# Tips for Your Electrical Panels!



## macardoso (Nov 16, 2019)

Hi all!

I am probably an oddball here who really enjoys the process of building electrical panels. I have two CNC mills (Sherline and a G0704) for which I have built several electrical panels over the years. At my day job, I design industrial control panels for some special applications. I often think the electrical side of machines gets overlooked in the hobby realm and I wanted to share some of my experience and tips for building great electrical panels. 

I would love this to be a place for anyone to share their electrical experience and knowledge so please chime in if you have something to share!

-Mike


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## macardoso (Nov 16, 2019)

Tip #1: Buy a big enclosure

OK, before we even go there… buy a real electrical enclosure. I often see people trying to build electrical enclosures out of wooden boxes, welded sheet metal, Rubbermaid tubs, etc. Unfortunately, it is really hard to make a professional looking panel without a good canvas on which to build. I would recommend Automation Direct or eBay for enclosures, but if you are buying used, really try to get one without holes drilled in it (and yes, I know they’re expensive). Second, buy a big enclosure. Whatever size you think you need is going to be way too small – get one twice the size. When I bought my 24x36 enclosure for my G0704, I thought there would be absolutely no way I could ever fill it. I figured I could add new projects in the extra space, however now the box is 100% capacity without any extra projects. It is crazy how much room you really need and how awful it is when you realize you have run out of space.




Picture above is of my current CNC control panel on my G0704.


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## macardoso (Nov 16, 2019)

Tip #2: Get a subpanel for your enclosure

This is an easy one. Most real electrical enclosures will have threaded studs inside the box to support a subpanel. This allows you to build your design on a bench before attaching it inside the enclosure. It also means you don’t need to put holes in the outside of your fancy new enclosure to mount your parts. You should really aim to do as much wiring of the subpanel outside of the enclosure as possible.


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## macardoso (Nov 16, 2019)

Tip #3: Plan on your electrical panel to take a long time and a lot of effort

I think that in the machining community (CNC especially) everyone brushes the panel build off until the last minute and almost treats it as an afterthought. Although it doesn’t require much machining, there is a *lot* of work that goes into an electrical panel. Make it fun for yourself and plan on it being a major step in whatever you are building.


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## macardoso (Nov 16, 2019)

Tip #4: Design your enclosure ahead of time

At work we spend months designing our panels in CAD before we ever start to have them built. At home this is unrealistic, however I try my best to make sure I have everything planned out before I buy the enclosure or start wiring. Draw all your circuits out, make sure you know every component you will need, how many terminal blocks, what kind of wire, etc. Make sure you follow the installation instructions for your components to give them adequate room for ventilation. My most recent and most complicated home-built panel was modeled in Autodesk Inventor before I bought anything. This allowed me to drill all the mounting holes directly from the dimensions on the model (and everything fit perfectly!).




CAD design of my panel.


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## brino (Nov 16, 2019)

Great start to what should be a very interesting thread. Thanks!

I am watching........


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## macardoso (Nov 16, 2019)

Tip #5: Rivet nuts!
I used to mount my components to my subpanel with screws and locknuts on the rear of the panel. I quickly learned that this was not wise when I had to remove the entire subpanel to replace a single dead stepper drive. In my most recent panel, I installed a rivet nut for every hole which used a #8 or larger screw and tapped the subpanel for the smaller screws. Rivet nuts install in a similar way to pop rivets, but give you a threaded insert permanently mounted to the subpanel. This means everything screws in from the front and you don’t need any nuts on the back. I think I spent $30 for a cheap rivet nut tool and a few bags of nuts. Worth every penny.


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## macardoso (Nov 16, 2019)

Tip #6: Circuit Protection
Circuit protection is absolutely required by electrical code and for good reason. If something goes wrong in your panel, like a short or a failed component, the circuit protection will prevent damage to your equipment or a fire. I typically recommend DIN rail mounted circuit breakers for most applications; however, fuses are good for low current protection, very high current applications, or where space is a concern. You should size your breakers for just above the max load that branch of the circuit will see, or better yet, follow NEC guidelines for breaker sizing! Please don’t rely on your home breaker panel to protect your equipment unless you plan on running 12 AWG wire to *every* connection in your panel. Even then, just don’t!



			https://www.usawire-cable.com/pdfs/NEC%20AMPACITIES.pdf
		










						1489-M Thermal-magnetic Circuit Breakers  | Allen-Bradley
					

These circuit breakers are ideal for extreme ambient conditions, feature fast breaking time, and superior shock and vibration resistance.




					ab.rockwellautomation.com


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## macardoso (Nov 16, 2019)

Tip #7: Use the right wire

While you can certainly wire your panel with any kind of wire (assuming it meets your ampacity needs), your enjoyment of the process will a lot better if you use good quality stranded hookup wire. For almost all of my panels and some of those I do at work I use MTW (Machine Tool Wire) for my hookups. Solid core wire often used in homes will never lay nicely in your panel and is hard to make terminate cleanly.






						Insulation Type - MTW | Wiring Solutions | Products | AutomationDirect
					

Insulation Type - MTW from AutomationDirect, the best value in industrial automation - low prices, fast shipping, and free award-winning service.



					www.automationdirect.com


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## macardoso (Nov 16, 2019)

Tip #8: Ferrules and Crimpers
Get yourself a set of wire ferrules and crimpers. Seriously, this one is huge. Wire ferrules crimp on the ends of your wires and prevent the loose strands of wire from fraying. They are permanently and securely installed by a crimping tool. The professional tools are quite expensive (~$300) but I use a set at home that cost me $20 on ebay and came with a ton of ferrules. The off brand crimpers are perfectly fine to use, but I think that Panduit ferrules are significantly better than the cheap ones. I wouldn’t ever want to do a panel without ferrules on my wires.

Link Here

I have no affiliation with that link, nor have I bought those exact ones, but that is the kind of kit you want to look for. There are lots of styles of ferrule crimpers, however I prefer the 4 jaw style.


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## macardoso (Nov 16, 2019)

Tip #9: Wire Duct

When you are planning you panel, you should consider leaving room for wire duct. This is a plastic trough with fingers that allow you to bring your wires into a “highway” which runs between your components. Who cares if it gets messy since you will be snapping a clean looking cover on it? My source is AutomationDirect.

https://www.automationdirect.com/adc/shopping/catalog/wiring_solutions/wire_duct_-a-_accessories


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## macardoso (Nov 16, 2019)

Tip #10: Wire labels

Placing labels wire your wire number at each end of a wire connection will help you keep track of your connections and is essential in troubleshooting later on if needed. I use Brady adhesive pre-printed labels at home and Panduit printable heat shrink labels at work.

https://www.bradyid.com/en-us/product/wm-1-10-pk

https://www.ebay.com/itm/Industrial...286684?hash=item341537ef5c:g:arIAAOSwuDFcXPsR


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## macardoso (Nov 16, 2019)

Tip #11: DIN Rail and Terminal Blocks

The automation industry has standardized on the 35mm DIN rail for mounting electrical components. From terminal blocks to network switches, you can find almost anything designed to snap on these rails (similar to Uni-Strut). I recommend sticking with these kinds of components in your design since they are easy to install and remove, and they are typically designed to be as narrow as possible to save precious panel space.

I also strongly recommend using terminal blocks for your panel internal connection, especially where you intend to make connections to field devices. These can be had from AutomationDirect for as little as $0.20 each and give you a clean, centrally located point to land your wires. Please don’t ever use those “ice-cubes”, wire nuts, or God-forbid solder your connections.


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## mikey (Nov 16, 2019)

Excellent series of tips, Macardoso! Thank you so much for sharing. Electrical is my primary weakness and the more I learn the better and safer things will get.


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## PHPaul (Nov 16, 2019)

Ooooooooo....

I was an electronics tech in the Navy for 22 years, and have worked around electronic/electrical/electro-mechanical equipment pretty much all my working life.  

My last really technical job was working in a fish cannery with a ton of PLC-controlled equipment, some of it built in-house for a specific task.  I had the pleasure of building and/or rebuilding a few panels  and I REALLY enjoyed the process.  I used every tip you listed except the riv-nuts and would have used them as well if I could have gotten management to spring for the supplies.  Throw in some hydraulic and pneumatic control interfaces and it's about as much fun as you can have and get paid for it!

Yeah, I know, I'm a little strange...


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## Superburban (Nov 16, 2019)

Lots of new info, in a great post, keep it up. 

Thanks.


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## Packard V8 (Nov 16, 2019)

Wish you lived next door and had an occasional taste for home distilled corn squeezins.  Everyone would come out happier.

We have a machine shop at the end of the road where 3-phase can't be had.  As a result, we have a lash-up of three home-built 5hp rotary converters, a couple of VFDs and two maxed out 200-amp service panels.  That everything electrical works is evidence we try diligently, but it ain't pretty.

jack vines

BTW, since we have a couple of experts here, what are the options for feeding multiple panels from one incoming line?  Right now, we're feeding a 50-amp sub-panel with four circuit breakers off a 50-amp breaker in one of the 200-amp panels.  What would the proper junction box look like to take the incoming 220-volt line feed off the transformer and split it into separate lines to four separate panels; two 200-amp and two 50-amp?  Just seems silly to waste panel space and seems even sillier to feed a breaker from a breaker.

j.v.


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## macardoso (Nov 16, 2019)

Packard V8 said:


> Wish you lived next door and had an occasional taste for home distilled corn squeezins. Everyone would come out happier.



Well now that sounds fun! Too bad you're a little more than a short hike away!



Packard V8 said:


> BTW, since we have a couple of experts here, what are the options for feeding multiple panels from one incoming line? Right now, we're feeding a 50-amp sub-panel with four circuit breakers off a 50-amp breaker in one of the 200-amp panels. What would the proper junction box look like to take the incoming 220-volt line feed off the transformer and split it into separate lines to four separate panels; two 200-amp and two 50-amp? Just seems silly to waste panel space and seems even sillier to feed a breaker from a breaker.



I will start with a disclaimer that I am not an electrician and I am not an expert on home electrical code. With that said, you'd definitely want to have one main breaker for the incoming feed (200A) which would distribute out to smaller breakers in that main panel. You would install a breaker in that panel which would be large enough to cover the panel you wish to distribute out to. You would then run wires from that distribution breaker out to your other panel. I have a feeling this is how it is done since your main breaker plugs into the big copper bus rails in the breaker box.

In industry, it is not unusual to have several large loads needing to be powered by one utility. This would be done by installing one large set of fuses (or a breaker) at the utility entrance to the panel and using the NEC tap rule to connect multiple smaller breakers (sized for each individual load) off of the main breaker. These are usually sized or timed to make sure they trip in the correct sequence (smallest breaker first). Real electrical panels often have many layers (branches) of circuit protection.


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## macardoso (Nov 16, 2019)

Tip #12: Cable Entry

Your electrical panel is going to need a way to get wires into and out of the enclosure. For power wiring and short cables which are easy to disconnect at the other end, I recommend using cable glands (cord grips) these are water tight bulkhead connections which mount in a round hole. When you are connecting to long cables or ones that would be easiest to disconnect at your panel, I recommend looking at connectors. My personal favorite are M12 bulkheads. These take up very little space on the side of your panel and come in 4 and 5 pin (also 7, 12, 22, and more) flavors. AutomationDirect seems to have the best price on these. They screw together for a very secure and water tight connection.




https://www.automationdirect.com/ad...ns/micro_(m12)_receptacles/7231-13541-9710050




For ethernet cables, USB, and similar pluggable media, look on eBay for bulkhead connectors that mount in a round hole. This way you can use a UniBit or step drill to cut it out.




If you need to make a *lot* of I/O connections and want a super robust connector (and have very deep pockets), look at MIL-SPEC-D38999 TVIII connectors from Amphenol and others. They are kinda crazy on price but I have never felt quality quite like these.


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## macardoso (Nov 16, 2019)

Tip #13: Disconnect Switch and Operators

It is nice to have a power disconnect switch mounted to the door of your enclosure. AutomationDirect sells some rather inexpensive options for this. These usually have a switch body mounted on the subpanel, a handle on the door, and a bar that connects them. These lock the door closed when the power is on, but can usually be defeated. These are my favorite for home use:

https://www.automationdirect.com/ad.../socomec_ul_508_rated_non-fusible_disconnects

Be warned... It can be a bit tricky to line up the handle on the door so that it catches the bar correctly. Be careful installing it or risk ruining your enclosure (personal experiences here guys ). These should always go on the edge of the door opposite the hinge.


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## macardoso (Nov 16, 2019)

Tip #14: Schematics and Spare Parts in your enclosure

When you are done building, place a bag with all the things you will need to troubleshoot or repair your electrical panel. This should include a couple of spare terminal blocks, terminal screwdriver, fuses, jumpers, spare lights, replaceable relays, etc. You might also want to print out your schematics and place them in a large plastic bag as well. This will be a life saver when you need to fix something far in the future.

AutoCAD Electrical is available for free 3-year educational licenses from Autodesk. Bit of a learning curve but a very powerful and capable program.


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## macardoso (Nov 16, 2019)

Tip #15: Grounding, Bonding, and EMI

You should really pay attention to grounding your electronics and separating noisy wiring (AC power, Stepper motor outputs, VFD outputs, large relays, etc.) from your clean signals (I/O, encoders, DC power, etc.). Use shielded cable where necessary/possible, and give high frequency noise a low impedance path back to ground. I could write an entire paper on this topic, but if you’re interested, there are lots of good references online.




Troubleshooting electrical noise coming from servo drives in my latest panel design. Pain in the


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## Boswell (Nov 16, 2019)

Great Stuff Marcadoso.   Few things are more frustrating that trying to troubleshoot a problem in a panel that looks like spaghetti with no labels or standards. It can take hours even days to find an fix an issue that could have been resolved in minutes if a little care had been taken to follow standards and proper labeling such as what Marcadoso has outlined.


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## MozamPete (Nov 17, 2019)

Tip #12b: Cable Entry 
On cables coming into the panel always leave enough length to to route it nicely to the furthest point in the panel, even if initially it is just going to be terminated close to where the cable comes in.  Excess can be stored neatly in the wire duct and it allows for future modification.


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## Bi11Hudson (Nov 17, 2019)

An old geezer's two cents worth, probably a quarter now-a-days. 

A rule of thumb I learned way back in the sixties (1968) was for a new cable entering a panel, leave the length from the entry point to the farthest corner and then to the diagonally opposite corner. It's easy to cut off the excess, but adding a couple of inches is a real PITA. Wire is cheap, *avoid splices at all costs*. If it's too short. land on a terminal strip and use new wire from there. Once lost a half a day's production chasing one such in a panel for a casting machine, at $1000/*minute* production in the '70's.

Panduit is beautiful stuff. I originally learned to tie with lacing twine, and then with small Ty-Raps. Then Panduit came along and things took a (or two or three) giant step(s) forward. 

Having learned my craft on ships, as well as industry, I have an aversion to "crimped" connections. My preference for stranded wire getting a loose "whisker" is to strip and then immediately solder the end. Not to anything, just converting stranded to solid for the last half inch. I can't say it has paid off, but I have seen crimps get corroded and come loose after a couple of years. Wire landed under a screw gets an inch or better tinned. Otherwise, avoid soldered connections.

Every electrical man has his own preferences that developed from varying experiences. Each is different and none is really "better" than the other. The above are a sampling of my experiences only.

.


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## PHPaul (Nov 17, 2019)

That's a few more pins than I've done, but my electronics experience in the Navy was primarily communications, and I've terminated more 56 pair cables to that sort of connector than I care to think about.    Some were crimp on pins, some were solder cup type.   You learned early on in the process to triple check the color codes to be sure the right wire was going to the right pin...


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## uncle harry (Nov 18, 2019)

Bi11Hudson said:


> An old geezer's two cents worth, probably a quarter now-a-days.
> 
> A rule of thumb I learned way back in the sixties (1968) was for a new cable entering a panel, leave the length from the entry point to the farthest corner and then to the diagonally opposite corner. It's easy to cut off the excess, but adding a couple of inches is a real PITA. Wire is cheap, *avoid splices at all costs*. If it's too short. land on a terminal strip and use new wire from there. Once lost a half a day's production chasing one such in a panel for a casting machine, at $1000/*minute* production in the '70's.
> 
> ...


Regarding soldering, NFPA79  states that wires shall not be soldered unless the device to be connected requires it. NFPA79 applies to machine tool wiring requirements.


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## macardoso (Nov 18, 2019)

PHPaul said:


> That's a few more pins than I've done, but my electronics experience in the Navy was primarily communications, and I've terminated more 56 pair cables to that sort of connector than I care to think about. Some were crimp on pins, some were solder cup type. You learned early on in the process to triple check the color codes to be sure the right wire was going to the right pin...



Ugh, that doesn't sound fun at all. I just did a few dozen of these. That being said, they just work! No fuss or anything.


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## macardoso (Nov 18, 2019)

uncle harry said:


> Regarding soldering, NFPA79 states that wires shall not be soldered unless the device to be connected requires it. NFPA79 applies to machine tool wiring requirements.



Huh... Never knew that code existed but great to know!

13.1.1.5 Soldered connections shall only be permitted where terminals are provided that are identified for soldering.


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## mksj (Nov 18, 2019)

Nice review. Pretty much follow most of what you have outlined, I prefer to use spades with terminal blocks in some applications. Typically I just tap the back plate for mounting, reduces cost and something like a VFD/braking resistor will sit flush against a metal surface which aids in heat dissipation. Would use threaded studs for heavier mounts like transformers/chokes, etc. Shielding and grounding can be a big problem, and often is not as straight forward as one thinks. Keep your signaling wire away from AC and higher voltage wiring. Read the manuals and follow what they recommend as a starting point. Test your systems thoroughly, I always build in safety redundancy in my designs when possible.

Soldering of wire is not recommended for terminal connections and crimps, it will cold flow and loosen. In addition it is associated with breakage due too fatigue in wiring that experiences vibration/repeated movement. I recommend using higher end crimps (like T&B) that are nylon insulated and have a double wall crimp typically of copper alloy which fuse with the wire. I have tried pullout tests and the wire breaks before it can be pulled out. There are a few exceptions to soldering seen in the marine environment where salt will get into crimps and eventually corrode the wires. What I read a while back  was you always crimp the wire first and then flow the solder at the tip of the crimp, being careful not to flow too much solder so it does not wick down the wire. This is outline in certain cost guard guidance's.  An alternative is using crimps (like 3M) that have fusible shrink tube insulator, this seals the wire completely after crimping. I cannot emphasize enough the importance of a good crimper with the proper die for the type of crimp used. I use to have all kinds of poor contacts until I upgraded to better crimps and a decent crimper that ran around $70.


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## macardoso (Nov 18, 2019)

mksj said:


> I cannot emphasize enough the importance of a good crimper with the proper die for the type of crimp used. I use to have all kinds of poor contacts until I upgraded to better crimps and a decent crimper that ran around $70.



Agreed! There are hundreds of different crimp style connectors and you definitely need the right tool for your connectors. We use Panduit crimpers at work that go out for yearly calibration. I think they run $300 new. I've never had a bad crimp with my $20 home set, but I would never use them at work.


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## Joeman77 (Nov 18, 2019)

Congrats on some nice looking work! I built panels for several years & agree with about everything you've said, the exception being I've never used (Tip #5) Rivet nuts, not because they're bad, we just tapped the sub-plate & threaded the screws into it.


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## Joeman77 (Nov 18, 2019)

macardoso said:


> Tip #4: Design your enclosure ahead of time
> 
> At work we spend months designing our panels in CAD before we ever start to have them built. At home this is unrealistic, however I try my best to make sure I have everything planned out before I buy the enclosure or start wiring. Draw all your circuits out, make sure you know every component you will need, how many terminal blocks, what kind of wire, etc. Make sure you follow the installation instructions for your components to give them adequate room for ventilation. My most recent and most complicated home-built panel was modeled in Autodesk Inventor before I bought anything. This allowed me to drill all the mounting holes directly from the dimensions on the model (and everything fit perfectly!).
> 
> CAD design of my panel.



I always tried to add about 25% for a few extras or expansion. A bigger panel is a few bucks more, another one is a lot more.


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## uncle harry (Nov 18, 2019)

Joeman77 said:


> Congrats on some nice looking work! I built panels for several years & agree with about everything you've said, the exception being I've never used (Tip #5) Rivet nuts, not because they're bad, we just tapped the sub-plate & threaded the screws into it.



_I might add that for producing threaded holes I_ like to use drill/tap/countersink bits and a clutch adjustable drill motor.


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## PHPaul (Nov 18, 2019)

As far as crimp terminals, I've gone almost exclusively to heat-shrink style vs. the nylon.  More expensive, but far fewer problems, especially in automotive/trailer applications.


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## macardoso (Nov 19, 2019)

Joeman77 said:


> Congrats on some nice looking work! I built panels for several years & agree with about everything you've said, the exception being I've never used (Tip #5) Rivet nuts, not because they're bad, we just tapped the sub-plate & threaded the screws into it.



I should clarify that I only use rivet nuts at home as I have sometimes used thinner aluminum sheet metal to save cost when I buy an enclosure on ebay and it doesn't come with a subpanel. At work we always drill and tap the subpanel or sometimes weld studs to it for heavier devices.  I found the rivet nuts to be really helpful in my current build, however the right way to do it is buy the heavier gauge steel subpanels from your enclosure supplier.


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## macardoso (Nov 19, 2019)

Tip #16:

If you have devices in your control panel that require configuration or have configuration software, copy all the necessary files onto a USB drive and zip tie it to the inside of the cabinet door. That way if you need to change something down the road, you don't need to go hunting for old software or configuration files. This is also great for manuals, purchase orders, or notes to yourself.

-Mike


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## Bi11Hudson (Nov 20, 2019)

uncle harry said:


> Regarding soldering, NFPA79  states that wires shall not be soldered unless the device to be connected requires it. NFPA79 applies to machine tool wiring requirements.



Well, it seems I am a bit behind the times. My copy of the NEC is 1994, by the way. But there are many cases where the NEC (and NFPA) have no say in the way things are done. I have made it my practice to make my installations *safe*, not necessarily code compliant. Yes, there are places where this can make a difference. And remember, codes are *minimum* standards for workmanship anyway.

I will concede that I am in (serious) error here. But I will continue to do things the way I have for near 50 years now. Such as tinning a stranded wire where it fits under a screw head. I do use crimped on lugs on a regular basis. I have hundreds on hand. But when I think it will work better and be safer in the long haul, I will continue to use my own methods. And signing this can be taken as my signature on the subject.

Bill Hudson
.​


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## matthewsx (Nov 20, 2019)

I guess I'm old school to. Tinning stranded wire with good quality solder seems like something I'll continue to do unless someone can explain how it might be a hazard or somehow unreliable. 

Maybe I should look into these crimped lugs though, I use crimps for most other stuff (ABYC Marine Electrical Certified). But, when I have to solder wires into connectors anyway it seems easier to just tin both ends.

1ohn


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## Jeff.64 (Nov 21, 2019)

uncle harry said:


> Regarding soldering, NFPA79  states that wires shall not be soldered unless the device to be connected requires it. NFPA79 applies to machine tool wiring requirements.



The NFPA 79 publication is a great resource.  I purchased the 2007 edition back in 2008 for around $40.  At the time I thought it was a lot to pay for 88 pages.  I just checked and the 2018 edition is $65.50 for 106 pages.  Still expensive for a "one of" project.  If one could borrow a copy, it would be worth while read for anyone building their own panel.


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## Jeff.64 (Nov 21, 2019)

Bi11Hudson said:


> Well, it seems I am a bit behind the times. My copy of the NEC is 1994, by the way. But there are many cases where the NEC (and NFPA) have no say in the way things are done. I have made it my practice to make my installations *safe*, not necessarily code compliant. Yes, there are places where this can make a difference. And remember, codes are *minimum* standards for workmanship anyway.
> 
> I will concede that I am in (serious) error here. But I will continue to do things the way I have for near 50 years now. Such as tinning a stranded wire where it fits under a screw head. I do use crimped on lugs on a regular basis. I have hundreds on hand. But when I think it will work better and be safer in the long haul, I will continue to use my own methods. And signing this can be taken as my signature on the subject.
> 
> ...



I worked for a company back in the 90's building CNC machines and they had switched to wire ferrules in, at the time, recent history.  Prior to that, the common practice was to tin wires using solder pots when terminating smaller gauge wire in terminal blocks.  The only down side in my experience to using wire ferrules is, that it can sometimes be difficult to terminate two wires in a terminal.  I don't know what the accepted practice is for 2019, but back then you were allowed to terminate up to two wire per side of a terminal block.  I too have not heard of properly tinning a wire prior to termination being problematic.  Since I do not own crimpers and ferrules I would not hesitate to tin a wire prior to termination.


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## Jeff.64 (Nov 21, 2019)

macardoso said:


> I should clarify that I only use rivet nuts at home as I have sometimes used thinner aluminum sheet metal to save cost when I buy an enclosure on ebay and it doesn't come with a subpanel. At work we always drill and tap the subpanel or sometimes weld studs to it for heavier devices.  I found the rivet nuts to be really helpful in my current build, however the right way to do it is buy the heavier gauge steel subpanels from your enclosure supplier.



AutomationDirect is a great source for inexpensive components, I've use them for over 10 years.  As to subpanels, I've always drilled and tapped holes.  I have a project at work coming up and plan on using a perforated subpanel.  Slightly thinner at 14 gauge but they have 0.125" holes on 0.250" spacing.  I think this will make mounting components much easier.






						Perforated Subpanels | Enclosures / Subpanels / Thermal Management / Lighting | Products | AutomationDirect
					

Perforated Subpanels from AutomationDirect, the best value in industrial automation - low prices, fast shipping, and free award-winning service.



					www.automationdirect.com
				




Great idea using rivet nuts for home projects!  Thanks for your well thought out and informative post.  It will be a great resource for first time builders.


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## Jeff.64 (Nov 21, 2019)

mksj said:


> Nice review. Pretty much follow most of what you have outlined, I prefer to use spades with terminal blocks in some applications. Typically I just tap the back plate for mounting, reduces cost and something like a VFD/braking resistor will sit flush against a metal surface which aids in heat dissipation. Would use threaded studs for heavier mounts like transformers/chokes, etc. Shielding and grounding can be a big problem, and often is not as straight forward as one thinks. Keep your signaling wire away from AC and higher voltage wiring. Read the manuals and follow what they recommend as a starting point. Test your systems thoroughly, I always build in safety redundancy in my designs when possible.
> 
> Soldering of wire is not recommended for terminal connections and crimps, it will cold flow and loosen. In addition it is associated with breakage due too fatigue in wiring that experiences vibration/repeated movement. I recommend using higher end crimps (like T&B) that are nylon insulated and have a double wall crimp typically of copper alloy which fuse with the wire. I have tried pullout tests and the wire breaks before it can be pulled out. There are a few exceptions to soldering seen in the marine environment where salt will get into crimps and eventually corrode the wires. What I read a while back  was you always crimp the wire first and then flow the solder at the tip of the crimp, being careful not to flow too much solder so it does not wick down the wire. This is outline in certain cost guard guidance's.  An alternative is using crimps (like 3M) that have fusible shrink tube insulator, this seals the wire completely after crimping. I cannot emphasize enough the importance of a good crimper with the proper die for the type of crimp used. I use to have all kinds of poor contacts until I upgraded to better crimps and a decent crimper that ran around $70.



One of my pet peeves is people using crimpers for non insulated terminals on insulated terminals.  Also, I think it should be illegal to sell vinyl terminals.  Anti-wicking tweezers work great to prevent solder from wicking when soldering crimped, non-insulated terminals.
As far as tinning a wire, if the strands are thinly coated such that the strands look like they're tin plated, the terminal block connection would stand the test of time.  I never had a problem with creep like one would have with aluminum wire as in old house trailers burning down due to aluminum wire creep.  If you have a solder glob after tinning, I can see that creep can occur.  I replied to another post stating that in a home brew scenario, I would not hesitate to properly tin a wire prior to terminating it in a terminal block.  But, while composing this reply I decided to check the "interweb" and found this from the T&B site, 'The problems with tinning wires' which I think all of us "wire tinners" should read.


			https://cdn.thomasnet.com/ccp/00142951/263810.pdf
		

Their example shows a wire with excessive solder.  Maybe they need more wire ferrule sales?
So, I thank you for statements regarding the cold flow and terminal loosening problem.  I guess I'm not too old to change my evil ways


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## macardoso (Nov 21, 2019)

Jeff.64 said:


> The only down side in my experience to using wire ferrules is, that it can sometimes be difficult to terminate two wires in a terminal. I don't know what the accepted practice is for 2019, but back then you were allowed to terminate up to two wire per side of a terminal block.



They make ferrules for that  You can usually get ferrules for each wire size in single and double ferrules. They are also available in multiple lengths so you don't need to trim the ferule after crimping.





Jeff.64 said:


> I too have not heard of properly tinning a wire prior to termination being problematic.



I am not an expert on the matter, but I believe the industry shift away from tinning wires began with the aerospace industry's issues with tin whiskers and creep. Since the alloys used in soldering melt at relatively low temperatures, they can experience creep (cold flow) at room temperatures leading to a decrease in terminal tightness in screw down terminals. Whiskers can also spontaneously grow from solder and form long structures which can short out connections. When the EU passed RoHS restrictions in 2006, most of the world's electronics industry shifted away from leaded solders in order to be allowed to sell their products in the EU. Lead-Free solders are much more likely to form whiskers.









						Whisker (metallurgy) - Wikipedia
					






					en.wikipedia.org
				












						Creep (deformation) - Wikipedia
					






					en.wikipedia.org
				




I think that a tinned wire connection is perfectly fine for nearly all connections, but I never see them done at work or at customer sites. The only exception is when a product comes with tinned flying leads from the manufacturer.


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## Asm109 (Nov 21, 2019)

Motorsports and off shore power boat racers do not tin the wires.  The transition from the solid tinned end and the individual strands is a stress concentration point.  Fatigue failures can lead to DNF.  No Bueno.


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## machPete99 (Nov 21, 2019)

I tend to tin stranded wire, but just do it at the very end of the wire to hold the ends of the strands together. This way you are mostly pure copper under a screw type connection, so should not creep, which can be an issue if you tin the whole thing.

Crimp type screw terminals are probably better, but I still tend to hit them with some solder after crimping, but not so much that it flows under the insulation, which can stiffen things up and cause problems.

I also have one of those square crimpers and the ferrules and they work great for low voltage control connections. I still tend to hit the ends of them with a little solder, just in case.

I am not into the more complex control panels but for simple VFD setups I will go with NEMA rated sealed enclosures and make my own panel from some 1/4" aluminum and drill/tap as needed.

Kudos to the thread authors and contributors as lots of good info here!


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## Cheeseking (Nov 21, 2019)

Asm109 said:


> Motorsports and off shore power boat racers do not tin the wires. The transition from the solid tinned end and the individual strands is a stress concentration point. Fatigue failures can lead to DNF. No Bueno.



X2.


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