Electric Metalic Tubing (EMT), also called thin walls, is a lightweight steel tubing with wall thickness ranging from 0.042′′ for 1/2′′ diameter to 0.0883′′ for 4′′ diameter. While RMC (Rigid Metal Conduit), aka “rigid conduit,” is a heavyweight steel pipe that comes in thicknesses between 0.104″ and 0.225″ (half-inch to four-inch) and 0.266″ for the six-inch tube.
The rigid metal conduit is four times heavier than EMT. It’s more durable and provides more excellent physical protection than the EMT.
Electrical conduits are tubing or other types of enclosures used for protecting individual wires and providing a route for them to travel. A conduit is usually needed when wiring is exposed or if it will get damaged. It’s easy to classify conduits based on what they are made of, how thick the walls are, and how stiff the material is. Its either made up of plastic, coated steel, stainless steel, or aluminum.
This article will give you a detailed overview of the differences between the EMT and RMC.
What Is The Rigid Conduit System?
The Rigid Metal Conduit System is a thick-walled metal conduit, often composed of coated steel, stainless steel, or aluminum.
RMC, or rigid metal conduit, is galvanized steel tubing installed with threaded fittings. It’s mostly made up of the schedule 80 steel pipe. You can thread it using pipe threading equipment. Moreover, you can’t bend RMC with your hands. You would have to use a hickey bender for that purpose.
It is mainly used in outdoor settings to protect the wiring against harsh weather conditions. Its also used to support electric cables, panels, and various other equipment.
You can also use the RMC as a grounding connector, but it’s better to avoid that. One of the significant benefits of the RMC is that it protects sensitive equipment from electromagnetic interference.
What Is An Electrical Metal Tubing (EMT)?
Electrical Metal Tubing (EMT) is a thin-walled tubing, often made of coated steel or aluminum.
The EMT is a thin tubing, so you can’t thread it. It’s also lighter in weight. You can consider it a rigid conduit, but it’s more flexible than other rigid conduit tubings. It can be easily molded with the help of specific equipment.
You can install EMT with the help of benders, couplings, and fittings secured with a set screw. In residential and light commercial construction, it’s usually used for exposed wiring runs. You cannot use it in outdoor or open-air fittings. If you want to use it for outdoor areas, you must fit it with a special water-tight fitting.
Difference Between The Electrical Metal Tubing And The Rigid Conduit
The main difference between both conduits is that of rigidity and thickness. I am presenting these differences in the form of a precise table so that your doubts can get cleared.
| Electrical Metal Tubing (EMT) | Rigid Metal Conduit (RMC) |
| It’s a thin-walled tubing. | It’s a thick-walled metal conduit. |
| It’s light in weight. | It’s four times heavier than EMT. |
| Its diameter ranges from 1/2″ to 4″. | Its diameter might vary from 1/2″ to 4″ to 6″. |
| Its primarily used in indoor and commercial settings. | It’s used in outdoor settings and areas exposed to radiation like atomic reactors, etc. |
| It provides a lesser extent of protection to the wires. | It gives excellent physical protection against external agents. |
| It cannot be threaded. | It can be threaded. |
These are a few of the fundamental differences between both conduits.
Here is a short video about different types of conduits.
Is The Rigid Conduit Stronger Than EMT?
The rigid conduit is pretty strong compared to an EMT due to its increased thickness.
The rigid conduit comprises more thick material like galvanized steel, making it more challenging. This rigidness gives your strength. Its galvanized structure makes it more suitable for use in harsh climates.
In comparison with rigid conduits, the electrical metal conduit is thinly walled. It is easy to handle and install. But it’s not as strong as a rigid metal conduit.
What’s the explosion-proof conduit between RMC and EMT?
RMC and EMT are both explosion-proof, but they aren’t as secure.
The rigid conduit and electrical metal tubing are used for industrial, commercial, and domestic purposes. So there are always chances of hazards due to personal or technical negligence.
If you’re using threaded metal conduit fittings, it cools down the burning gases inside them to a certain extent. In this way, it tones down the severity of an explosion. However, it’s not fully contained, and there’s a chance of spreading.
To avoid gas leakage or restrict explosions, you’ve got to use a highly threaded and galvanized metal conduit. So, in my opinion, the rigid metal conduit is much more explosion-proof than the EMT due to its thickness.
Is EMT Or RMC Better For General Purpose Installations?
The RMC and EMT are both used for general-purpose installation.
It depends on your choice and your budget. RMC will cost you more than EMT as it’s highly galvanized.
You can use both for general-purpose installation. It’s better to use EMT, especially for residential fittings. It’s easy to install and is budget-friendly.
However, if you need a conduit for outdoor fittings, you should opt for Rigid Conduit as it can withstand the calamities of harsh weather.
Can You Use A Bare Ground Wire in The EMT Conduit?
A rule in 250.118(1) says it can be “solid or stranded, insulated, covered, or bare.”
Practically, you want to keep it warm. Copper and steel are two different metals, leading to galvanic corrosion when they come into contact. It also pulls a lot easier through the conduit, so you don’t have a bare wire inside your boxes.
I haven’t seen bare ground inside a pipe before now.
Professionals don’t like it when people use EMT as a ground wire, but the code says that’s OK. People who have seen people use EMT as a neutral wire think it’s also a bad idea.
The conduit breaks, and when an electrician tries to connect it back together, he gets knocked off the ladder. Separate the conductors and pull them apart to do this.
Final Take Away
The main differences between electrical metal tubing and rigid conduit are diameter and wall thickness. Electrical metal tubing is thin, while rigid metal conduit is thick. Its diameter is more as compared to EMT.
You can thread RMC while EMT can’t be incorporated. Rigid conduit is often galvanized, while electrical metal tubing is mainly simple steel or aluminum.
It’s better to use rigid conduits in outdoor or heavy commercial settings. At the same time, you can use Electrical tubing for domestic purposes, primarily in indoor environments.
Both of these conduits have their pros and cons depending on the purpose of their use. You should consult a specialist in the respective field before opting for them.
I hope this article has cleared up your confusion about both of these metal conduits! Check out my other articles on the links below.