An inspector on a state highway project noticed that for a 240 volt street lighting system, the contractor has installed 1#6 and 1#8 conductors instead of the 2#8 called out in the plans. I know this is not standard practice for the conductors to be of different gauges but does the NEC specifically prohibit doing this? And what problems might this cause if any. The lighting system has LED luminaires.
Mismatched wire gauges in a 240 volt, one phase street lighting system
- Thread starter JBZE
- Start date
- Status
- Location
- Illinois
- Occupation
- retired electrician
No code issue or operational problems from on conductor being larger than what the circuit requires.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
The NEC doesn't care if the condcutors are different sizes. You would need to ask for a code reference to try and figure what he was thinking.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Mixing the sizes is no biggie.
One problem that can arise is the size of an EGC when upsizing circuit conductors, 250.122(B).
Is there an EGC?
One problem that can arise is the size of an EGC when upsizing circuit conductors, 250.122(B).
Is there an EGC?
120/240V or 240/480V single phase
120/240V or 240/480V single phase
Is this for a 120/240V single phase or 240/480V single phase lighting system and are you connecting them 240 L-L or 240L-N? We used 240/480V single phase for street lighting projects in our area which is why I'm asking. I can't site a code source at this time, but if it is 120-240V and you have it connected L-L, I would think there would be a code requirement for same sized conductors, but I cannot cite it at this time.
120/240V or 240/480V single phase
Is this for a 120/240V single phase or 240/480V single phase lighting system and are you connecting them 240 L-L or 240L-N? We used 240/480V single phase for street lighting projects in our area which is why I'm asking. I can't site a code source at this time, but if it is 120-240V and you have it connected L-L, I would think there would be a code requirement for same sized conductors, but I cannot cite it at this time.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
no, requirement to match sizes. Conductors just have to have correct ampacity.
MAC702
Senior Member
- Location
- Clark County, NV
Possibly done to lower voltage drop enough to meet a goal, and only one conductor needed to be bigger to do so.
Or he ran out of #8 and installed #6 instead of buying more.
Nothing against Code to have half of an upgrade unless it adversely affects conduit fill, and is otherwise done properly.
As mentioned, there is a Code that requires the EGC to be sized accordingly...
Or he ran out of #8 and installed #6 instead of buying more.
Nothing against Code to have half of an upgrade unless it adversely affects conduit fill, and is otherwise done properly.
As mentioned, there is a Code that requires the EGC to be sized accordingly...
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
See #4
4 answers to an electrical question
1. Code answer
2. AHJ answer
3. Toms answer
4. Truck answer
4 answers to an electrical question
1. Code answer
2. AHJ answer
3. Toms answer
4. Truck answer
kwired
Electron manager
- Location
- NE Nebraska
You could run one conductor copper and the other aluminum if you wanted as long as minimum ampacity requirements are met and overcurrent protection rules are met.
You can't mismatch conductors that are in parallel to one another for the purpose of making an overall higher current carrying capacity conductor.
You can't mismatch conductors that are in parallel to one another for the purpose of making an overall higher current carrying capacity conductor.
- Occupation
- Licensed Electrician
What's on the truck answer gets to be number one on the list at times.
But would you?
- Occupation
- Licensed Electrician
I wouldn't plan to but since there's no compromise in safety I would.
kwired
Electron manager
- Location
- NE Nebraska
What's on the truck rule kicks in sometimes. So does what is already there to work with rule.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
If the plans called for #6 and he installed #8 there would be an issue but certainly not if the installer used a larger conductor as you stated
Honestly this will be a non issue one month after installation because the wire will get stolen anyway. This happens all to frequently in my area of Texas at least, despite TxDOT placing concrete traffic barriers over pull boxes, burying pull boxes, etc. The lights will be out for months until they are replaced again with copper conductors. The municipalities started using aluminum conductors in the area and have seen a significant decrease in theft, but still have to repair the stripped conductors once the thief realizes they're aluminum they bail leaving a mess, but easier to repair than long runs of missing conductor.
wrobotronic
Senior Member
- Location
- Colorado
The only issue I would see is with the listing of the fixture itself. If the manufacturer doesnot explicitly state that upsizing is ok for their product there might be a problem with warranty issues. Granted being a govt project, I'm not certain warranties are an issue...
Plus if the picture calls for #8s, I would imagine that would be the issue the inspector is having.
Unless, you resubmitted to accommodate for the #6. My inspector looks at the picture and it better match or he fails the inspection. Rightly so I suppose, but certainly circumstances don't allow for such bureaucratic hoops when time is of the essence.
The inspector may also cite 110.12 for workmanlike installation violations? That might be a stretch, I realize, but it seems to be a go to for some inspectors who can't cite a section immediately or if there is no section to cite.
cheers.
Plus if the picture calls for #8s, I would imagine that would be the issue the inspector is having.
Unless, you resubmitted to accommodate for the #6. My inspector looks at the picture and it better match or he fails the inspection. Rightly so I suppose, but certainly circumstances don't allow for such bureaucratic hoops when time is of the essence.
The inspector may also cite 110.12 for workmanlike installation violations? That might be a stretch, I realize, but it seems to be a go to for some inspectors who can't cite a section immediately or if there is no section to cite.
cheers.
kwired
Electron manager
- Location
- NE Nebraska
Fixture listing not likely to have any (direct) conductor size requirements. May require minimum/maximum input voltage and you may need to figure out voltage drop based on your conditions and size accordingly.
Some AHJ's do inspect to plan specifications - IMO if they are your typical city/county/state inspector, they should only inspect to NEC or whatever code applies. Anything above and beyond code minimum should be up to the designer to approve/disapprove.
I agree on the 110.12 comment, and think it is one of those code sections that should almost never be cited, as it is too ambiguous. If it is cited it needs further support of what is non-workman like about the installation. I fail to see anything that can definitely be called non workman like about this, it is strictly opinion if you call it non workman like.
MAC702
Senior Member
- Location
- Clark County, NV
Agreed. Anything more than required by local laws, should be up to the builder to inspect independently. Permit fees pay for these AHJ inspections, and should be only as expensive as necessary for the government to do its job. I'm also not against an inspector pointing out something he happen to notice, either.
kwired
Electron manager
- Location
- NE Nebraska
Me neither. He may see something with your service that is NEC compliant, but nothing wrong with him stating that the POCO typically doesn't allow what you did. He shouldn't issue any correction notices for it though if it is NEC compliant.
If you used Siemens gear when designer specified Square D - that is between you and the designer and is none of city/state inspector's business as long as what they see complies with code.
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