Best Practice on tying grounds together
I’m roughing in the wiring to my new shop. I have several 4-position boxes (PVC) which will have a number of 3-way circuits in each. I can count up at least 8 different ground wires between the three home-runs coming into the boxes, plus the 12/3 runs for the three-way switches.
I’m going to tie all the grounds together and pigtail for the grounds to the switches. A big wirenut just doesn’t seem the right way to go….so what is the best practice on neatly tying all of that stuff together?
On a somewhat related issue, I’ve had some of the plastic romex-keeper tabs break entirely off of the back of the box when I put the romex through…..the romex is of course nailed off near the box, but without anything holding it at the back of the box it is a little floppy. Should I plug around the romex with something in the box? It just sort of looks wrong…… –Ken
Replies
First off, I'm not an electrician.
It sounds to me like you should have a small sub panel with it's own isolated ground tied back to the main panel's ground. Or maybe I don't understand what you're doing. I don't like having different circuits in the same box. I don't think it's against code, I just don't like to do it. If this is one circuit controlling both lights and outlets, I really don't like that. And, I think that's against code. You don't want to be using a table saw, trip the breaker and find yourself in the dark holding one end of a sheet of plywood.
As for the tabs breaking off, I've just nailed off the romex near the box. I'd be curious as to what others do.
This is just a four-gang box; all switches and no outlets. Not a separate sub-panel or anything like that.
The table saw (and the other major tools) will be on its own dedicated 220 circuit.
For the lights, one circuit each for some ceiling mounted can "spot" lights over a work bench; main flourescent lighting (two banks off of one circuit) and a metal halide "low bay" task light (400 watt...and that sucker puts out an amazing amount of light!).
Overkill on having separate circuits for each lighting type, but I'm leaving room for futher expansion . . .
With two or even three gang boxes I've just tied all the grounds together and pig-tail to the switches. In the four gang box, especially with the three-way romex in there, too it just seems a bit messy..... --Ken
You might try breaking all the grounds up into two groups tied together with another ground pigtail.
When I've installed several outlets in a large multi-gang box I've looped all the grounds together with one long ground wire. But, that was easy because I could wire all the outlets together before I even put them in the box. Not so easy with separate switches.
what's wrong with a big wirenut ?
if you're tight for space you could probably use a jumper between smaller bundles......just remember which one is the ground from the panel........
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personally , I don't run Romex, only conduit, so somebody here may have the "best" solution, but a bigwirenut would be my choice...
that broken plastic thing??
I wouldn't worry about it..... jam some duct seal in there to keep bugs out
Easiest and cleanest I can come up with is twistem all up good and tite, leave or add a long enough strand for the pig tail, and crimp a copper crimp sleeve over the twisted wad.
If the wad is too big for a standard crimp sleeve, cut off a short hunk of soft copper tubing and cinch it down with channel locks.
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Sphere's comment: "Easiest and cleanest I can come up with is twistem all up good and tite, leave or add a long enough strand for the pig tail, and crimp a copper crimp sleeve over the twisted wad."This is what the inspectors here in Stafford County VA want to see in boxes larger than two gang. No green wirenuts for them in large boxes. You can leave 3 long wires for pigtails to three switches, or 4 longs for 4 switches. Or of course one really long one to jump between all switches. These crimp sleeves come in several sizes.As mentioned, read the back of the box inside for maximum number of wires allowed.Frank DuVal You can never make something foolproof because fools are so ingenious.
"If the wad is too big for a standard crimp sleeve, cut off a short hunk of soft copper tubing and cinch it down with channel locks." That is not an approved method of making a connection, there is no way I would ever do that......
The copper barrel crimps (Bucannans) are only approved if crimped with the Bucannan Crimp Tool, not lineman pliers or channel locks.
It is not a big deal to splice 8 grounds plus a long pigtail for the switches under a wire nut, just leave yourself enough wire to work with. If it is to hard to do split it into 2 wirenuts with a jumper as was previously suggested.
Have'nt any of you guys ever worked on knob tube wiring or the old style BX??? all the splices are soldered (splices dipped in a lead pot) and taped and they have worked without problems for decades, and this was long before they started soldering electronics.
I agree with sphere - ground crimps are the standard for this job - with all that 3 wire make certain you aren't overloading your box -- buy a deep one!
I used to twist all my grounds together but man its hard bending and shoving it all back into box as opposed to individual wires crimped or nutted together.
bought the biggest, deepest one I could, because I knew I'd have a lot of cable in it....
For the grounds, there are several other options.
One is to use a WAGO connector. WAGO is a proprietary brand but Ideal makes a similar version. Home De Pot sells them. Little plastic things with holes in them. Strip the wire [1/2"?] and plug them in. Almost like backstab but better internal connection. Google WAGO.com. Some of these devices may accept up to 8 wires each.
If you use conduit you only need one ground wire per conduit. Or you could even use the metal conduit itself as the ground. Legal but conduit, EMT, sometimes falls apart due to heat/cold expansion/contraction.
On a recent project, I had a 12" X 12" by 6" deep metal box. It had about 38 MC circuits coming in and about 5 3/4" EMT conduits going out. How to tie all those grounds together? I went to the electrical supply house and bought a ground bar for $8. It worked perfectly. With grounds, it is usually acceptable [per listing] to have more than one green wire per hole.
As for the Romex clamps being broken, I think the Code has you staple ["support"] within 12" of the box but if no clamps them you must staple within 8".
~Peter
The recent Seattle-Tacoma earthquake was all President Cheney's fault.
Thanks. I'll look for that connector.
The problem with a wirenut is if I have individual pigtails I'd have something like 12 wires in one wirenut.....I can get it down to about 9 if I run one long pigtail and daisy-chain to each switch.
--Ken
On the cable fixing...I think the current NEC code requires a staple within 6 inches of a plastic box, which I've done. I'll probably just stuff some putty back in there. Nothing else it ought to minimize air infiltration (not a huge worry since this is a shop rather than a residence. --Ken
Per G-B, you can get up to six #12's in their #89 or H-2 wire nuts. Or, you could twist the whole shebang together and solder it.
-- J.S.
waitaminit, John. I thought that soldering was absolutely verboten by code.DonDon Reinhard
The Glass Masterworks
"If it scratches, I etch it!"
I thought so also. The AHJ in Contra Costa County, Calif., indicated that soldering of grounds was verboten - the heat from a short might melt the solder and open up the ground circuit.
Casey: Never got anything from an inspector - my understanding was a fear of corrosion w/i the solder joint or a cold joint, resulting in a high resistance to ground and a resultant danger to people getting across the voltage.DonDon Reinhard
The Glass Masterworks
"If it scratches, I etch it!"
In the 1999 NEC, Section 250-8 says "Grounding conductors and bonding jumpers shall be connected by exothermic welding, listed pressure connectors, listed clamps, or other listed means. Connection devices or fittings that depend solely on solder shall not be used." (For what it's worth, the next sentence bans sheet metal screws to connect grounding conductors).
One of those fortunate situations where the code is unambiguous.
OK, so twist and solder should be OK.
Solder is vastly superior to any other way of splicing wire. That's why we use it in electronics.
-- J.S.
Johjn: yabut, You have to be licensed to solder electronics. At least for military items. Corrosion in a solder joint is too easy to get for the inexperienced/incompetent.DonDon Reinhard
The Glass Masterworks
"If it scratches, I etch it!"
> You have to be licensed to solder electronics. At least for military items.
I've never heard of that. NASA in the very early days did have soldering school, and issued certificates. But their concern was with not nicking too many strands, not using too much solder because of the weight, stuff like that.
> Corrosion in a solder joint is too easy to get for the inexperienced/incompetent.
Corrosion is only an issue with acid fluxes. In electronics, we use rosin core, nobody ever sees any corrosion here.
-- J.S.
John: Last I knew, before retiring, was that only qualified personnel were permitted to solder, & you needed a license, essentially like a pressure vessel welder, and you had to periodically be re-qualified. When talking w/ some folks at Honeywell way back in the late 80's that was still the case. I also spoke w/ a woman whose husband had a small business that required soldering military electronics. She was in the process of getting qualified as a solderer.Corrosion may not be a problem, but "Cold joints" are, and that is a real problem. I've done some soldering, building some electronics kits and had problems w/ some cold joints, even using rosin core. I started out back in 1959 in the Nike Air Defense business, and none of the battery personnel were permitted to solder - anything that required a broken joint & re-soldering required that the board go to the next level of maintenance, where they had licensed solderers. Granted, that was back in the days of tubes (You know what they are, I presume - Grin) and a ton of wires, and there were a heck of a lot more individual solder joints. I recall seeing Honeywell manufacturing PC boards in 1990 in Atlanta using a wave soldering machine that got people completely out of the loop. I vaguely recall that on some first generation or second generation PC boards that a repair requiring soldering meant the board was returned to the factory unless it were a combat emergency.DonDon Reinhard
The Glass Masterworks
"If it scratches, I etch it!"
> Corrosion may not be a problem, but "Cold joints" are, and that is a real problem.
True, but a problem we can solve. Cold joints can result from having not quite enough soldering iron for the job. You just have to get the right tools and use them at the right temperatures.
A cold joint can also happen if you don't have things mechanically sound, and want to depend on the solder to hold them. If they move during cooling, you can get a really nasty cold joint.
Cold joints are usually fairly easy to tell by their dull surface, and fairly easy to fix.
-- J.S.
Uh, I don't know about the best way, but the way required for grounding is exothermic welding or pressure connectors or clamps (or other listed means). Solder won't cut it because it melts at too low of a temp.
Phil,
Depending on the compound, solder for electrical applications melts between 360*f and 600*f. The Kindling Point for wood is around 660*f.
Any heat to melt the solder on a well formed soldered connection is going to be coming from a source external to the connection.
If you're melting the solder, you've got major problems with the rest of your system.
A good soldered connection can be mechanically stronger than the wires it's connecting.
A good soldered connection has less resistance across it than the same length of the larger of the wires it's connecting.
However;
A soldered connection cannot be inspected without removing its' insulation.
Soldering takes much more skill and training than twisting a wire nut.
A poor solder job can be more dangerous than a poor wirenut job.
SamT
Edited 2/28/2006 8:15 pm by SamT
Sam:
I don't disagree with you. But if the house burns, or someone dies, failure to follow the applicable code is usually considered negligence per se and could be grounds for a criminal charge of negligent hommicide. If you are doing it for pay, the homeowner's insurance company will also pursue you in subrogation.
There is no question that if a ground connection melts solder, there are major problems (the heat source would be current flow through the ground wires, not external). But what the code is addressing in that specific situation is just that; something has gone horribly wrong but the ground bonding must be preserved -- if something is that wrong, odds of someone being hurt by an open ground have gone up quite a bit.
I don't mean to debate the relative merits of one connection method over another. I'm sure soldering would usually work (I mean really sure; that's how the best knob and tube circuits were run and the ones that were soldered are the ones that won't burn even if disturbed). The rules for grounding are pretty clear. I don't make the rules, I just try to follow them.
As an anecdote, I have been a trouble shooter on more than one system where there were over a hundred amps, on one many hundreds of amps, flowing through a grounding system (insustrial sites, but the principles still apply). That is not supposed to happen, obviously, but it can when everything else is not done just right. Anyway, my $.02.
Best regards,
-Keith
I'm not an electrician but do it once in a while on simple jobs.The book I follow was written by an old master electrician (Knight) who designed the book to aid apprentices in there journeyman test.He says that soldering is fine and sometimes necessary to avoid over-filling a box. A soldered joint apparently is not counted. Which makes sense as there is no wire nut taking up room.I am in Canada, so maybe a Canadian electrician will chime in.On a point of logic, it seems to me that if you have enough amperage and voltage running through a circuit to melt solder, then a wire nut or whatever is not going to save the show!Alan
"As an anecdote, I have been a trouble shooter on more than one system where there were over a hundred amps, on one many hundreds of amps, flowing through a grounding system (insustrial sites, but the principles still apply). That is not supposed to happen, obviously, but it can when everything else is not done just right. Anyway, my $.02.Best regards,-Keith"You know, but for others this is a reason grounding and neutral conductors are ONLY tied together at one point. The reason this ground current happens is usually because the neutral conductor has been connected to the grounding conductor in two or more places. When this happens, the neutral current now has two paths, both the neutral conductor and the grounding conductor. A parallel circuit. The neutral current is divided by both conductors (current ratio by the ratio of their resistance). So if the circuit is pulling 100 amps of neutral current, and the grounding and neutral wires are the same size, the ground wire will be passing 50 amps! Not a safe situation.
Frank DuVal You can never make something foolproof because fools are so ingenious.
Ummmm, I thought the earlier post
<i>"Connection devices or fittings that depend solely on solder shall not be used."</i>
indicated that the code specifically excluded twist & solder. Or are you saying twist, then solder, then wirenut? (In other words a mechanical as well as solder connection. I would worry in this case that the wirenut would grab only the solder, and then if the solder melted, the mechanical connection would fail and you'd be in worse shape than if you'd never soldered...)I think the primary reason solder is used in electronics is because it's damm near impossible to fit more than a couple gray wirenuts on a circuit board!! <g>I've never had to deal with the large number of grounds that you're tying together, but it seems like the majority of responses have encouraged crimp splices. I'm curious why you still want to solder, especially given its questionable status in the code?
> <i>"Connection devices or fittings that depend solely on solder shall not be used."</i>indicated that the code specifically excluded twist & solder.
No, as I read it, it excludes solder without a twist, something that would fall apart without the solder. Twist plus solder is not "solely" dependent.
> I think the primary reason solder is used in electronics is because it's damm near impossible to fit more than a couple gray wirenuts on a circuit board!! <g>
No, it's because solder gets you as close to zero resistance for the life of the system as you can get. We use it on big stuff, not just boards. Look at power supplies, power amplifiers, HMI's, UPS's, etc. We even solder the lugs onto 4/0 cable.
> it seems like the majority of responses have encouraged crimp splices. I'm curious why you still want to solder, especially given its questionable status in the code?
Because solder is better than crimping. It covers the whole surface, not just point contact. It forms an alloy with the copper, turning the whole thing into essentially one piece of metal. It gives you the lowest possible resistance, and therefore the least heat.
Somebody else mentioned corrosion. Try to corrode a solder joint, and it'll work until you corrode thru the wires. Do that with a crimp, and it'll corrode between the wires and fail far earlier than a solder joint.
Bottom line, code should not forbid better methods and require worse ones.
-- J.S.
Back home our standard for grounds is twist em together and add a crimp ring. Neat, tight, easy, works good.
Around Boise I've seen a number of various things including an electrician that just twists all the grounds and leaves them as is with no mechanical connection. It's surprising that our tight-ars inspector didn't call him on that one.
Not an electrian, but stayed at a Best Western last night.
Don
Beer was created so carpenters wouldn't deliver the morning paper.
hey I tought the smart guys stayed at Holiday Inn.......;>)
They probably do. Hey, never said I was smart. :-)
Beer was created so carpenters wouldn't rule the world.
And since my friendly Boise inspector is *closely* inspecting my work since I'm not an electrician....I have to be spot on.
Actually, he's been pretty good to work with so far. --Ken
And since my friendly Boise inspector is *closely* inspecting my work since I'm not an electrician....I have to be spot on.
Once again our Boise electrical inspector has been driving us crazy. We have him stop by to explain exactly what he wants for a strange situation. It then takes us three additional inspections for him to finally quit adding additional crap.
The kicker was, once he wasn't available and another inspector was covering for him. There was about $500 of hardware that he didn't think was required but the other guy did.
We went from the detached garage to the house and into a new addition with a new pannel. Between the original grounds and the new grounds we have about a half dozen grounds and one guy said a 7th--a uffer ground was required in our situation, the other guy said no.
Electrical inspection on new service--power company lineman waiting for the inspection to clear to move connection--inspector said it won't happen today, then approves it 5 minutes later.
Oh the games we play. :-)
I wonder if we have the same one. Jack? --Ken
Handlebar mustache?
Edited 2/23/2006 11:29 pm ET by IdahoDon
Nope. Cleanshaven.
I've used bugs for this type of connecting.
http://www.foxelectricsupply.com/content/products/ProductDetail.asp?qsCatID=24629&qsProductNo=8H
Bugs? Around here thems is split bolts.Frank DuVal You can never make something foolproof because fools are so ingenious.
Cable clamps/split bolts same/same here too...bugs is a new one one me...just out of curiousity...are these switches single poles? if so, since when do we attach ground? leave the incoming ground extra long, after running it to the box screw twist it up with the rest and clamp 'em, then pigtail as needed off the long tail of the incoming....
The switches need to have a ground wire attached when screwed to a plastic box.Frank DuVal You can never make something foolproof because fools are so ingenious.
We call 'em bugs in Philly too.
Ring em out. It is 20 minutes out of your life and the grounds need to be identified to the circuit. It is a slippery slope to calling all common's the same too.
The commons in my old house were mixed as well. When you get that tingle on a dead circuit and then find 27 to 50 volts on the common you have to wonder.
It isn't that hard. Just take your time. Oh yea, pitch the plastic and go for steel or at least get replacement plastic boxes. They are only 97 cents each. The steel ones take more abuse in a shop
In other words, you'd say don't tie the grounds in a box together?
Yes tie em together but sort out the circuits. The wiring plan sounded pretty murky in the first paragraph of your original description.
We all know the white and the green / bare copper go to the same place in the main load center---eventually. My point is there are quirks that make them unequal potentially. Examples are a GFI circuit, secondary load center, or just plain shoddy wiring cobbled together from the source to the box you are working on.
It's sort of like washing your hands after going to the bathroom. yea, you probably won't die or even get sick but chances are some day something can happen that isn't good.
I just flash back to my old house and a circuit that should have been dead wasn't. All because someone tied together the common from a different circuit. Nothing to die from but not good practice either.Jack of all trades and master of none - you got a problem with that?
The wiring plan is clear enough (to me anyhow). Probably just a little sloppy on how I described it.
The biggest issue for me was looking at all the three way wires coming in a 4 gang box....and wanting to manage the conductors to get a "good and workmanlike" installation. --Ken
I appreciate the issue. I have one memorable 3 gang box with two 4 ways in it. Wire tags (brady brand) were a great help. Still it consumed hours of work.
The best help was the different type of wirenut I switched to. I have stepped away from the std wirenut twist on type. Instead I use the Wago, Buchannan or Ideal 'push nut' type of wire connector.
Std wirenuts get applied to a twisted tumid collection of like conductors. After the nut is applied this is like bending a curtain rod and tucking it back in the back of the box. (broken plastic box tabs sound familiar?) If you use the pushnuts you instead have 4 or more wires all straight and parallel connected at the end. Now when you try to tuck it in the box you have a very bendable structure. it tucks much easier and assembles much faster.
Electrical supply houses have one or all types in house. The only real issue is that they (pushnuts) don't like the fine strand wire like is found on light fixtures. There is some hard to decipher legend that describes the number of strands per ga on the pushnut box but suffice it to say that solid wire is best.Jack of all trades and master of none - you got a problem with that?