1 or 2 dedicated 120VAC circuits for my CNC?

More
13 Dec 2022 05:30 #259298 by Sray69
Quick question:
Can I hardwire the 30A line to my cabinet and just have it plug into the wall with a 30A plug/outlet? Or should I have the cord plug into the cabinet via a inlet/outlet as well? I was just planning to go the hard wire route to save money and one less connection to deal with.

Sorry if this is a dumb question. Just checking in case there is a specific reason not to hard wire that I may not have thought of.

Thanks

Please Log in or Create an account to join the conversation.

More
13 Dec 2022 06:01 #259299 by spumco
Hardwire to the disconnect switch inside your cabinet (use a cable gland through the housing panel) and a plug on the other end.

Less to go wrong.
The following user(s) said Thank You: Sray69

Please Log in or Create an account to join the conversation.

More
13 Dec 2022 13:03 #259311 by andypugh
Wire to a receptacle on the cabinet, makes it easier to move the machine or replace the cable if it gets damaged.

:-)

Both have pro's and cons. I can't even remember how my machines are wired. I think that that are hard-wired and that's generally how conventional manual machines were wired. Often a gland into a terminal box. The problem with having a receptacle on the machine is that the machine might be shipped to a country where the matching plug is not available.

...
Just had a look, both my current machines are hard-wired at the machine end. I have never had cause to wish it was otherwise.
The following user(s) said Thank You: Sray69

Please Log in or Create an account to join the conversation.

More
13 Dec 2022 16:55 #259331 by Sray69

Hardwire to the disconnect switch inside your cabinet (use a cable gland through the housing panel) and a plug on the other end.

Less to go wrong.

That is exactly what I was thinking. Thanks

andypugh Wrote:
Wire to a receptacle on the cabinet, makes it easier to move the machine or replace the cable if it gets damaged.

My plan is to have the cable come out the cabinet through a gland and then to 30A plug/outlet on the wall. The cord will only be a few feet. So to move the machine I just unplug from the wall and move it. I do see your point about if the cord gets damaged. I don't see that happening in its current location as it is against the wall that it is plugged into. There will not be any cord laying on the ground or where it could get damaged. 

Thanks guys!

Please Log in or Create an account to join the conversation.

More
03 Jan 2023 20:38 #260869 by Sray69
I have a couple questions. As I am wiring my panel I am finding that I mis-calculated some of my circuits (wire gauge/amp/breakers, etc). I have corrected them along the way. But I have a couple things I would like to make sure I understand correctly.

1. I am feeding my cabinet with 30A 120V. I then distribute that to multiple breakers. If one of the breakers is 10A, I assume the wire feeding the breaker would need to handle the 30 Amps coming in? And then after the breaker it would need to handle 10 Amps?

2. My Router circuit (feeding an outlet for the router mounted on the side of the cabinet) is a 10A circuit because the Dewalt DWP611 is rated at 7A. I am trying to determine what wire I can use to feed the outlet. I have a 18AWG stranded silicone wire that is rated 7A Carrying Current and 20A Instantaneous Current. Would that be safe for this circuit? I usually like to have a little extra room. Especially when the router will be running for lengthy periods of time. The length of the wires in question are very short. Maybe a foot or two tops.

I know these may be dumb questions but I just like to be safe and make sure I am understanding what I am doing and why.

Thanks

Please Log in or Create an account to join the conversation.

More
03 Jan 2023 22:53 #260877 by andypugh
There are “Ampacity calculators” online. Maybe try to find one that includes wire length.
The following user(s) said Thank You: Sray69

Please Log in or Create an account to join the conversation.

More
04 Jan 2023 01:01 #260887 by spumco
1. Correct.  if you look way back in the thread I provided some suggestions for the 30A run to the main CB (based on your 120v system.)

2. Ditto to Andy's response.  To expand - most "NEC" wire ampacity charts don't include anything smaller than 18awg or the (more common now) 105c insulation, but you can find them if you look.

Don't forget that the standard ampacity chart is for single conductors, or up to 3 conductors in an appropriately-sized raceway (conduit).  Portable power cord (SOOW/SJOOW) has different, usually lower, ratings for the same AWG conductor.  If you're using a cut-up extension cord or SJOOW to go from the wall to the machine you'll need to search for portable power cord ampacity chart.

 
The following user(s) said Thank You: Sray69

Please Log in or Create an account to join the conversation.

More
04 Jan 2023 15:56 #260932 by Sray69
Does this image look correct? Mainly the wires between the TB's and the CB's and then the wires after the CB's. 

 

I am using mostly high strand, tinned copper, silicone wires (200c insulation) for all my cabinet wiring. They are rated at 600V. But the problem is that it is hard to find any charts that have amp ratings for these type of wires. Plus if you search for Amp charts you will find that most of them are completely different from each other. It has been challenging for sure. And unfortunately Amp ratings are not always listed in the specs. Because of this I try to give myself some extra room in the ratings. Hence the reason I asked about the 7A wire for a router circuit that will draw 7A. I ordered some 14AWG for that circuit yesterday so I should be OK now.
Attachments:

Please Log in or Create an account to join the conversation.

More
04 Jan 2023 18:28 #260943 by spumco
  • The conductors between the distribution block and branch circuit breakers can be sized to match that branch circuit.
  • Make sure your distribution block assembly ( blocks & jumpers) can handle the max system amps.
  • According to NEC/NFPA70 (2017), assuming there's no conductor length ampacity reduction
    • your 3A & 10A branch circuits both could use 18awg
    • Your 20A branch can use 14
    • The feeder from the main CB to the distribution block can be 12awg, as can the line-in (unless you're using SJOOW from the wall)
    • There's no harm in increasing conductor size over the minimum in the tables - only your wallet hurts and the wires are harder to work with.  i.e. - If you're wiring up a bunch of 16awg, and need some 18awg in a few little branches... consider using the 16awg instead so you're not buying/stocking a huge assortment of sizes.
  • Based on the above - and after review of wire lengths & so forth - I'd personally run 12awg everywhere and 18awg on the two smaller branch circuits.  Two wire sizes cuts down on the hidden work (multiple ferrule sizes, connectors, label sizes, etc.).
  • Badger Wire has a chart that goes up to 250c insulation for specialty wires, but I'm not sure of their sources as they're about 5% higher than NEC/NFPA70.
The following user(s) said Thank You: Sray69

Please Log in or Create an account to join the conversation.

More
05 Jan 2023 18:15 - 05 Jan 2023 18:33 #261016 by Sray69
Thanks for the info. I did notice that the ratings on Badgers chart are slightly more than the ratings I found for some of my wire. I kinda wonder if the difference has to do with the ambient temperature that each manufacturer uses as their base? I am not real sure what ambient temperature to use? Badger uses 40C.

I actually started with kind of the same plan to use 12awg and 18awg for most but then I started running into issues with the 12awg not fitting into some terminals. And based on my research of the wire I was using it seemed like 18awg was not big enough. But I didn't really find any concrete numbers that I felt confident in. So I ordered some 14awg to kind of fill the gap.

How much does strand count affect amperage rating? Or does it?
Also how does voltage affect the amp rating?

Thanks
Last edit: 05 Jan 2023 18:33 by Sray69.

Please Log in or Create an account to join the conversation.

Moderators: cncbasher
Time to create page: 0.149 seconds
Powered by Kunena Forum