as follows;

Sompon
S-250-12
Input: 100-120 AC 60Hz
200-260 AC 50Hz
Output: +12V 20A

Would you expect this cable to get warm while the bed is being powered?

[DocTrucker]

Any identifying marks on the cables?

Many of the cheap machines have been recievng complaints about poor quality cabling and/or connectors.

I'd take it on the chin and replace it with a cable that is known good for the load. It may be that some of the individual cores (right way of describing the individual fibres of wire escapes me at the moment! ) have broken causing a hot spot, or simply it is undersized. OEM software may have even been running heater elements with PWM limits just to save a few pennies on more copper.

[zapta]

In case you are looking for high quality cables, I had had good results with these ones https://www.amazon.com/gp/product/B07588953X . Wire gauge range and very flexible.

[A Former User]

Unclear which cable you're referring to; AC supply to your power supply, or DC supply to the Duet?

In any case, the power supply is 240W, and it shouldn't be an issue without heating the cable at 12v, 110v or 240v.

The issue may not be the cable but the connections, if there are poor contacts it will generate heat and the copper will conduct the heat into the cable.

Regardless of the issue, verify if the whole length of the cable is roughly the same temperature or its hotter at either end.

Determine what current is required and look up the wire needed in the ampacity column here
https://en.wikipedia.org/wiki/American_wire_gauge#Tables_of_AWG_wire_sizes

Beware the outer diameter for cheap/chinese cable can be very misleading, so you need to look at the conductors to be sure unless you're sure the cable is from a serious vendor.

[B0M0A0K]

Replaced the cabling from the PSU to the Main board power connector with good quality AWG12 silicone cables. Tested the heated bed for signs of heating and there was no issue. This one's fixed.