Is it permissible to have a 30 amp breaker on a 12-2 NM-B that controls a well? Not sure if I can follow the same rules as Hvac equipment that has high start up amps. I am told that the well in question has a running amps of 13.1 and a start up of 26.2. The well contractor is saying it needs a 10-2 (30 amp minimum). Is this correct?
Well breaker and wire size
- Thread starter crtemp
- Start date
- Status
No. Just says 2hp
- Location
- New Jersey
- Occupation
- Journeyman Electrician
2 HP motor from T430.248 has an ampacity of 12 amps at 230 volts. Maximum size OCPD for inverse time CB from T430.52 is 250%.
12 amps * 125% = 15 amps for the conductors
12 amps * 250% = 30 amps for inverse time CB
Minimum conductor size #14, max OCPD 30 amps.
12 amps * 125% = 15 amps for the conductors
12 amps * 250% = 30 amps for inverse time CB
Minimum conductor size #14, max OCPD 30 amps.
I can put a 12-2 nm-b on a 30 amp ocpd?
Last edited:
Dzboyce
Senior Member
- Location
- Royal City, WA
- Occupation
- Washington 03 Electrician & plumber
Most pump installers do not use the NEC tables for wire size or motor amperage. They use tables published by the Pump Manufacurers.
Here is Franklin Electric’s AIM Manual. http://www.franklinwater.com/media/110562/M1311_60_Hz_AIM_12-14-WEB.pdf
Other submersible motor manufacturers publish their own manuals.
These wire sizing charts allow for voltage drop.
from the Franklin manual, service factor amps for a 2 hp 230v 1 phase submersible motor are 13.2 amps. Table 11 gives the maximum length of wire to stay under a 5% voltage drop. For the 2 hp motor #14 wire is good for up to 150 ft, service entrance to motor. #12 wire is good for 250 ft. And #10 wire is good for a maximum distance of 390 feet.
table 14 says to use a 25 amp circuit breaker.
starting amperage will be 4-6 times fla or in the area of 50-60 amps. That’s where my data logger shows starting amperage when I’ve used it on a 2 hp pump.
Here is Franklin Electric’s AIM Manual. http://www.franklinwater.com/media/110562/M1311_60_Hz_AIM_12-14-WEB.pdf
Other submersible motor manufacturers publish their own manuals.
These wire sizing charts allow for voltage drop.
from the Franklin manual, service factor amps for a 2 hp 230v 1 phase submersible motor are 13.2 amps. Table 11 gives the maximum length of wire to stay under a 5% voltage drop. For the 2 hp motor #14 wire is good for up to 150 ft, service entrance to motor. #12 wire is good for 250 ft. And #10 wire is good for a maximum distance of 390 feet.
table 14 says to use a 25 amp circuit breaker.
starting amperage will be 4-6 times fla or in the area of 50-60 amps. That’s where my data logger shows starting amperage when I’ve used it on a 2 hp pump.
Here is my situation...
I have a 12-2 going from the panel to the conduit that goes to the well head. Total length of the 12-2 is roughly 40 feet. This is where my job ends. The well contractor does all wiring and connections from this point on. He is insisting on it having a 30 amp breaker rather than the 20 amp breaker that I supplied. From what I'm told the conduit from the house to the well head is 50 feet and the well is 640 feet deep.
ptonsparky
Tom
- Occupation
- EC - retired
Yes, but RTFineM for the pump motor. Installation instructions are the first source.
RTFineM?
Dzboyce
Senior Member
- Location
- Royal City, WA
- Occupation
- Washington 03 Electrician & plumber
You and I are both located in Washington state. I am assuming that this installation is also in Washington. Washington state requires that pump installers be licensed electricians. We are also licensed plumbers, but that’s another story.
If the pump installer extends any wiring beyond the well head, he must obtain an electrical permit separately and in addition to the electrical permit you have obtained. His work is inspected separately from yours.
he had told you what his requirements are for you portion of the work. This is the second time you have posted this question. Why are you fighting what the other electrician has told you what he needs? If he is installing a VFD, #10 wire may be the smallest size wire allowed by the manufacturer.
My advice? Replace your #12 with #10 now, before you get a correction notice from labor & industries. If you bid it as #12, submit a change order to the owner. What specifications did the owner give you? Had the pump been selected at that time? Did the owner have the specifications from the pump installer when he gave you your specifications, or were there assumptions made?
If the pump installer extends any wiring beyond the well head, he must obtain an electrical permit separately and in addition to the electrical permit you have obtained. His work is inspected separately from yours.
he had told you what his requirements are for you portion of the work. This is the second time you have posted this question. Why are you fighting what the other electrician has told you what he needs? If he is installing a VFD, #10 wire may be the smallest size wire allowed by the manufacturer.
My advice? Replace your #12 with #10 now, before you get a correction notice from labor & industries. If you bid it as #12, submit a change order to the owner. What specifications did the owner give you? Had the pump been selected at that time? Did the owner have the specifications from the pump installer when he gave you your specifications, or were there assumptions made?
- Occupation
- Licensed Electrician
Read the effen manual. AKA, read the instructions.
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
Is that 12-2 NM that is in the conduit?
Is the conduit going outside?
If yes to both of these you can't use the 12-2 anyway.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Outside of voltage drop considerations - infinity just told you you could have 14 AWG conductors and 30 amps circuit breaker If you jumped to a 3 hp motor you could possibly have 12 AWG protected by a 45 amp breaker - again before considering voltage drop.
The 12-2 is not in conduit. I’m assuming the well contractor is switching to THHN through the conduit.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
NM cable portion(s) of circuit would need to use 60 C ampacity THHN/THWN can use 75 C ampacity unless terminations are not marked 75C (but they likely are).
240.4(D) doesn't apply to motor circuits so you are not limited to 20 amp breaker on 12 AWG for such circuit.
- Status