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Cable length questions

Posted: Tue May 12, 2020 3:19 am
by Fat Freddy's Cat
Hi there folks

Couple of I hope easy questions

I want to keep my drivers in a seperate room to my work area.

I will only need to run cable an absolute maximum of 8 metres (25ft)

Two types of cable

1. Power output from my MW320H-C1400B @ 200W to 4xQB288 and MW240-C1750B @ 210W to 6xQB120
2. Potentiometer cable from above also.

The lights themselves are wired with 18AWG solid cable - and on a short run this is also used for both power and potentiometer connections (each being about 5 feet max)

Am I ok to run the same cable up to 25 feet? Or should I be looking for something thicker? I'm guessing yes with the potentiometer as I assume there is fuck all current passing through it - but with the power line do I need to upgrade to thicker/shielded cable?

Thanks for any advice.

Re: Cable length questions

Posted: Tue May 12, 2020 4:47 am
by Shimbob
If I tell you, will you promise not to shit in my shoes? :)

Re: Cable length questions

Posted: Tue May 12, 2020 4:57 am
by Shimbob
Check out a Voltage drop calculator. Nothing wrong with 25' of 17AWG, which is what the MW320 has.
You're lucky that your voltage is already pretty high, as higher voltages and lower amps tolerate longer wire runs better than lower volts & high amps.

Re: Cable length questions

Posted: Tue May 12, 2020 9:04 am
by Fat Freddy's Cat
Found this https://www.solar-wind.co.uk/info/dc-ca ... calculator

It jumps at the 4 meter mark - am I right to assume it would be a gradual drop rather than a defined one?

I totally won't shit in your shoes.

Re: Cable length questions

Posted: Tue May 12, 2020 4:35 pm
by Shimbob
Voltage drop is constant per unit length of wire and proportional to the length of the wire, ie there shouldn't be any change in rate of drop over length.

I think anything that at least matches the 17awg out of the driver or larger size will do fine. I run 10awg because the spool was only a couple bucks more than 14awg.