Ground pigtail sizing

[Coyote556]

Gentlemen,

I had to run 10ga to many of the receptacles in the shop due to distance and voltage drop. I am using spec grade back wire outlets so the 10ga wire on the outlet connections is no problem, but on the ground screw for the outlets, the 10ga stranded is a nightmare. When I get to each box, can I use a 12ga ground pigtail to make things easier. I would like to pigtail off 12ga solid and attach to my 10ga stranded ground run. Is this legal? Thanks ahead of time

 

[wyliesdiesels]

Code legally no. By code if the ungrounded conductors are increased in size then the EGC needs to be increased proportionately as well.

But we need more info:

What type of outlets?

Breaker rating?

How long are these wires that u would nee to increase the wire gauge?

 

[Coyote556]

Wire is already all pulled and ready to go. Receptacles are 20a Cooper spec grade. The runs were around 140 feet. Each circuit is on a 20a breaker. Two Receptacles per box. There are two circuits feeding each box (one for left receptacle and one for right). The EMT between each box has five 10ga wires in it, two hots, two neutrals and a ground. This is for the two circuits that are feeding each box.

 

[Stuart in MN]

Specifically, it's covered in NEC 250.122. This discussion explains it further: http://ecmweb.com/forums/electrical-101/bonding-grounding/upsizing-equipment-grounding-conductor Look at the first paragraph in response #2

If the issue is just getting the stranded #10 wire wrapped around the grounding screw, you could use solid #10 for the pigtail.

 

[Dick in Wisconsin]

If the issue is just getting the stranded #10 wire wrapped around the grounding screw, you could use solid #10 for the pigtail.

Does the code allow a crimped ring terminal or spade to be crimped onto the stranded wire and connected to the outlet?

 

[600SL]

Wire is already all pulled and ready to go. Receptacles are 20a Cooper spec grade. The runs were around 140 feet. Each circuit is on a 20a breaker. Two Receptacles per box. There are two circuits feeding each box (one for left receptacle and one for right). The EMT between each box has five 10ga wires in it, two hots, two neutrals and a ground. This is for the two circuits that are feeding each box.

Sounds like you did exactly what I did. I ran 10ga about 140' 5 wire just like you, 7 in some places. Had to use 10 ga because of derating as well as VD concerns.

I ran grounds in 10 ga. to each box. Each ground was terminated to the box with ring type crimp on connectors and 1 or two 12 ga pigtails were connected to the box as well for grounding to each device.

In the picture shown there is 1 120V and 1 240V line coming into the box with a 10 ga ground and 2 12 ga pigtails. The pigtails do not have to be derated because they are not running through conduit.

 

[600SL]

Does the code allow a crimped ring terminal or spade to be crimped onto the stranded wire and connected to the outlet?

I hope so because I did it. I purchased pigtails premade that way. My inspector liked it.

 

[600SL]

Code legally no. By code if the ungrounded conductors are increased in size then the EGC needs to be increased proportionately as well.

But we need more info:

What type of outlets?

Breaker rating?

How long are these wires that u would nee to increase the wire gauge?

This sound right but shouldn't he be able to go two gages lower on the ground to begin with. 10 ga hots with 12 ga ground?

 

[wyliesdiesels]

Wire is already all pulled and ready to go. Receptacles are 20a Cooper spec grade. The runs were around 140 feet. Each circuit is on a 20a breaker. Two Receptacles per box. There are two circuits feeding each box (one for left receptacle and one for right). The EMT between each box has five 10ga wires in it, two hots, two neutrals and a ground. This is for the two circuits that are feeding each box.

First I have to ask why your runs are 140'? A subpanel would have most likely been better.

Second, since it sounds like these are all 120v circuits, u could have ran/shared one neutral between the 2 hots, saving you wire, aggravatioon and effort. Its called a MWBC or multiwire branch circuit. U would just have to make sure the 2 breakers feeding the hots are on opposite phases/have a handle tie.

Circuits below 30a have the same size EGC compared to the ungrounded conductors so a proportionate increase of the EGC will result with the same size as the ungrounded phase conductor...

So by code using #12 EGC pigtails wont pass code and could create issues...

Does the code allow a crimped ring terminal or spade to be crimped onto the stranded wire and connected to the outlet?

Yes it does as long as the connectors are U/L listed and rated for the voltage and current that they will be used with

Sounds like you did exactly what I did. I ran 10ga about 140' 5 wire just like you, 7 in some places. Had to use 10 ga because of derating as well as VD concerns.

I ran grounds in 10 ga. to each box. Each ground was terminated to the box with ring type crimp on connectors and 1 or two 12 ga pigtails were connected to the box as well for grounding to each device.

In the picture shown there is 1 120V and 1 240V line coming into the box with a 10 ga ground and 2 12 ga pigtails. The pigtails do not have to be derated because they are not running through conduit.

EGCs arent derated in the first place. Derating has to do with the ungrounded conductors....

This sound right but shouldn't he be able to go two gauges lower on the ground to begin with. 10 ga hots with 12 ga ground?

No. where did u come up with that? The EGC is based on the OCPD rating. For 15a 20a and 30a circuits, the EGC is the same size as the ungrounded conductors...

http://www.safecoelectric.com/images/resources_pdf/NEC2008 Table 250.122.pdf

 

[600SL]

First I have to ask why your runs are 140'? A subpanel would have most likely been better.[/URL]

In my case I did look into a subpanel and found that no mater what, the wiring would still need to be derated due to over 3 conductors in each conduit. So running direct killed two birds with one stone, the VD and the conduit fil. A sub panel would have only added cost.

Second, since it sounds like these are all 120v circuits, u could have ran/shared one neutral between the 2 hots, saving you wire, aggravatioon and effort. Its called a MWBC or multiwire branch circuit. U would just have to make sure the 2 breakers feeding the hots are on opposite phases/have a handle tie.[/URL]

I elected not to do that because it presents a risk of loosing both circuits if one were to go bad. Yes it would have been a lot simpler and the risk is small.

Circuits below 30a have the same size EGC compared to the ungrounded conductors so a proportionate increase of the EGC will result with the same size as the ungrounded phase conductor...

So by code using #12 EGC pigtails wont pass code and could create issues...
[/URL]

OK but he is running 20 amp circuits so the #12 ground pigtails connected to a #10 ground should be OK since I believe the requirement for his ground is only #12 to begin with. I did the same thing running a #10 ground the distance then pig tailing at the boxes with #12. My inspector like it but maybe he didn't notice. Your thoughts on this?

Yes it does as long as the connectors are U/L listed and rated for the voltage and current that they will be used with



EGCs arent derated in the first place. Derating has to do with the ungrounded conductors....
[/URL]

Exactly isn't that's why #12 pigtails in 20 amp circuits should be OK.

No. where did u come up with that? The EGC is based on the OCPD rating. For 15a 20a and 30a circuits, the EGC is the same size as the ungrounded conductors...
[/URL]

Correct I forgot about the lower current circuits. I read that when I was wiring my welder.

http://www.safecoelectric.com/images/resources_pdf/NEC2008 Table 250.122.pdf

 

[Norcal]

If you oversize/ increase the size of the ungrounded conductor, the grounding conductor must be increased, now I do not know if a short bonding jumper sized to the overcurrent protection of said circuit has to be increased also. 250.122(B)

 

[wyliesdiesels]

OK but he is running 20 amp circuits so the #12 ground pigtails connected to a #10 ground should be OK since I believe the requirement for his ground is only #12 to begin with. I did the same thing running a #10 ground the distance then pig tailing at the boxes with #12. My inspector like it but maybe he didn't notice. Your thoughts on this?

Exactly isn't that's why #12 pigtails in 20 amp circuits should be OK.

Correct I forgot about the lower current circuits. I read that when I was wiring my welder.

As Norcal and i have said, the EGC needs to be increased. Yes the evc only needs to be #12 just like the ungrounded/hot conductors. However,by code if the hot is increased in size then the egc needs to be as well...dont know about pigtails either. Code doesnt address that...

 

[C96]

Gentlemen,

I had to run 10ga to many of the receptacles in the shop due to distance and voltage drop. I am using spec grade back wire outlets so the 10ga wire on the outlet connections is no problem, but on the ground screw for the outlets, the 10ga stranded is a nightmare. When I get to each box, can I use a 12ga ground pigtail to make things easier. I would like to pigtail off 12ga solid and attach to my 10ga stranded ground run. Is this legal? Thanks ahead of time

In my opinion yes, you have already satisfied the NEC code requirement of 250.122 (B) by increasing the size of the EGC in the conduit run in proportion with the ungrounded conductor. Simply connecting a 6” #12 pigtail to the device will no way cause a voltage drop problem.

Code legally no. By code if the ungrounded conductors are increased in size then the EGC needs to be increased proportionately as well.

Agreed, but there is nothing in the code stopping you from decreasing the wire size back down once voltage drop has been accounted for.

Circuits below 30a have the same size EGC compared to the ungrounded conductors so a proportionate increase of the EGC will result with the same size as the ungrounded phase conductor...

Correction, 30a and below have the same size EGC

So by code using #12 EGC pigtails wont pass code and could create issues...

I disagree, again no where does it say you cant reduce wire size back down once the voltage drop issue has been compensated for.

If you oversize/ increase the size of the ungrounded conductor, the grounding conductor must be increased, now I do not know if a short bonding jumper sized to the overcurrent protection of said circuit has to be increased also. 250.122(B)

I think not, nothing indicating this needs to happen.

As Norcal and i have said, the EGC needs to be increased. Yes the evc only needs to be #12 just like the ungrounded/hot conductors. However,by code if the hot is increased in size then the egc needs to be as well...dont know about pigtails either. Code doesnt address that...

Exactly, it does not, therefore it should not be of concern. Using the 6” #12 pigtail is fine and would not pose any ill effects.

 

[ishiboo]

In my opinion yes, you have already satisfied the NEC code requirement of 250.122 (B) by increasing the size of the EGC in the conduit run in proportion with the ungrounded conductor. Simply connecting a 6” #12 pigtail to the device will no way cause a voltage drop problem.

It won't, no. But it's not code.

Agreed, but there is nothing in the code stopping you from decreasing the wire size back down once voltage drop has been accounted for.

Code requires a #10 EGC for the upsized #10 hot/neutrals. Nowhere is there an exception allowing you to throw a small portion of lower-gauge wire in there.

I disagree, again no where does it say you cant reduce wire size back down once the voltage drop issue has been compensated for.

#10 is required because he upsized it. There is nothing which says you can arbitrarily decrease the size due to what you feel like doing.

Exactly, it does not, therefore it should not be of concern. Using the 6” #12 pigtail is fine and would not pose any ill effects.

True. Except it doesn't meet code.

 

[teamextreme]

True a #12 pigtail doesn't technically meet code, but this is one of those situations where I would have no issue with doing it that way. Trying to get #10 on a ground screw is a pain and you risk not getting it tightened and staying tight with the huge #10 on there. I think it's technically a safer install using a #12 pigtail due to that. Plus, the upsized conductor is to provide larger current carrying capacity for ground faults back to the panel. If a ground fault occurred from a device being fed from the outlet, the little 6" piece of #12 will have such insignificant effect it's not worth considering, IMO. And a ground fault any other location would have zero effect one any other pigtails.

What about this hypothetical...You have the exact scenario of the OP, you run #10 to for the long run to reduce VD, but once at the destination, you have several outlets all within a very close proximity, so you go back to #12 for ease of install. The VD is knocked down because 90% of the distance is covered in #10. Would this not be allowed? If you are upsizing due to VD, is there a rule that says you have to remain with this upsized wire for the entire circuit? Remember, we're still legal with #12 on a 20amp circuit, we've just reduced from oversize to correct size.

 

[ishiboo]

True a #12 pigtail doesn't technically meet code, but this is one of those situations where I would have no issue with doing it that way. Trying to get #10 on a ground screw is a pain and you risk not getting it tightened and staying tight with the huge #10 on there. I think it's technically a safer install using a #12 pigtail due to that. Plus, the upsized conductor is to provide larger current carrying capacity for ground faults back to the panel. If a ground fault occurred from a device being fed from the outlet, the little 6" piece of #12 will have such insignificant effect it's not worth considering, IMO. And a ground fault any other location would have zero effect one any other pigtails.

I wouldn't be too concerned, but I think it would be simple to do legally with a crimped ring terminal, and worth it.

What about this hypothetical...You have the exact scenario of the OP, you run #10 to for the long run to reduce VD, but once at the destination, you have several outlets all within a very close proximity, so you go back to #12 for ease of install. The VD is knocked down because 90% of the distance is covered in #10. Would this not be allowed? If you are upsizing due to VD, is there a rule that says you have to remain with this upsized wire for the entire circuit? Remember, we're still legal with #12 on a 20amp circuit, we've just reduced from oversize to correct size.

Interesting question. I am guessing this is not permitted by the NEC, but I am not sure where.

I think the concern lies when you see a #10 in the panel with a 20A breaker, so you go okay I'll put it on a 30A. If there are different wire gauges in the same feed, it can be difficult to determine breaker sizing/etc. after the fact.

But obviously you could feed a sub-panel with a 20A breaker on #10 and have another 20A breaker in the sub feeding #12.

 

[Coyote556]

I appreciate all the comments and input. It sounds like it would not be code, but should not cause any safety concerns to do so. Where I live does not require any inspections, but I still wanted to do it correctly. I tried to run down some 10ga solid today at the box store and they do not stock it. I may have to go back to the electrical supply house to get it if I elect to go with 10ga solid instead of downsizing the pigtails.

 

[mm08822]

Buy a box of#10 ring or spade sta-kons and use the 10 stranded. All will then be to code. Forget using the 10 solid.

 

[600SL]

Interesting thread. It sound like in my case where I don't even need a ground due to conduit, the fact that I put one in and upsized it to #10 with #12 pigtails may not be to code.

One of those situations where code is code, and common sense is just not allowed. We have that all over the aviation industry.

It looks like the group consensus is that there is still uncertainty of weather or not this is to code but in any case most agree this not a safety issue.

In my recent inspection the inspector either did not notice that the ground pig tails were #12 or he felt it was to code. It may have been a different story if I pointed it out.

But code is code and we cannot hold inspectors accountable for our little deviations however brilliant they may be.

I'm willing to bet that if you asked 10 inspectors you would probably get about 5 going one way and 5 going another.

I for one am not going to re pig tail all my receptacle's.

 

[CoopVA]

It's fine. I wouldn't worry about it.


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[AlwaysFixingSomething]

All you have to do is splice all the conductors from #10 down #12 and it's legal by the NEC. You don't need the whole length of the circuit to be #10 to solve voltage drop issues. The last 6 inches of the circuit in #12 won't create any voltage drop issues either.

 

[wyliesdiesels]

All you have to do is splice all the conductors from #10 down #12 and it's legal by the NEC. You don't need the whole length of the circuit to be #10 to solve voltage drop issues. The last 6 inches of the circuit in #12 won't create any voltage drop issues either.

Care to share the particular code section that allows interchanged wire gauges?

 

[600SL]

One thing I did read that came with my garage door opener was that the opener will accept #12 max and if your conductors are larger they will need to be reduced to #12. That was from Liftmaster.

 

[Dagny]

are these conductors in emt by some chance?

 

[AlwaysFixingSomething]

Care to share the particular code section that allows interchanged wire gauges?

There is nothing in the NEC that prohibits what I said, it's done all the time. What if the guy needed a #8 circuit for voltage drop how would he terminate that onto a 20 amp receptacle?

You can mix conductor sizes as long as the OCP is sized to the smallest conductor in the circuit.

 

[Coyote556]

Yes, it is all in EMT. I knew a ground conductor was not required with EMT, but I pulled one anyway, for fear of a loose connection or something on the EMT.

 

[AlwaysFixingSomething]

Yes, it is all in EMT. I knew a ground conductor was not required with EMT, but I pulled one anyway, for fear of a loose connection or something on the EMT.

So what did you end up doing with the receptacles?

 

[Coyote556]

I have not done anything yet. I called an electrician known by a family member and he recommended dropping the ground pigtails to 12ga or crimping forked crimp on connectors to the ground screw. He said either is acceptable in his area. I guess I am still trying to decide what to do. Also, I am doing box fill calculations to make sure I am not going to be over on box fill.

 

[AlwaysFixingSomething]

I have not done anything yet. I called an electrician known by a family member and he recommended dropping the ground pigtails to 12ga or crimping forked crimp on connectors to the ground screw. He said either is acceptable in his area. I guess I am still trying to decide what to do. Also, I am doing box fill calculations to make sure I am not going to be over on box fill.

I had to refresh my memory and yes that is legal. The EGC is sized based on the size of the OCP (breaker) in table 250.122 of the NEC. In your case you have a 20 amp breaker correct? So 250.122 says minimum size #12 EGC so your good to go.

 

[Coyote556]

Yes I do have 20a breakers on all the circuits.

 

[C96]

In my opinion yes, you have already satisfied the NEC code requirement of 250.122 (B) by increasing the size of the EGC in the conduit run in proportion with the ungrounded conductor. Simply connecting a 6” #12 pigtail to the device will no way cause a voltage drop problem.

It won't, no. But it's not code.

Show us in the NEC where its not code…Good Luck with that!

Agreed, but there is nothing in the code stopping you from decreasing the wire size back down once voltage drop has been accounted for.

Code requires a #10 EGC for the upsized #10 hot/neutrals. Nowhere is there an exception allowing you to throw a small portion of lower-gauge wire in there.

There doesn’t need to be an exception because it’s perfectly legal to reduce the wire size back down.

It’s perfectly legal to start with #12 at the breaker, then increace wire size to #10, #8, #6, or what ever size is needed to accommodate for voltage drop providing the EGC is sized in proportion. Its also legal to reduce the wire size back down at the end of the run to the original #12 wire size once the voltage drop requirements have been met.

#10 is required because he upsized it. There is nothing which says you can arbitrarily decrease the size due to what you feel like doing

Lol, you keep saying this. Again, you can up size the wire and you can downsize it back providing the EGC has been sized in proportion with the upsized ungrounded conductor and the voltage drop limitations have been met.

Exactly, it does not, therefore it should not be of concern. Using the 6” #12 pigtail is fine and would not pose any ill effects.

True. Except it doesn't meet code.

Ok, again you keep saying this without any NEC code reference to back this up.
Please, by all means find the section that prohibits this and while you’re at it, find the section that prohibits changing wire size back and forth in a run that has been adjusted for voltage drop.

I think the concern lies when you see a #10 in the panel with a 20A breaker, so you go okay I'll put it on a 30A. If there are different wire gauges in the same feed, it can be difficult to determine breaker sizing/etc. after the fact.

Where conductors of higher ampacity are used for any reason, the ampere rating or setting of the specified overcurrent device (in this case a circuit breaker) shall determine the circuit rating. Therefore, you cannot randomly change the size circuit breaker just because the wires showing have a higher amp rating than the breaker protecting it.

 

[CoopVA]

You can pigtail it with #12 or use a #10 terminal connector.


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[wyliesdiesels]

Show us in the NEC where its not code…Good Luck with that!





There doesn’t need to be an exception because it’s perfectly legal to reduce the wire size back down.

It’s perfectly legal to start with #12 at the breaker, then increace wire size to #10, #8, #6, or what ever size is needed to accommodate for voltage drop providing the EGC is sized in proportion. Its also legal to reduce the wire size back down at the end of the run to the original #12 wire size once the voltage drop requirements have been met.



Lol, you keep saying this. Again, you can up size the wire and you can downsize it back providing the EGC has been sized in proportion with the upsized ungrounded conductor and the voltage drop limitations have been met.





Ok, again you keep saying this without any NEC code reference to back this up.
Please, by all means find the section that prohibits this and while you’re at it, find the section that prohibits changing wire size back and forth in a run that has been adjusted for voltage drop.



Where conductors of higher ampacity are used for any reason, the ampere rating or setting of the specified overcurrent device (in this case a circuit breaker) shall determine the circuit rating. Therefore, you cannot randomly change the size circuit breaker just because the wires showing have a higher amp rating than the breaker protecting it.

I am also interested in the code section that says that!!

 

[ddawg16]

I too am curious where it says you can't use #10 on a 20a ckt....and then pigtail in #12's at the end.

Otherwise, how would one handle derating?

 

[600SL]

Not grounding pig tails but here is an example of how conductor size can be reduced by taking advantage of 90°C rated wire when transitioning from 75° or 60° rated panels.

I would think the same logic would apply.