Mike Dolt Enterprises
Mike Dolt Enterprises
User: ctaylo360860, Location: colorado
Asked on: Monday, August 11, 2025 at 7:03 pm EDT
Answered on: Monday, August 11, 2025 at 7:08 pm EDT
Question: Hi I'm hoping i can get some help with clarifying the violations of an existing install and gain some more understanding of 502 hazardous locations class II division 1 of the nec.The company I am work for has an existing motor for a sweep auger wired inside of a grain bin that’s filled with corn. The auger doesn’t run or receive power until the motor is exposed and the bin can be entered into. there are no prints or classifications that I'm aware of , but in my opinion this still seems to be a class II division 1 environment. see photos 1-6here are the violations I found with the previous electricians install.1. the current install has motor that doesn't seem to be rated for class II division 1 environment and is a violations of 502.125(a)2 the motor has a male L19-30p plug installed on it, they then run 14-4so cord into the bin with a L19-30p plug that is hooked to a starter on the outside of the bin.this seems to violate 502.140 (b)(4) as the so cord is terminated using normal so cord connectors and need to be listed for the location. also 502.145 as the twist locks are not listed for the class II division 1 environment see photos 1-6if I understand nfpa 60 chapter that is is the owner/operator of facility with potentially combustible dust shall be responsible for determining whether the materials are combustible or explosive, and if so, for characterizing the properties as required to support the dha (625:5,11my plan is to order a new motor that is meant to be inside of a class II division 1 environmentrun so cord to the new motor using listed dusttight so cord connectors and get the twist lock outside of the class II division I environment. the fittings im looking at using may not be this exacts size gut should have the same rating. see photos 9&10photos 7& 8 are from the manufacturer and are showing how they have the existing set up wired. the only difference is that they have male twist lock plugs installed on the motors and are running female twist lock receptace into the bin and pluging them in, instead of running the so cord to the motors j box.I hope this makes sense i wrote this at the end of the day in a hurry. if there are any questions please ask and i will clairify my best. again appreciate any and all helps thanks !
Okay, let's break down your observations and plan for this Class II Division 1 hazardous location. You're on the right track with your analysis and proposed solutions.
Confirmation of Violations & Concerns
You are correct in identifying the following violations:1. Motor Not Rated for Class II Division 1 (502.125(A)): This is the most significant violation. A standard motor is a potential ignition source due to arcing in the windings, brushes (if it's not an induction motor), and surface temperatures.2. Non-Listed Cord Connectors (502.140(B)(4)): Standard SO cord connectors are not acceptable in Class II Division 1 locations. They are not dust-tight and can allow combustible dust to accumulate inside the enclosure, potentially leading to ignition.3. Non-Listed Twist-Lock Receptacles/Plugs (502.145): Similar to the cord connectors, the twist-lock devices used must be specifically listed and rated for Class II Division 1. They need to be dust-tight and prevent arcing in the presence of combustible dust.
4. Flexible Cord Usage
Consider the application and location. Is the use of flexible cord permitted as per 502.140(A) and 400.7?
NFPA 61 & Responsibility
You are correct about the owner/operator's responsibility. NFPA 61 (not 60) is the relevant standard for agricultural and food processing facilities. It requires the owner/operator to determine if combustible dust hazards exist and to characterize those hazards through a Dust Hazard Analysis (DHA). The DHA is crucial for defining the Class and Division of the hazardous location. Without it, you're making a best guess, but it needs to be formalized. You should strongly advise the company to conduct a DHA. This is not just a code compliance issue; it's a safety issue. Document your advice in writing.
Proposed Solution & Refinements
Your plan is generally sound, but let's refine it:1. Class II Division 1 Motor
Absolutely necessary. Make sure it's rated specifically for Class II, Division 1, Group G (grain dust). Verify the T-code (temperature rating) is appropriate for the specific grain. The motor nameplate will have this information.2.
Dust-Tight Cord Connectors
The connectors you linked (Photos 9 & 10) appear to be the correct type – dust-tight, suitable for flexible cord, and designed for hazardous locations. Verify they are listed and labeled for Class II, Division 1. Ensure you are using the correct size for the cord you select. Install them properly, paying close attention to sealing.
3.
Moving the Twist-Lock
Excellent plan. Getting the twist-lock connector outside the Class II, Division 1 area is the ideal solution.4.
Cord Selection
14/4 SO cord is generally fine from a current-carrying capacity standpoint (verify that the motor's full-load amps are within the cord's rating). However, ensure the cord is also rated for the environment and is suitable for the mechanical stresses it will encounter. Look for "Hard Usage" ratings and resistance to abrasion, oils, and chemicals that might be present. SOW, SOOW, or similar rated cords would be more appropriate. The key is to choose a cord that is durable and resistant to the conditions in the grain bin.5.
Manufacturer's Wiring (Photos 7 & 8)
The manufacturer's wiring scheme is also likely a violation unless those twist-lock plugs/receptacles are specifically listed and labeled for Class II Division 1 locations. The fact that they are doing it doesn't make it compliant.6.
Bonding
Make sure all metal parts of the system are properly bonded and grounded, including the motor, junction boxes, and any metal conduit. This is critical for preventing static electricity buildup, which can be an ignition source. See Article 502.140(B)(3) for information on bonding and grounding.
7.
Overcurrent Protection
Ensure the motor circuit has proper overcurrent protection (fuses or circuit breakers) sized according to the motor's nameplate and the NEC.
Additional Considerations Sealing Fittings
Depending on the installation, you might need sealing fittings where the conduit enters the Class II, Division 1 area. Consult Article 502.15 for sealing requirements. The goal is to prevent dust from migrating out of the hazardous area.
Enclosures
All enclosures in the Class II Division 1 area (e.g., for splices or junction boxes) must be dust-ignitionproof and marked for Class II, Division 1, Group G.
Documentation
Keep thorough documentation of the new installation, including: Motor nameplate information (including Class/Division/Group rating and T-code). Cord connector specifications. Conduit and wiring methods used. Grounding and bonding details. Photos of the completed installation. Ideally, the DHA performed by the owner/operator.
Important Advice Consult a Qualified Professional
Given the potential dangers of combustible dust and the complexities of the NEC requirements, it's highly recommended to consult with a qualified electrical engineer or inspector with experience in hazardous locations. They can review your plan, ensure compliance, and provide valuable insights.
AHJ (Authority Having Jurisdiction)
Check with your local electrical inspector (AHJ) to get their approval on your proposed solution before starting the work. They may have specific requirements or interpretations of the code.
Safety First
Never work in a hazardous location without proper training, PPE (personal protective equipment), and awareness of the potential hazards.
In summary, you've identified the critical violations and are on the right path to correcting them. However, don't underestimate the importance of a formal DHA, proper documentation, and consultation with qualified professionals. Flag for review