# Wire to large for breaker



## Nicecrispies (Mar 16, 2009)

I have to supply a 20 A receptacle 350 feet away, my questions is I have to run #4 awg for it and the breaker will only hold up to #8 .Is there any kind of lug that would fit in the breaker and connect to the wire or is there another way that you can think of ? Thanks


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## electricista (Jan 11, 2009)

Nicecrispies said:


> I have to supply a 20 A receptacle 350 feet away, my questions is I have to run #4 awg for it and the breaker will only hold up to #8 .Is there any kind of lug that would fit in the breaker and connect to the wire or is there another way that you can think of ? Thanks


Just splice a short piece of #8 to the #4


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## 480sparky (Sep 20, 2007)

Ditto. #12 would be fine as well.


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## steelersman (Mar 15, 2009)

so does the phrase: "something can only be as strong as it's weakest link" 

not apply to this situation?


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## micromind (Aug 11, 2007)

Indeed it does, in this case the weakest link is the trip unit inside of the 20 amp breaker. 

The #4 is sized larger to compensate for voltage drop. The 20 amp breaker still protects the #12. 

Most likely, there'll be a similar pigtail at the other end. Not many 20 amp devices will accept a #4.

Rob


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## patriot1 (Feb 16, 2009)

Agree with steelersman. Your short piece is the weakest link (not the show)... what type of load do you have that requires #4? Big load... a #8 will do the job if a small load


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## electricista (Jan 11, 2009)

patriot1 said:


> Agree with steelersman. Your short piece is the weakest link (not the show)... what type of load do you have that requires #4? Big load... a #8 will do the job if a small load


 The load is 20 amps or less. The #12 pigtail is fine.


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## electricista (Jan 11, 2009)

Nicecrispies said:


> I have to supply a 20 A receptacle 350 feet away, my questions is I have to run #4 awg for it and the breaker will only hold up to #8 .Is there any kind of lug that would fit in the breaker and connect to the wire or is there another way that you can think of ? Thanks


Let me open up a can of worms. What size EGC did you run?


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## user5941 (Mar 16, 2009)

6 or7 inches of #8 would not greatly affect the overall resistance in the circuit


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## 480sparky (Sep 20, 2007)

steelersman said:


> so does the phrase: "something can only be as strong as it's weakest link"
> 
> not apply to this situation?


How can a 20a breaker overload a short piece of #12?



patriot1 said:


> Agree with steelersman. Your short piece is the weakest link (not the show)... what type of load do you have that requires #4? Big load... a #8 will do the job if a small load


It's not the load... it's voltage drop.


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## patriot1 (Feb 16, 2009)

dont care about VD right now, what the load? then the VD. We dont know the situation either. Why not pull a #4 220 volt service and set a small sub?


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## steelersman (Mar 15, 2009)

480sparky said:


> How can a 20a breaker overload a short piece of #12?


I agree, it won't (unless the breaker fails) but I was just wondering about the whole voltage drop thing. Is it possible that one would be defeating the purpose of upsizing the conductor to overcome voltage drop, by using a #12 or #8 pigtail? I'm not saying that it will or won't, I'm just wondering what the opinions on this are.


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## william1978 (Sep 21, 2008)

electricista said:


> Let me open up a can of worms. What size EGC did you run?


 
I was thinking the exact same thing.


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## steelersman (Mar 15, 2009)

patriot1 said:


> dont care about VD right now, what the load? then the VD. We dont know the situation either. Why not pull a #4 220 volt service and set a small sub?


because he already has a service. Maybe you meant sub instead of service. It would become a feeder to a sub, not a service.


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## Nicecrispies (Mar 16, 2009)

Thanks for the replies, Inspector will not let me splice in the panel so was trying to avoid the extra teck connectors , pvc box and a little time . I guess I will have to bite the bullet though.Thanks again


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## electricista (Jan 11, 2009)

steelersman said:


> I agree, it won't (unless the breaker fails) but I was just wondering about the whole voltage drop thing. Is it possible that one would be defeating the purpose of upsizing the conductor to overcome voltage drop, by using a #12 or #8 pigtail? I'm not saying that it will or won't, I'm just wondering what the opinions on this are.


A short piece (6" or so) of #8 will make no difference. You can actually calculate the VD using the 2 different sizes if you don't believe it.


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## william1978 (Sep 21, 2008)

Nicecrispies said:


> Thanks for the replies, Inspector will not let me splice in the panel so was trying to avoid the extra teck connectors , pvc box and a little time . I guess I will have to bite the bullet though.Thanks again


 Wait what size ground are you pulling?


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## user5941 (Mar 16, 2009)

william1978 said:


> I was thinking the exact same thing.


 an increase in wire size for voltage drop requires a corasponding increase in the grounding conductor


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## patriot1 (Feb 16, 2009)

Thought the whole idea of VD is large wire to smaller wire, not smaller wire to larger. Breaker will hold unless the VD and the load is over the breaker rating. How about a 40 amp breaker to a fuse block and install a 20 amp fuse, the block will carry the #4.


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## electricista (Jan 11, 2009)

Nicecrispies said:


> Thanks for the replies, Inspector will not let me splice in the panel so was trying to avoid the extra teck connectors , pvc box and a little time . I guess I will have to bite the bullet though.Thanks again


Must be a Canadian rule about splicing in the panel because it is legit here in the US.


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## electricista (Jan 11, 2009)

william1978 said:


> Wait what size ground are you pulling?


The canadian rules may be different on the EGC art. 250.122(B)


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## patriot1 (Feb 16, 2009)

Case ground is considered per the breaker size, neutral must be the same as hot. Service ground per feeder size


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## Nicecrispies (Mar 16, 2009)

Its is for a receptacle on a dock, I am going to run 4/3 teck cable so the ground should be the correct size


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## patriot1 (Feb 16, 2009)

who is from canada?


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## 480sparky (Sep 20, 2007)

patriot1 said:


> Thought the whole idea of VD is large wire to smaller wire, not smaller wire to larger. Breaker will hold unless the VD and the load is over the breaker rating. How about a 40 amp breaker to a fuse block and install a 20 amp fuse, the block will carry the #4.


Voltage drop has nothing to do with large wire to small wire v. small wire to large wire. There's no NEC requirement that the entire ciruit be a larger conductor. It matters not in VD where the smaller wire is in the circuit. 

In parking lot lights, I typically run #12 from the breaker to the contactor. From the contactor, I run the larger (6, 8, 2, whatever) out to the lights. I run #10 up the poles. 

It's all on a 20a breaker, so it's all legal. The short sections of smaller conductor have little effect on voltage drop.


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## patriot1 (Feb 16, 2009)

never mind...haha


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## electricista (Jan 11, 2009)

patriot1 said:


> who is from canada?


Nicecrispies


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## Nicecrispies (Mar 16, 2009)

I wish we could splice in the panel it would save a lot of work at times


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## steelersman (Mar 15, 2009)

Nicecrispies said:


> I wish we could splice in the panel it would save a lot of work at times


you can't? What do you do when some of the wires are too short in a service upgrade or changeout?


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## electricista (Jan 11, 2009)

Nicecrispies said:


> Its is for a receptacle on a dock, I am going to run 4/3 teck cable so the ground should be the correct size


 In the NEC the egc would need to be the same size as your ungrounded conductors. In this case #4 since you are upsizing for VD from a #12 to a #4.


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## patriot1 (Feb 16, 2009)

a panel is not a j-box. sometimes joints have to be made as in a shunt trip.


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## steelersman (Mar 15, 2009)

patriot1 said:


> a panel is not a j-box. sometimes joints have to be made as in a shunt trip.


that's not what I heard over at MH's. Panel can be used as a J-box. Where does it say that it can't?


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## 76nemo (Aug 13, 2008)

steelersman said:


> I agree, it won't (unless the breaker fails) but I was just wondering about the whole voltage drop thing. Is it possible that one would be defeating the purpose of upsizing the conductor to overcome voltage drop, by using a #12 or #8 pigtail? I'm not saying that it will or won't, I'm just wondering what the opinions on this are.


 
Think of it in a manner that the #4 carries full voltage near to the device, somewhat as a sub was mentioned being put in near the recep area . A 20A breaker protects at it's rating regardless of wire size. The #4 carries full V to the area, and then spliced to the device. The problem of VD is therefore solved.


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## electricista (Jan 11, 2009)

patriot1 said:


> a panel is not a j-box. sometimes joints have to be made as in a shunt trip.



Read art. 312.8 of the NEC



> 312.8 Enclosures for Switches or Overcurrent Devices.
> Enclosures for switches or overcurrent devices shall not be used as junction boxes, auxiliary gutters, or raceways for conductors feeding through or tapping off to other switches or overcurrent devices, *unless adequate space for this purpose is provided*. The conductors shall not fill the wiring space at any cross section to more than 40 percent of the cross-sectional area of the space, and the conductors, splices, and taps shall not fill the wiring space at any cross section to more than 75 percent of the cross-sectional area of that space.


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## Nicecrispies (Mar 16, 2009)

We have to join the old wire with a new one in a junction box beside panel and put the new one in the panel


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## 76nemo (Aug 13, 2008)

steelersman said:


> that's not what I heard over at MH's. Panel can be used as a J-box. Where does it say that it can't?


 

You CAN splice in loadcenters by NEC, you may not be able to by your AHJ.


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## patriot1 (Feb 16, 2009)

steelersman said:


> that's not what I heard over at MH's. Panel can be used as a J-box. Where does it say that it can't?


 

pull your short wires out of the panel to above the ceiling in a j box. You can use your old panel as a j box but guts have to be removed and a new panel can be installed. it makes a messy job all those nuts:blink:


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## waco (Dec 10, 2007)

I splice in the panel all the time.

I have run temporaries on construction sites with #4. I just trim away a few strands until it will fit the breaker.

The voltage drop is continuous along the length of the conductor so the fewer strands at the breaker doesn't matter at all. Splicing a #8 or even a #12 would work as well. I think that setup was three #4 conductors with a #6 for an EGC.


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## 76nemo (Aug 13, 2008)

electricista said:


> Read art. 312.8 of the NEC


 

That's no different than discussing box fill for a 4" square.


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## patriot1 (Feb 16, 2009)

electricista said:


> Read art. 312.8 of the NEC


 
Very true, key words *unless adequate space for this purpose is provided*


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## steelersman (Mar 15, 2009)

electricista said:


> Read art. 312.8 of the NEC


Yes and after reading it, it says that I can. As long as ther is adequate space. Just use boxfill calculations and voila, there is sure to be enough space in the panel.


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## electricista (Jan 11, 2009)

waco said:


> I have run temporaries on construction sites with #4. I just trim away a few strands until it will fit the breaker.


Although this may raise a few hairs by an inspector it is certainly a good solution.


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## 76nemo (Aug 13, 2008)

patriot1 said:


> pull your short wires out of the panel to above the ceiling in a j box. You can use your old panel as a j box but guts have to be removed and a new panel can be installed. it makes a messy job all those nuts:blink:


 

Can you please quote and highlight that statement in the NEC????


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## electricista (Jan 11, 2009)

steelersman said:


> Yes and after reading it, it says that I can. As long as ther is adequate space. Just use boxfill calculations and voila, there is sure to be enough space in the panel.


Now go back and read my post and you will see that I was responding to Patriot, not you. I agree you can splice in the panel.


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## waco (Dec 10, 2007)

I think I see the issue. We don't run old wiring into a new panel, well, not if there are many wires, but we do "gut" the old panel and make our splices in there when we have to hook up to (usually) very old wiring -- like knob and tube.


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## william1978 (Sep 21, 2008)

Welcome to the forum Nicecrispies look what started on your 1st post.:thumbsup::laughing:


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## 480sparky (Sep 20, 2007)

electricista said:


> In the NEC the egc would need to be the same size as your ungrounded conductors. In this case #4 since you are upsizing for VD from a #12 to a #4.


Not always true. If you have #6s for a 50a circuit, you are allowed a #10 ground. T250.122. If you increase the wire size to 4 for VD, then you only need a #8 ground.


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## steelersman (Mar 15, 2009)

electricista said:


> Now go back and read my post and you will see that I was responding to Patriot, not you. I agree you can splice in the panel.


sorry man. quoted the wrong guy!


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## electricista (Jan 11, 2009)

480sparky said:


> Not always true. If you have #6s for a 50a circuit, you are allowed a #10 ground. T250.122. If you increase the wire size to 4 for VD, then you only need a #8 ground.



I agree but I was talking about the OP's case. I specifically mentioned upsizing from a #12 in my post

If your starting point is a wire size #14, #12 or #10 then the EGC gets upsized to the same size as the ungrounded conductors got upsized to. As 480Sparky stated this does not hold true for the other sizes.


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## Nicecrispies (Mar 16, 2009)

william1978 said:


> Welcome to the forum Nicecrispies look what started on your 1st post.:thumbsup::laughing:


Thanks , I've been reading for awhile . It's great to have a place to get such good information


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## heel600 (Oct 31, 2007)

480sparky said:


> Not always true. If you have #6s for a 50a circuit, you are allowed a #10 ground. T250.122. If you increase the wire size to 4 for VD, then you only need a #8 ground.


I don't see where it says if you upsize the conductors, you must upgrade the grounding.

The egc is based on the over current rating


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## 480sparky (Sep 20, 2007)

heel600 said:


> I don't see where it says if you upsize the conductors, you must upgrade the grounding.
> 
> The egc is based on the over current rating


Try 250.122(B).


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## sparky970 (Mar 19, 2008)

Nicecrispies said:


> I have to supply a 20 A receptacle 350 feet away, my questions is I have to run #4 awg for it and the breaker will only hold up to #8 .Is there any kind of lug that would fit in the breaker and connect to the wire or is there another way that you can think of ? Thanks


What kind of 20A receptacle will accept #4? It seems like you are going awfully large for only 350'.


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## brian john (Mar 11, 2007)

heel600 said:


> I don't see where it says if you upsize the conductors, you must upgrade the grounding.
> 
> The egc is based on the over current rating


And fault current knows about voltage drop.


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## brian john (Mar 11, 2007)

sparky970 said:


> What kind of 20A receptacle will accept #4? It seems like you are going awfully large for only 350'.


 
When installing long runs of over sized conductors to compensate for VD, it is very common to splice an appropriately sized conductor at either end of the run to permit termination.


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## sparky970 (Mar 19, 2008)

brian john said:


> When installing long runs of over sized conductors to compensate for VD, it is very common to splice an appropriately sized conductor at either end of the run to permit termination.


I understand that, but 350' is not very far. I haven't done the calculation, but what is the voltage drop on 350' on a #8?


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## JohnJ0906 (Jan 22, 2007)

sparky970 said:


> I understand that, but 350' is not very far. I haven't done the calculation, but what is the voltage drop on 350' on a #8?


Keep in mind that if the receptacle is 350' away (per OP) the VD calculation is based on the circuit length - 700'


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## brian john (Mar 11, 2007)

350' IS DAMN FAR.. 
At 16 amps 120 VAC

Size: --- Current:amps*Solution:* 1 conductor(s) per phase utilizing a 4 kcmil Copper conductor will limit the voltage drop to 2.68% or less when supplying 16 amps for 350 feet on a 120 volt system.



I have been there done this too many times as a 3rd party inspector verifying between what was asked for and what was delievered.

Over 65' is too far for a #12awg if specs limit you to 3% VD

Current:amps*Solution:* 1 conductor(s) per phase utilizing a 10 AWG Copper conductor will limit the voltage drop to 1.82% or less when supplying 16 amps for 65 feet on a 120 volt system.


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## brian john (Mar 11, 2007)

Number 8 at 350' 16 amps 7.1 %, 8.5 VAC drop at 120 VAC


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## electricista (Jan 11, 2009)

sparky970 said:


> I understand that, but 350' is not very far. I haven't done the calculation, but what is the voltage drop on 350' on a #8?


Remember it is 350' one way. Using a VD calculator with a 12 amp load and 350 feet you would need a #4 to stay within the 3% drop. Now remember this is not an NEC requirement but a FPN.


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## brian john (Mar 11, 2007)

See Below


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## brian john (Mar 11, 2007)




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## electricista (Jan 11, 2009)

Nice table Brian. I think it really surprises people when the see how far even 100 feet can be with a large load on the circuit.


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## heel600 (Oct 31, 2007)

brian john said:


> And fault current knows about voltage drop.


 
Hold on a minute, let me take my foot out of my mouth. <plop> 

OK now...

I looked closer at 250.122 and saw that if I upsize the conductor, I need to upsize the EGC. 

That being said, if you upsize the CCCs so you only have a 3% voltage drop, upsizing the EGC that much is just overkill.


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## 480sparky (Sep 20, 2007)

heel600 said:


> ........That being said, if you upsize the CCCs so you only have a 3% voltage drop, upsizing the EGC that much is just overkill.


Why is it overkill?


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## crazyboy (Nov 8, 2008)

480sparky said:


> Why is it overkill?


X2........


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## brian john (Mar 11, 2007)

heel600 said:


> , upsizing the EGC that much is just overkill.


It is about a low impedance path for operation of the OCP


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## patriot1 (Feb 16, 2009)

I think T and B makes an adapter for that, simply a crimp on, keeps the integrity on the #4.


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## heel600 (Oct 31, 2007)

480sparky said:


> Why is it overkill?


Don't have the NEC handy, so bear with me....

Why can I use a #8 as the EGC to a 100 amp sub panel that is fed with #4, but if I run a #4 400' or so on a 20 amp breaker, I need a #4 EGC.

Are you (or Brian John) saying that if I used a #8, or even a #10 that the fault would not trip the 20 amp OCPD?

I understand if the EGC were so small, and the run so long, that it would act as a resistor, and not cause the OCPD to trip.


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## frenchelectrican (Mar 15, 2007)

heel600 said:


> Don't have the NEC handy, so bear with me....
> 
> Why can I use a #8 as the EGC to a 100 amp sub panel that is fed with #4, but if I run a #4 400' or so on a 20 amp breaker, I need a #4 EGC.
> 
> ...


 
Voila! C'est le mot clef de la situation entière là. Maintenant vous savez pourquoi nous avons à en haut la taille le conducteur pour cela très la raison.

( Voila! that is the key word of the whole situation there. Now you know why we have to up size the conductor for this very reason. )

Merci,Marc


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## Jeff000 (Jun 18, 2008)

steelersman said:


> you can't? What do you do when some of the wires are too short in a service upgrade or changeout?


Splitter boxes are used a lot here. (without the lugs in side, so I guess gutter box). All the commercial jobs I have done and seen all the homeruns go through a splitter box and then go into the breaker box, this way any splices can be made in the splitter. 


Its too bad the OP couldn't just utilize a higher voltage device so a smaller conductor could be used.


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## 480sparky (Sep 20, 2007)

heel600 said:


> Don't have the NEC handy, so bear with me....
> 
> Why can I use a #8 as the EGC to a 100 amp sub panel that is fed with #4, but if I run a #4 400' or so on a 20 amp breaker, I need a #4 EGC.
> 
> ...


Why? That's what the NEC says, that's why. I never said it makes sense. I only said it was wierd.


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## Joefixit2 (Nov 16, 2007)

If he won't let you splice in the panel why don't you get some reducing pins? Or else put a j box at the panel and splice there.


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## brian john (Mar 11, 2007)

heel600 said:


> Are you (or Brian John) saying that if I used a #8, or even a #10 that the fault would not trip the 20 amp OCPD?
> 
> I understand if the EGC were so small, and the run so long, that it would act as a resistor, and not cause the OCPD to trip.


Exactly. Which is the theory behind requiring an increase in the EGC with the CCC's. There should probably be a caveat as the sizes of the CCC's go up, but it is what it is.


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## ce2two (Oct 4, 2008)

:laughing: there are 1500 foot runs of 3/0 thhn /thwn feeding say a amber alert sign , the concrete pull-box next to service ped... to splice in ..the 3/0 must fit in a 80 amp breaker ,so we would have splice per . state req. a #4 thhn/thwn to 3/0 thhn/thwn ....food for thought state jobs ,if pvc is run you must u s e bare ground with power wires  the #4 into the 80 amp bkr......these distances are very common:laughing:


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## electricista (Jan 11, 2009)

ce2two said:


> :laughing: there are 1500 foot runs of 3/0 thhn /thwn feeding say a amber alert sign , the concrete pull-box next to service ped... to splice in ..the 3/0 must fit in a 80 amp breaker ,so we would have splice per . state req. a #4 thhn/thwn to 3/0 thhn/thwn ....food for thought state jobs ,if pvc is run you must u s e bare ground with power wires  the #4 into the 80 amp bkr......these distances are very common:laughing:


What size egc is the state requiring and why must it be bare?


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## brian john (Mar 11, 2007)

electricista said:


> What size egc is the state requiring and why must it be bare?


There is a thought that a bare EGC works better in PVC, due to the non-conductive property of PVC, the bare EGC increases the chances of a ungrounded conductor with a nick shorting to the EGC.


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## electricista (Jan 11, 2009)

brian john said:


> There is a thought that a bare EGC works better in PVC, due to the non-conductive property of PVC, the bare EGC increases the chances of a ungrounded conductor with a nick shorting to the EGC.


Makes sense. I appreciate the explanation.


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## ce2two (Oct 4, 2008)

electricista said:


> Makes sense. I appreciate the explanation.


 Remember state of california jobs .A.K.A goverment work , they require that the ground wire be bare in PVC, CPVC ...I would rather use an insulated conductor my self ...My boss says no , so i do it his way ...his way or the highway ...any size ground wire i'm talking..........don't piss off the boss:no::boxing::2guns: if you don't want **** work for a long time:thumbsup:


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