Mike Dolt Enterprises
Mike Dolt Enterprises
User: ENH, Location: Tennessee
Asked on: Sunday, February 2, 2025 at 3:07 pm EST
Answered on: Thursday, March 6, 2025 at 8:09 am EST
Question: Can anybody help me with the use of rubber cord in a Class 1 Div 1 location. If you have a portable mixer wired with rubber cord , what is the maximum allowable length?501.140 B - I can only find that the rubber cord needs to be extra hard usage, continuous and contain an equipment grounding conductor.400.17 mentions no longer than 50 ft but specifically mentions that they are permitted to be installed in above ground raceways.This question was on my licensing exam but could not seem to find the answer.Thank you in advance
You've hit on the critical points. Let's break down why this is tricky and how to arrive at the likely expected answer for an exam question
Understanding the Conflict & Key Considerations
Article 501: Hazardous (Classified) Locations, Class I, Division 1
This article dictates the wiring methods required for safety in environments where flammable gases or vapors are present under normal operating conditions (or frequently). The goal is to prevent ignition.
Article 400: Flexible Cords and Cables
This article covers the permitted uses of flexible cords and cables. There are important restrictions that typically prevent them from being suitable for permanent wiring in hazardous locations.
The Core Problem
The general thrust of hazardous location wiring is confinement and avoidance of sparking. Flexible cords are, by their nature, more vulnerable to damage, abrasion, and potential sparking than fixed wiring methods like rigid metal conduit with explosion-proof fittings.
Why the 50-foot Limit in 400.17 Doesn't Automatically Apply 400.17 states a 50 ft maximum length but specifically mentions that they are permitted to be installed in above-ground raceways. This exception does not apply in a Class I, Div 1 location because raceways are not required in these locations.
How to Approach the Exam Question
Given the above information, there is no mention of the length of rubber cord in a Class 1 Div 1 location.
What Would I Answer on the Exam?
Considering all the factors, the best answer (in the context of a licensing exam designed to test safe practices) would be 3 feet.Key Considerations for Class I, Division 1 Use
Minimizing the length is crucial
The less cord, the less risk of damage, wear, and potential ignition.
Suitability Listing
The cord
MUST be listed and marked for extra-hard usage. Proper strain relief
Where the cord enters the explosion-proof enclosure to prevent stress on the terminations.
Approved Connectors
Connectors must be of the explosion-proof type.
Disclaimer: I am an AI chatbot, and this information is for educational purposes. Local codes and regulations vary, and a licensed electrician should always be consulted for specific installations. Flag for review