Wiring Gauge
June 10, 2015 02:05AM
Hello everyone... Some experienced advice please:

I'm to the point of wiring up all the components on my DIY printer so I'm looking for advice on the various wire gauges. I read through the safety tip section so I don't want to cut corners on the wiring and connectors.

I'm using 120v mains for the aluminum heat bed with a AC/DC SSR controlled by Smoothieboard PID. The fixed heat bed uses insulated 16 ga. nichrome resistance wire that I've tested and I'm satisfied with the performance. I've bought new 14 AWG power plug cords to run from the mains outlet to a 20A GFCI plug mounted on the printer chassis. I will ground the aluminum bed to the GFCI and the power cord to the grounded wall plug.

I have a second 14 AWG power cord to run between the GFCI plug and the SSR, and then a cut section of 14 AWG power cord from the SSR to the bed/controller per a wiring diagram I found for that setup. I plan to run a separate 14 AWG power cord to the 24V PSU for the Smoothieboard.

From there I'm wondering whats the best wiring type and size for the various components being powered off the Smoothieboard? Hot ends; fans; end stops; Nema 23 and 17 motors for the axis and extruders...etc. I'm using separate 20A rocker switches for the heat bed and PSU, so I'm planning to use more 14 AWG power cord for those runs too. Is the 14 AWG sufficient for the uses described?

Your experience is appreciated...I am thankful for this forum and everyone who contributes. Thanks in advance...
Re: Wiring Gauge
June 10, 2015 03:09PM
18AWG or large for the hot end presuming 12V and <= 40 watts leaving a significant safety margin. You could go smaller if you really had to. Pretty much anything for the endstops and fans since they are so low current...I used some old solid cat5 cable for the individual conductors. Motors depend on the current what you can get away with but 22AWG is typical for NEMA 17 sized motors and 18AWG for NEMA 23. You can always go larger, but the larger the AWG the more expensive, heavier, and harder to bend. There would be no advantage to using 14AWG for any of the above, serious overkill.
Re: Wiring Gauge
June 10, 2015 05:28PM
Thanks CDRU... I'm running a 24V PSU and the E3d Cyclops heat cartridge is 24V also. Should that take a lower gauge wire? I have long travel in every axis so will be using some form of cable chain to keep all the wiring tucked away. The 14 AWG power cord appears to have a natural 4" diameter to the loop end, so 16 or 18 AWG bundled wire running in the cable chain should reasonably be less don't you think? Thanks....
Re: Wiring Gauge
June 10, 2015 07:28PM
I had 14ga in wall speaker wire on hand so i used that for all of the 12 stuff, added a 30amp fuse at the start of the 12v run for protection then used cat5e stranded for all of the servo wiring, mainly because i had is on hand.

someone else wired the bed but that seems to be 12ga wire.
Re: Wiring Gauge
June 10, 2015 10:28PM
Hi raptor_demon...thanks for sharing your wiring setup. I like the idea of an inline fuse. My chassis mounted GFCI plug is 20 amp so I'm looking for that to act as my on-board fuse. I'll probably look for some silicone jacketed 18ga for the control circuits since I don't have any wire stock of my own. Thanks...smiling smiley
Re: Wiring Gauge
June 11, 2015 09:41AM
Quote
simspeed
Thanks CDRU... I'm running a 24V PSU and the E3d Cyclops heat cartridge is 24V also. Should that take a lower gauge wire?
The wire gauge you need to used is determined by the amount of current that will be flowing through the wire, not the voltage. Divide the wattage of your heater by the voltage to determine the current it will draw. So if you have a 40W cartridge, it would draw 40W/24V = 1.67 amps. Voltage and current have an inverse relationship when power remains constant. If voltage doubles, current drops in half. So you actually can get away with using a smaller wire (higher gauge) with a higher voltage.


Quote

I have long travel in every axis so will be using some form of cable chain to keep all the wiring tucked away. The 14 AWG power cord appears to have a natural 4" diameter to the loop end, so 16 or 18 AWG bundled wire running in the cable chain should reasonably be less don't you think? Thanks....
Smaller wire will have a smaller bend radius of the same wire type. If they are different wire types (solid vs stranded, different insulation, etc) then it can vary.
Re: Wiring Gauge
June 11, 2015 11:59AM
Thanks for confirming amp drop for higher voltage Cdur... I located a spool of 18/4 control wire on Craigslist that I'm going to check out today. PVC semi-rigid sheathing so I'm not sure how flexible it is...but the price is right if it looks like it will work. The cable will run inside long aluminum extrusions so I ordered some of these connectors for quick disconnects. I like the function....hope they work as good as they look.
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