Nathan (SD)
Member
In what instances do you use 2-2-2 instead of the most common 2-2-4 ?
- Thread starter Nathan (SD)
- Start date
rustyfarmall
Well-known Member
I buried about 100 feet of 2-2-4 to my shop. 120 volt lights, and outlets. 240 volt air compressor and stick welder. Buried another 100 feet of the 2-2-4 to the house. That was close to 18 years ago. Never had any problems.
Here, the 120 volt are put on each leg, they cancel each other out on the return or neutral. So unless all load on one leg,,, and NO 220 volt, the 222 would be needed... If there are a fair amount of 220 and the 120 load is staggered, then 224 will be fine. Other power systems may be different. But heaters,, stoves, dryers, ac's, water heaters and other large appliances are all 220 volt and put NO load on the neutral. Those appliances make up almost 50 percent of the load. And some places have 220 volt lighting. Of course 3 phase will require more wires and be different. Your power system could be different. I would suspect the usage of your power system will dictate the final design.
Dune Country
Well-known Member
Changed a breaker in our rv park back in november, big no no I guess, PUD came and pulled the meter and would not replace it until those 27 sites were brought up to code.
Had to bury 2/2/2 and/2 4th wire was for equipment ground,wouldn't just let me add ground rods, 1000' overall
Had to bury 2/2/2 and/2 4th wire was for equipment ground,wouldn't just let me add ground rods, 1000' overall
Having been an electrical power distribution engineer in different jurisdictions, I can tell you when and where to use say 222 or 224 ITS WHICHEVER THE LOCAL JURISDICTION SAYS YOU USE and certainly NOT what I or anyone here (Including Billy Bob and Bubba) may say or think. On typical 120/240 Volt Single Phase Three Wire residential service if it happened one leg of 120 was full loaded and there were no 120 volt loads on the other leg, THE NEUTRAL WOULD BE CARRYING THE SAME CURRENT AS THE HOT LEG, however if both legs of 120 volt carried the same current THERE WOULD BE NO NEUTRAL CURRENT (possibly subject to harmonics).
When I practiced engineering just to be on the safe side when I didnt know the load distribution I would NOT derate the Neutrals ampacity even if the NEC or local inspectors may have allowed it. Better safe then sorry I figured and no one or inspectors complained.
Now yall do as you please, its your money and your choice and you get no argument from me.
John T Long retired EE and rusty on the NEC so no warranty, I can only report how I did it where I practiced, do as you like
When I practiced engineering just to be on the safe side when I didnt know the load distribution I would NOT derate the Neutrals ampacity even if the NEC or local inspectors may have allowed it. Better safe then sorry I figured and no one or inspectors complained.
Now yall do as you please, its your money and your choice and you get no argument from me.
John T Long retired EE and rusty on the NEC so no warranty, I can only report how I did it where I practiced, do as you like
Under the old NEC it was permissible to run 3 wires Hot Hot Neutral from a main home panel out to a sub panel for 120/240 Single Phase Three Wire Service. HOWEVER several years ago the NEC required 4 wires Hot Hot Neutral Ground out to MOST 120/240 sub panels and at the sub the Neutral and Ground (unlike at main) ARE NOT BONDED AND SEPARATE. It would take too much typing to explain why 4 is better and safer and that's beyond the scope here. I cant explain in a paragraph what takes entire books or chapters to explain or why the NEC made the change, but generally they make changes to save a life or prevent a fire.
OF COURSE THERE ARE THOUSANDS OF THE OLD THREE WIRE SYSTEMS AND YES THEY WORK FINE WELL DUH
I'm ONLY describing the latest code and practices but yall feel free to do as you please, its your home your money and your risk not mine lol
John T Retired Electrical Engineer
OF COURSE THERE ARE THOUSANDS OF THE OLD THREE WIRE SYSTEMS AND YES THEY WORK FINE WELL DUH
I'm ONLY describing the latest code and practices but yall feel free to do as you please, its your home your money and your risk not mine lol
John T Retired Electrical Engineer
pat sublett
Well-known Member
The neutral is part of the circuit on 120v.Unless all of the load is 220v, it doesn't make sense to use a smaller neutral. In reality, if all of the load is 110v, although the codes never require it, the neutral should be bigger than the 120 leads.
huntingreen2day2
Member
Not if installed properly. 2 2 4 is fine. Downsizing the neutral is perfectly legal.
huntingreen2day2
Member
You have no idea what you are talking about. Properly installed 110 v0lt circuits there will be very little load on the neutral wire.
MarkB_MI
Well-known Member
- Location
- Motown USA
You don't mention the length of the run. If it's a short run, say 20 feet, then the difference in voltage drop (in the case of an unbunbalancedalanced load) between 2 and 4 guage will be negligible. But if it's a long run, say 100 feet or more, it's probably worthwhile to go with 2 gauge just to reduce potential voltage drop.
As far as ampacity goes, you can easily figure out your worst-case scenario by looking at your circuit breaker panel. Add up the sizes of your circuit breakers on each leg. If, for example, you have four 15 amp breakers on one leg and five 20 amp breakers on the other, that means you'll never have more than 60 amps load on one leg and no more than 100 on the other. 4 gauge URD has an ampacity of 85 amps (in conduit), so the 100 amp leg could potentially cause an overcurrent in a 4 gauge neutral. But by moving one 20 amp breaker to the other leg, you would bring both legs down to 80 amps, which a 4 gauge neutral can safely handle.
As far as ampacity goes, you can easily figure out your worst-case scenario by looking at your circuit breaker panel. Add up the sizes of your circuit breakers on each leg. If, for example, you have four 15 amp breakers on one leg and five 20 amp breakers on the other, that means you'll never have more than 60 amps load on one leg and no more than 100 on the other. 4 gauge URD has an ampacity of 85 amps (in conduit), so the 100 amp leg could potentially cause an overcurrent in a 4 gauge neutral. But by moving one 20 amp breaker to the other leg, you would bring both legs down to 80 amps, which a 4 gauge neutral can safely handle.
Switchflicker
Member
Could you explain this please. I always thought the neutral (white wire) was part of the whole 110 volt circuit. Thanks
In a single phase circuit 120/240 volt there
are 2 power legs that we'll call A phase and
B phase. If there is a 10 amp 120 volt load
on phase A then there is also a 10 amp load
on the neutral. However if you add a 5 amp
load onto phase B then the neutral load is
only 5 amps because the neutral carries the
difference if the 2. If you try to balance
your loads between A phase and B phase then
there is very little load on the neutral.
However if you put all the load on one phase
then the neutral carries the same amount of
load and if the neutral is smaller it can
overheat because it is not capable of
carrying as many amps.
In order for this to be an issue with
2/2/4 under you would have to have in excess
of 60 amps on the neutral on a circuit
designed to handle 100 amps. It is a pretty
inconceivable idea to have accidentally
happen. It would mean using every other
breaker space for your 120 volt loads. It is
more likely to happen with 15-30 amp loads.
are 2 power legs that we'll call A phase and
B phase. If there is a 10 amp 120 volt load
on phase A then there is also a 10 amp load
on the neutral. However if you add a 5 amp
load onto phase B then the neutral load is
only 5 amps because the neutral carries the
difference if the 2. If you try to balance
your loads between A phase and B phase then
there is very little load on the neutral.
However if you put all the load on one phase
then the neutral carries the same amount of
load and if the neutral is smaller it can
overheat because it is not capable of
carrying as many amps.
In order for this to be an issue with
2/2/4 under you would have to have in excess
of 60 amps on the neutral on a circuit
designed to handle 100 amps. It is a pretty
inconceivable idea to have accidentally
happen. It would mean using every other
breaker space for your 120 volt loads. It is
more likely to happen with 15-30 amp loads.
dr sportster
Well-known Member
The neutral cancels current only when the 3 wires have the breakers properly staggered in the panel. Sloppy placement of wires landed on breakers leaving a neutral handling phase B and B , or A and A, 3 wire circuit, then the neutral will overload. Must be two different phases per neutral.
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