grounded - Page 1
Forum section: electronics / general

author: grifftech
author_rank: Frequent Contributor
timestamp: October 29, 2015, 04:09:43 am
content: what is the thinnest wire I can use for grounding a 15 Amp outlet

author: Monkeh
author_rank: Super Contributor
timestamp: October 29, 2015, 04:12:32 am
content: I suggest you consult your local code or an electrician. Preferably the latter.

author: SeanB
author_rank: Super Contributor
timestamp: October 29, 2015, 04:27:59 am
content: The same diameter as the supply wire in most cases. It has to be capable of handling the fault current to trip the protective device in case of a fault.

author: Cubdriver
author_rank: Unknown
timestamp: October 29, 2015, 05:43:37 am
content: In the US, 14AWG is the thinnest you can use for supply and ground in a 15A branch circuit, though in practice the ground should be at least as large as the supply wiring so if 12AWG feeds the receptacle, a 12AWG ground conductor would be a wise choice as well.-Pat

author: German_EE
author_rank: Super Contributor
timestamp: October 29, 2015, 10:33:52 am
content: Whatever your local electrical code requires.

author: calexanian
author_rank: Super Contributor
timestamp: October 29, 2015, 07:41:29 pm
content: Quote from: Cubdriver on October 29, 2015, 05:43:37 amCorrect. NEC specifies 14AWG copper conductor, however in practice nobody uses smaller than 12AWG because that is the standard Romex cable used in residential wiring. Typically that has a white sheath. It is common though for most houses to actually be run entirely in 10AWG which is typically yellow sheathed. What will happen typically with 14AWG is the series resistance of the cable at a specific length will create too much voltage drop.

author: Cubdriver
author_rank: Unknown
timestamp: October 29, 2015, 09:43:15 pm
content: Quote from: calexanian on October 29, 2015, 07:41:29 pmActually, I think #14 Romex has a white sheath, #12 yellow and I know #10 is orange.-Pat

author: calexanian
author_rank: Super Contributor
timestamp: October 29, 2015, 10:52:08 pm
content: Quote from: Cubdriver on October 29, 2015, 09:43:15 pmI am sorry, you are correct. Too many work projects toasting my brain.

author: Cubdriver
author_rank: Unknown
timestamp: October 30, 2015, 03:40:51 am
content: Quote from: calexanian on October 29, 2015, 10:52:08 pmNo worries; I know that feeling all too well. I can't imagine wiring the whole house with #10 - I just did mine with #12 for all but the lighting circuits, which were done with #14, and the #12 gets brutal to splice after a while. It's amazing how little movement it takes to work harden the ends of the wires and make them a bear to twist. I got really tired of making pigtail splices in receptacle boxes!-Pat

author: Monkeh
author_rank: Super Contributor
timestamp: October 30, 2015, 04:51:25 am
content: Quote from: Cubdriver on October 30, 2015, 03:40:51 amTop tip: Don't use stupid connectors which require you to work harden the copper.

author: crispy_tofu
author_rank: Super Contributor
timestamp: October 30, 2015, 05:05:24 am
content: This isn't really contributing to the discussion, but I'd just like to warn the OP that 15 amps can cause pain and injuries.

author: Monkeh
author_rank: Super Contributor
timestamp: October 30, 2015, 05:06:10 am
content: Quote from: crispy_tofu on October 30, 2015, 05:05:24 amSo can 50mA. He shouldn't play with it at all!

author: bills
author_rank: Frequent Contributor
timestamp: October 30, 2015, 05:21:11 am
content: I think the nec allows the ground to be 1 awg smaller for the ground IE: 14 ga for a 12 ga feed.I could be wrong and would not surprise me, my info was from over 10 years ago.

author: Monkeh
author_rank: Super Contributor
timestamp: October 30, 2015, 05:22:38 am
content: Quote from: bills on October 30, 2015, 05:21:11 amThat.. would be two gauges smaller. And very much the wrong way to arive at an appropriate conductor size..

author: bills
author_rank: Frequent Contributor
timestamp: October 30, 2015, 05:27:28 am
content: ?? Please explain, are you saying a 16 ga. ground for a 12 ga. feed ?bill

author: Monkeh
author_rank: Super Contributor
timestamp: October 30, 2015, 05:28:29 am
content: Quote from: bills on October 30, 2015, 05:27:28 am...You know there are odd numbers too, right?

author: bills
author_rank: Frequent Contributor
timestamp: October 30, 2015, 05:44:17 am
content: Yes the standard awg we use are 16,14, 12 and 10 for household wire May be some 8awg.our system uses 2 lines of 120-125 v and a common (neutral) the neutral and ground are connected togetherfor 220-250 v the two lines are used in series with the ground/ neutral connected together household wiring split the each of the 120v lines to half of the load or there about.What am I missing?Now to be a smart ass what does AWG mean ?

author: Monkeh
author_rank: Super Contributor
timestamp: October 30, 2015, 05:53:22 am
content: Quote from: bills on October 30, 2015, 05:44:17 amThat between 12 and 14, you have 13, making 14AWG two gauges smaller than 12..QuoteAnnoying Wire Gauge. Wait, no.. Awkward? Awful? Abysmal? Hang on, I think I've got it! American.

author: bills
author_rank: Frequent Contributor
timestamp: October 30, 2015, 05:55:58 am
content: Yes your rightIt is clear we sort of agree thanks for having a sense of humor.

author: Monkeh
author_rank: Super Contributor
timestamp: October 30, 2015, 05:59:00 am
content: I only wish my vocabulary at 6am could come up with more words beginning with A.Oh, yes, asinine, that's a good, multipurpose word. Bit tinny though.

author: bills
author_rank: Frequent Contributor
timestamp: October 30, 2015, 06:08:31 am
content: Just to think 2 peoples separated by a language.

author: Cubdriver
author_rank: Unknown
timestamp: October 30, 2015, 06:08:51 am
content: Quote from: bills on October 30, 2015, 05:21:11 amI haven't looked at the code books in a while, but I believe that in 240V circuits (120-0-120) in the US, the NEC allows theneutralto be one or two sizes smaller (can't recall exactly) based on the reasoning that as long as the load isn't 100% on one of the 120V lines, the neutral current will be less than that in the lines because their opposite phase will cause the neutral currents to cancel one another, resulting in the neutral current being equal only to the difference in the current in the two lines. Perhaps this is what you're thinking of? As I recall, I was able to use 2/0 line and ground conductors, and a 1/0 neutral in the feed lines from my meter box to the breaker panel when installing my 200A service a few years ago. I could look it up if anyone's interested. And this of course is US electrical code I'm referring to.-Pat

author: bills
author_rank: Frequent Contributor
timestamp: October 30, 2015, 06:27:27 am
content: I think we are in agreement that the grounds can be smaller the dis agreement is is in the awg wire sizes IE: 14/13 awgour British friend thinks that we use all the awg sizes , but we skip the odd sizes. maybe we should use the metric sizesno I like the awg sizes. but we digress .

author: Monkeh
author_rank: Super Contributor
timestamp: October 30, 2015, 06:32:45 am
content: Quote from: bills on October 30, 2015, 06:27:27 amWell, they ARE all used. Just because they're not common in electrical wiring doesn't mean they don't exist! Sorry, I just can't call 14AWG one gauge down from 12AWG. One size down in common cabling, but not one guage!As far as grounds being smaller.. sure. Hell, in all our standard cables (Romex equivalent), theyareone size smaller in the smaller cables. 2.5mm² has a 1.5mm² CPC, 1.5mm² has 1mm².. 1mm² has 1mm² CPC though, as it's the smallest conductor allowed in fixed wiring. 4mm² actually has a 1.5mm² CPC, which is a problem. On longer circuits, the impedance is often too high to allow operation of a protective device in the required time (not an issue of the cable failing, but of preventing exposed metalwork being live for too long).Which is why I say just jumping down a size is the wrong way to determine appropriate conductor size for ground.

author: bills
author_rank: Frequent Contributor
timestamp: October 30, 2015, 06:45:17 am
content: The question was can a smaller ground be used, Yes it can. would I do it NO! all the household and industrial wiring I have done I have used the same gauge wire for the ground as the line.It makes no sense to use a smaller gauge although you can according to the nec?It is just fun to argue with you all, but as electricians we have a duty not to stupid shit. we must make sure what we do is idiot proof .I worked for UPS for last 25 years and my wiring never was a danger to any one.

author: Monkeh
author_rank: Super Contributor
timestamp: October 30, 2015, 06:49:02 am
content: Quote from: bills on October 30, 2015, 06:45:17 amWhich is why we have calculations and measurements to assure us of the reality of the situation.There is NO need for the CPC to be the same size as a current carrying conductor so long as it can carry full circuit current indefinitely during a limited fault and can clear a greater magnitude of fault (ie. a short circuit) in the required time... now, if your code doesn't have the equations for this and you don't have the test equipment to perform them anyway...

author: Cubdriver
author_rank: Unknown
timestamp: October 30, 2015, 02:26:21 pm
content: I think we're splitting hairs here with regard to wire sizes, with one being literal and one dealing with common availability. When talking about mains wiring in the US, I'd say it's perfectly acceptable to say when going up or downonewire size for branch circuit wiring to mean skipping the odd gauges, as they're not used in the application at hand. In fact, other than when you get to sizes larger than about #4 AWG, I can't recall ever encountering one of the 'odd' (7, 9, 15, 19, etc) gauge sizes as an insulated hook up or machine type wire - the only place I've ever seen the odd gauges is in magnet wire used for transformer or motor windings, for instance, where the size granularity is needed due to the requirement to optimize things for both current capacity and space constraints.For practical purposes, if you go to the electrical supply store in the US and tell them you need the next size larger (or smaller) than #12 for AC mains wiring, they're not going to hand you a spool of #11 (or #13) magnet wire - they're going to give you #10 or #14 because that's what's made.So both are correct, one from a literal standpoint, and one from a practical standpoint. Only the viewpoints differ.-Pat

author: ajb
author_rank: Super Contributor
timestamp: October 30, 2015, 06:41:27 pm
content: Quote from: Cubdriver on October 30, 2015, 06:08:51 amFrom recollection, there are certain factors that determine whether or not the neutral is considered a "current carrying conductor" which in turn affects its sizing. When the neutral is only expected to carry the balance of the phase currents in a multi-phase branch circuit or feeder serving non-reactive loads, the neutral current will never be more than a single phase's current and depending on the demand factors applied a lower current may be used for sizing the neutral. Some situations may also require that the neutral belargerthan the phase conductors when serving loads with very poor power factor, such as large banks of phase angle dimmers.

author: ConKbot
author_rank: Super Contributor
timestamp: October 30, 2015, 09:03:41 pm
content: Quote from: calexanian on October 29, 2015, 07:41:29 pmWhere at have you seen this, or how new was the construction? Was it in a particularly large house or a commercial/industrial situation? Ive never seen 10 AWG copper to 15/20 amp outlets in a residential situation (I have seen 10 AWG aluminum to a 20A outlet, but thats a whole different mess). 14 awg for 15A circuits, and 12 awg for 20A circuits. The recommended 3% drop (per NEC) means 14 awg/15A is good for ~50ft, same with 12 AWG/20A With 10 AWG having 2.5x copper as 14 AWG, I cant imagine electricians throwing it in willy-nilly. But I dont think Ive done in any work in houses newer than the mid 90's.Either way, as stated, a protective earth / grounding conductor doesnt need to carry the full load, but usually 14 AWG grounds get used with 14 AWG wire (in 14-2 romex, etc) 12 AWG ground with 12AWG wire, its not untill you get to larger stuff that Ive seen reduced size neutral. Cerrowire NM-B 14-2, 12-2, and 10-2 all have matching ground wire gauges, its not until you get to the 8 or 6 AWG wire where the ground is smaller than the load-carrying conductors. (10AWG gnd for 8-2, 8-3, and 6-2, 8 AWG gnd for 4-3 and 2-3)Local codes may vary, but NEC has this tablehttp://www.homepower.com/sites/default/files/articles/ajax/docs/1_HP153_pg98_CodeCorner-1.jpgSo per NEC at least (again, local codes... ) 14 AWG should be fine for grounding a 15A breaker'd circuit.

author: Zero999
author_rank: Super Contributor
timestamp: October 31, 2015, 09:25:19 am
content: Quote from: Monkeh on October 30, 2015, 06:32:45 amYes, the maximum voltage on exposed metalwork, under fault conditions is 50V and the breaker should trip within a certain length of time which I don't remember and will look up if anyone wants to know.

author: SL4P
author_rank: Super Contributor
timestamp: October 31, 2015, 08:41:46 pm
content: OP, ask your insurance company.They're the one that has to accept what you do if there's a claim.

author: Tinkerer
author_rank: Frequent Contributor
timestamp: October 31, 2015, 11:20:45 pm
content: I am currently doing work on my house. There isnt any reason not to use the same sized wire for grounding as you used for hot. 12 wire is the accepted currently for 20A circuits and 14 for 15A which is primarily for lights and such.You are not supposed to mix wire gauges, or at least thats what my contractor tells me is according to code. He knows what hes doing as first inspection has passed. I am working on my own place in the house, easy to have more than just me doing stuff.

author: karoru
author_rank: Regular Contributor
timestamp: October 31, 2015, 11:38:52 pm
content: I don't want to sound cocky or something like that, but if author of the thread has to ask then he shouldn't be doing this kind of stuff (unless it's just a school design assignment on paper).If you want to do your own mains stuff, then local requirements and law is the bible.

author: NevDickens
author_rank: Newbie
timestamp: November 01, 2015, 04:01:57 am
content: Quote from: crispy_tofu on October 30, 2015, 05:05:24 amyep, but it only takes less than 1 amp to KILL you. So it might be wise to get a trained professional to help you out.

author: bills
author_rank: Frequent Contributor
timestamp: November 01, 2015, 04:17:29 am
content: Really we are worrying electrocuting someone because the ground wire is 1 size smaller please go and stick your finger in the outlet or up some where else.sorry should not post after a few glasses of wine.

author: NevDickens
author_rank: Newbie
timestamp: November 01, 2015, 04:36:21 am
content: Quote from: bills on November 01, 2015, 04:17:29 amI think maybe you need MORE wine and a good sleep.

author: bills
author_rank: Frequent Contributor
timestamp: November 01, 2015, 04:39:23 am
content: No two glasses are enough, but you are right time to shut down the computer. Please watch where you stick your finger.

author: NevDickens
author_rank: Newbie
timestamp: November 01, 2015, 04:44:41 am
content: :Quote from: bills on November 01, 2015, 04:39:23 am