If I'm running #10 conductors due to voltage drop from a 20A overcurrent device, would I be able to use a #12 bonding jumper at a j-box? All conductors are #10 including the EGC. Table 250.122 shows a #12 copper for a 20A Overcurrent Device. Just want to know if I can use a #12 bonding to the box or I would have to use the same size (#10) as the Equipment Grounding Conductors.
Bonding conductor size at J-Box
- Thread starter yfz450rr
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- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Art. 50.102(D) states that the bonding jumper be sized according to Table 250.122. It does not state that it must be upsized as the equipment grounding conductor is required in 250.122(B). I am not sure that is the intent but that is what is stated
I believe the proper section is 250.148.
IMO, the jumper is an EGC per the mentioned section... not an EBJ under 250.102(D)... so #10 would be required.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I don't see where 250.148 states we must size it to the upsized wire size. I think that is the intent but I don't see the wording to support it.
Read between the lines.
250.148 says the EGC must be connected to the box or through a permitted device (essentially, don't have that section open currently).
- Location
- Illinois
- Occupation
- retired electrician
You are pulling all #10s, you are not using #12, why would you even think about the size of the jumper?...just use some of the scrap #10. Codewise, as seen from the previous posts, the code is not clear.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
What is the bonding jumper being used for? If it's from the receptacle to a metal box you could use #12 if the device had #12 pigtails.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I agree but I am thinking the OP wants to use #12 because it is easier then the very rigid #10
Yes, using #12 is much easier than trying to bend a #10 solid or using a crimp terminals. But I guess another way to look at it, with the #10 you can change to a 30A overcurrent device, so #10 jumper would be required. Thanks for all the good answers.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
If it's a 20 amp circuit how could you change to a 30 amp OCPD?
He's using #10 to compensate for voltage drop. The circuit OCPD can be changed to 30A and still be compliant (in general)... but the voltage drop would not change for the same load.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I still don't see how you can take a circuit that needs a 20 amp OCPD and just throw in a 30 amp because the conductors are big enough. :?
I agree, the load or purpose of the circuit may prevent doing so from being compliant.. but in general it is not prohibited.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Well we don't know what the load is and in some case a 30 amp overcurrent protective device would be compliant.. 210.23(B)
- Location
- New Jersey
- Occupation
- Journeyman Electrician
It sounded to me like he was concerned that someone else would see #10 conductors and change the OCPD to 30 amps.
That's correct infinity. I will not change it to a 30A breaker, but who knows what the facility electrician would do in the future. The load is only a 20A general use receptacle, but if they bring a piece of equipment that requires a 30A circuit, then they might use it.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I have heard of inspectors who turned down jobs because of that. Easy fix-- put a tag on it.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
That would be fine if they changed all of the components of the circuit to 30 amps. We use #10 on 20 amp circuits all of the time so to me it's not an issue. Anyone competent electrician would not simply remove the 20 amp OCPD and replace it with a 30 amp OCPD.
They need a refresher course. :roll:
On that same note,,,,, I know a lot of competent electricians that would not chase #10's all the way to the end of the run to see if it was all #10 prior to slapping in a 30 amp breaker.
Also, most of the premade ground stingers with the screws you'd purchase at the supply house are mostly #12 not #10, so the question of the need for #12 or #10 bonding jumpers for a #10 ground wire that may happen to be in the box brings up an interesting point. Would a #12 Ground Stinger not do its job on a 30 Amp circuit?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
- Status