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DrDrew
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1 edit

Spade lugs on receptacle wiring meet code?

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Are spade lugs allowed per NEC when wiring receptacles?

I don't like the way the wire is crimped nor do I like the ground wire screw down. Either way it just seems like adding crimped (especially poorly crimped like this) spade lugs are another point of possible failure.

This is the back of a L5-20 receptacle. The hot and neutral are stranded 12 gauge, the ground solid 12 gauge.

I found this at a site I take care of.


John Galt
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Perfectly acceptable.

The receptacle should have been a back-wired device suitable for stranded conductors, though. The receptacle shown is typically used with solid conductors.
--
The Truth is the foremost enemy of the State now.


Msradell
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reply to DrDrew
Actually since the hot and neutral are stranded wire this is probably the best way to terminate them. You can't just take stranded wire and wrap it around the screw like you do solid wire.


Raphion

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said by Msradell:

Actually since the hot and neutral are stranded wire this is probably the best way to terminate them. You can't just take stranded wire and wrap it around the screw like you do solid wire.
I would "tin" (saturate with molten solder) stranded wire to put it under a screw connector like that. Is that better or worse than using the crimp on lugs?


nunya
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reply to DrDrew
Perfectly fine. And, it looks like they actually used a proper crimping tool.


Msradell
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reply to Raphion
said by Raphion:

said by Msradell:

Actually since the hot and neutral are stranded wire this is probably the best way to terminate them. You can't just take stranded wire and wrap it around the screw like you do solid wire.
I would "tin" (saturate with molten solder) stranded wire to put it under a screw connector like that. Is that better or worse than using the crimp on lugs?
Probably about the same as crimp on lugs but tinning certainly takes a lot longer and isn't as safe (possible burns).


shdesigns
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said by Msradell:

said by Raphion:

said by Msradell:

Actually since the hot and neutral are stranded wire this is probably the best way to terminate them. You can't just take stranded wire and wrap it around the screw like you do solid wire.
I would "tin" (saturate with molten solder) stranded wire to put it under a screw connector like that. Is that better or worse than using the crimp on lugs?
Probably about the same as crimp on lugs but tinning certainly takes a lot longer and isn't as safe (possible burns).
Actually crimp connections are better, especially where there is vibration.

Soldering causes all the wires to flex at the end of the solder joint. They will fatigue and break at that point. That was pointed out when I had a device UL tested.
--
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John Galt
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1 edit
reply to DrDrew
"Tinning" is not allowed...although "tinned" wires are.
--
The Truth is the foremost enemy of the State now.


ArthurS
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Hamilton, ON
reply to Raphion
said by Raphion:

said by Msradell:

Actually since the hot and neutral are stranded wire this is probably the best way to terminate them. You can't just take stranded wire and wrap it around the screw like you do solid wire.
I would "tin" (saturate with molten solder) stranded wire to put it under a screw connector like that. Is that better or worse than using the crimp on lugs?
*Never* "tin" a stranded wire *prior* to crimping or putting under a screw connector. Over time the solder will compress, and make for a poor mechanical connection.


Raphion

join:2000-10-14
Samsara
Hmm, thanks guys, I think I might have a couple very high current DC connections to check on/redo...


whizkid3
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reply to DrDrew
Yeah, its perfectly fine. And, IMHO, the way to go with stranded wire. I used to wire receptacles all of the time with spade lugs and stranded wire. (And even ring lugs! I worked for a company where spade lugs were not allowed, because of reliability concerns. What a b|tch getting captive screws out of receptacles, and then putting them back in. Try it sometime.)

Its a poor photo, but on the other hand, I appears the insulation on the red wire is not fully into the yellow part of the lug exposing some of the bare wire. This is not proper if that's the case. They do look like they used a better crimper than the $2.99 model you get at any 99 cent store. I prefer a crimper that has a closed cycle (will not release once you've started the crimp), and crimps both the metallic ferule section and the insulation section of the lug.


Killa200
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said by whizkid3:

I worked for a company where spade lugs were not allowed, because of reliability concerns. What a b|tch getting captive screws out of receptacles, and then putting them back in. Try it sometime.)
The little stopping lip on the outlet's terminal screws are a pain, aren't they? lol

TheMG
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3 edits
reply to DrDrew
Properly crimped connections are actually one of the most reliable type of connections there is.

There's a reason why 90%+ of connections in modern aircraft involve some type of crimp (mind you, they do use precisely calibrated crimp tools not the el-cheapo things you find at most hardware and dollar stores).

Just give the wires a good tug, they should not budge at all if the crimp was done properly. Looking up into the end of the connector, you should see the strands protrude from the metal ferrule. Insulation should be inside the plastic part but should not be into the metal portion at all. Wire insulation too deep inside the connector or exposed bare wire past the plastic part is not a proper crimp. If the wire does not protrude from the end of the metal ferrule then it is not a proper crimp either.


DrDrew
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1 edit
said by TheMG:

Properly crimped connections are actually one of the most reliable type of connections there is.

There's a reason why 90%+ of connections in modern aircraft involve some type of crimp (mind you, they do use precisely calibrated crimp tools not the el-cheapo things you find at most hardware and dollar stores).

Just give the wires a good tug, they should not budge at all if the crimp was done properly. Looking up into the end of the connector, you should see the strands protrude from the metal ferrule. Insulation should be inside the plastic part but should not be into the metal portion at all. Wire insulation too deep inside the connector or exposed bare wire past the plastic part is not a proper crimp. If the wire does not protrude from the end of the metal ferrule then it is not a proper crimp either.
I took a Mil-Spec electronics assembly course years ago and proper spade lug assembly was a required testable skill..... the spade lugs on that outlet wouldn't have passed.

So I know what you and whiz are saying about the quality crimpers, visible wire, and double (ferule/insulation) crimp. Of couse NEC code doesn't require Mil Spec connectors.

Just making sure it was NEC compliant as I couldn't find any references to it after a quick search.
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rawgerz
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reply to whizkid3
said by whizkid3:

(And even ring lugs! I worked for a company where spade lugs were not allowed, because of reliability concerns. What a b|tch getting captive screws out of receptacles, and then putting them back in. Try it sometime.)
Wouldn't that require a bench vice and a high torque drill? Those screws must be 40-80 foot lbs to break loose cuz I've never gotten one out.
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cdru
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reply to whizkid3
said by whizkid3:

(And even ring lugs! I worked for a company where spade lugs were not allowed, because of reliability concerns. What a b|tch getting captive screws out of receptacles, and then putting them back in. Try it sometime.)
That's when a ring lug becomes a horseshoe lug with some side snips...


whizkid3
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2 edits
reply to rawgerz
said by rawgerz:

Wouldn't that require a bench vice and a high torque drill? Those screws must be 40-80 foot lbs to break loose cuz I've never gotten one out.
The right screwdriver, holding the receptacle in one's hand, and skill is all it takes. (The first twenty times or so, the screwdriver ends up making a hole in your hand, unfortunately. The pain - risk vs. reward - forces you to concentrate.)


SandShark
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reply to DrDrew
I hesitate to bring this up because we in this forum usually aren't nit-picky (yeah, right), but don't those connectors look a little over-sized for the wire? It looks like they used #10-12 connectors on #14 wire.


DrDrew
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said by SandShark:

I hesitate to bring this up because we in this forum usually aren't nit-picky (yeah, right), but don't those connectors look a little over-sized for the wire? It looks like they used #10-12 connectors on #14 wire.
Lugs are color coded for wire size:

* Red - 16 to 22 gauge wire
* Blue - 14 to 16 gauge wire
* Yellow - 10 to 12 gauge wire

So yellow lugs are for 10-12 gauge wire and that is 12 gauge wire, it's just that the lug is crimped around the wire and not crimped around the insulation too.
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fcisler
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reply to DrDrew
A "screw clamp" style back wiring will allow for direct insertion of stranded wire, correct? Is this also the case for the cup style washers? There's not a "special" outlet for stranded - is there?

Only other alternative would be to pigtail a piece of solid wire onto the stranded?


Killa200
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reply to whizkid3
said by whizkid3:

(The first twenty times or so, the screwdriver ends up making a hole in your hand, unfortunately. The pain - risk vs. reward - forces you to concentrate.)
This reminds me of why i have small little scars on the sides of my palms,


SandShark
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reply to DrDrew
I already pointed out that the connectors were for 10-12 gauge wire, but thanks for the info. Also, I know how to crimp a connector. I do it almost daily.

I know the OP stated the wire is 12 gauge, but I don't think we really know for sure, do we? You can tell from that photo? I know I can't. The white neutral wire looks 14 gauge to me. No disrespect to the OP, but if he's asking those types of questions about connections to a receptacle at a site he takes "care of", how do we really know? Also, I'd be curious to know what he means by "take care of". If he takes care of the electrical at the site, I'm wondering in what capacity he's doing this. His profile says he's a cable installer. If so, what's he doing working on receptacles?


DrDrew
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2 edits
I'm the OP, I have the receptacle in hand, but I'm not an electrician and don't work with stranded electrical wire. I know some basic NEC code, but not this particular aspect of it. I've never had to install receptacles with stranded wire. I've always dealt with solid wire receptacles.

The receptacle was removed from a mountain top headend during some old equipment cleanout. I know the wire is 12 gauge.

At this point I'm responsible for the RF wiring, RF equipment, and fiber equipment at the site. If I need electrical work done it's contracted out.

My experience in electronics flags those particular spade lugs as unacceptably assembled and since I'd don't recall seeing lugs on receptacles before, I questioned whether it was up to code to be assembled that way. I don't have a copy of the NEC close at hand and a quick search on the net didn't come up with any meaningful results, so I asked here knowing there are some electricians that frequent this forum.
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whizkid3
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1 edit
reply to fcisler
said by fcisler:

There's not a "special" outlet for stranded - is there?
Atcutally, yes. Its typically called a 'commercial back-wire receptacle' and has clamps to hold the wire that work similar to (but better than) the clamp shown holding down the ground wire in the photo above. They are suitable for solid or stranded wire, usually up to 10 gauge. I think we are talking about the same thing, though. Not really 'special' receptacles.

public

join:2002-01-19
Santa Clara, CA
reply to DrDrew
said by DrDrew:

I've never had to install receptacles with stranded wire. I've always dealt with solid wire receptacles.
Stranded wire is always preferred in industrial wiring. Solid wire tends to break after flexing a harness few times, especially with smaller gauge wire.


nunya
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I hate solid wire (until it's smaller than 18 ga). Solid wire is for amateurs.
If you take a peek at the UL Whitebook, you'll see most devices are rated for solid or stranded wire "unless otherwise marked". So take a gander a standard household receptacle and see what it says (I'm not going to spoil it).
However, there are certain instances and listings where strict termination guidelines must be met.

The long and short of it - use a commercial receptacle with stranded or use a termination intended for stranded. Don't be a cheap ass.
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patcat88

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reply to public
said by public:

said by DrDrew:

I've never had to install receptacles with stranded wire. I've always dealt with solid wire receptacles.
Stranded wire is always preferred in industrial wiring. Solid wire tends to break after flexing a harness few times, especially with smaller gauge wire.
Then how is extension cord banned from going in walls? I know 8 gauge and bigger are stranded but they aren't stranded the way extension cords are.


Raphion

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My guess would be that extension cords use an insulation not rated for higher temperatures.


whizkid3
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reply to patcat88
said by patcat88:

Then how is extension cord banned from going in walls? I know 8 gauge and bigger are stranded but they aren't stranded the way extension cords are.
Because rubber type flexible cables and lamp cord (two prevelant types of extension cords) are simply not manufactured with, nor required to be manufactured with, the properties of cabling suitable (insulation and jacket) for use hidden within building walls. It has nothing to do with their stranding or temperature rating to my knowledge.