If you are currently weighing a close nipple vs chase nipple for a project, the biggest mistake you can make is assuming they are interchangeable just because they're both short pieces of threaded metal. They might look like cousins from a distance, but in the world of plumbing and electrical work, they serve completely different masters. One is designed to move fluids or gas through a tight space, while the other is mostly about connecting electrical enclosures without taking up a ton of room inside the box.
Getting the two mixed up isn't just a minor inconvenience. Using the wrong one can lead to leaks in a plumbing line or a code violation in an electrical setup. Let's break down exactly what makes these two components tick and how you can tell them apart when you're digging through a bin at the hardware store.
What Exactly Is a Close Nipple?
In the plumbing world, a nipple is just a short length of pipe with male threads on both ends. A close nipple is the shortest version of that pipe you can possibly get. In fact, it's so short that there is no unthreaded space between the two ends. When you screw a close nipple into two different female fittings, those fittings will end up nearly touching each other.
The main thing to remember about a close nipple is that the threads run the entire length of the piece. Because of this, you usually can't even see the nipple itself once everything is tightened down. It disappears into the joint. These are staples in gas lines, water heaters, and various industrial piping setups where you don't have the luxury of extra space.
You'll usually find these made of brass, galvanized steel, or black iron. Because they are designed to be airtight or watertight, they use tapered threads (NPT). As you screw the nipple into a fitting, the threads get tighter and tighter, creating a seal that can hold pressure. If you try to use one of these for electrical work, you'll quickly find that it doesn't play nice with locknuts because of that taper.
Understanding the Chase Nipple
Now, let's look at the chase nipple. If you ask an electrician for a nipple, this is probably what they'll hand you. Unlike the close nipple, which is a hollow tube of threads, a chase nipple has a very distinct "head" or flange on one end. It looks a bit like a hollowed-out bolt.
The purpose of a chase nipple is to connect two electrical boxes together or to connect a box to a piece of conduit. You slide the threaded end through a knockout hole in the box, and that flange (the "head") stays on the inside, acting as a stop. Then, you spin a locknut onto the threads from the other side to secure it.
The "chase" part of the name actually refers to the fact that it creates a smooth path—a "chase"—for wires to pass through without getting snagged on sharp edges. Most chase nipples have a smooth, rounded interior throat specifically to protect wire insulation. You'll see these made of zinc-plated steel, aluminum, or sometimes plastic (PVC) for non-metallic setups.
Key Differences in Threading and Design
The most technical difference in the close nipple vs chase nipple debate comes down to the threads. As mentioned, close nipples for plumbing almost always use tapered threads. This is vital for preventing leaks. If the threads were straight, the water or gas would just spiral right out of the joint unless you used a massive amount of sealant.
Chase nipples, on the other hand, often use straight threads (NPS). Since they aren't meant to hold back pressurized liquid, they don't need that wedge-like seal. The threads just need to hold a locknut tight against the side of a metal box. If you tried to put a plumbing locknut on a tapered close nipple, it would eventually get stuck halfway down or sit crooked because the diameter of the nipple is changing as you go.
Another visual giveaway is the "shoulder." A close nipple has no shoulder. It's just a cylinder of threads. A chase nipple has that wide, flat hex-shaped or circular head. You can actually grip a chase nipple with a wrench on that head, whereas with a close nipple, you usually have to use a specialized internal pipe wrench or just be very careful with your pliers so you don't crush the threads.
When to Use a Close Nipple
You should reach for a close nipple when you are working on any fluid or gas transport system where space is at a premium. A common scenario is when you're installing a pressure gauge or a bypass valve. If the two valves need to be as close as possible to keep the footprint of the machine small, the close nipple is your best friend.
It's also common in: * Boiler headers: Connecting various sensors and outlets in tight clusters. * Gas manifolding: Linking regulators to shut-off valves. * Decorative piping: People who make furniture out of black iron pipe love close nipples because they make the joints look seamless.
Just a heads-up: installing these can be a bit of a pain. Since there's no "blank" space to grab with a pipe wrench, you risk marring the threads. If you're working on a high-pressure system, even a small scratch on those threads can cause a slow leak that's a nightmare to fix later.
When to Use a Chase Nipple
If you're doing electrical work, the chase nipple is almost always the correct choice over a plumbing nipple. It's specifically designed to meet NEC (National Electrical Code) requirements for wire protection. If you were to use a standard close nipple to connect two electrical boxes, the rough, cut edges of the pipe could easily slice through wire insulation over time as the building vibrates or as wires are pulled through.
Chase nipples are perfect for: * Back-to-back box connections: When you have two outlets on opposite sides of a wall and you want to run wire directly between them. * Connecting a box to a transformer: The chase nipple keeps the connection short and tidy. * Creating a "hub" for conduit: When used with a threaded hub, it provides a very secure, grounded connection.
Most modern chase nipples also come with a "plastic throat" or an insulated liner. This is a bright blue or yellow plastic ring inside the nipple that makes it impossible for the wires to touch the metal edge. This is a huge safety feature that a standard plumbing close nipple just doesn't have.
Can You Use One for the Other?
In a pinch, people sometimes try to swap them, but it's rarely a good idea. Can you use a close nipple in an electrical box? Technically, yes, if you use it with two conduit bushings to protect the wires. But it's bulky, it's harder to tighten, and it's usually more expensive than a simple zinc chase nipple.
Can you use a chase nipple for plumbing? Absolutely not. It will leak. The straight threads and the flange aren't designed to create a gasket-like seal. Even if you buried it in Teflon tape and pipe dope, the pressure of a standard home water line would likely find a way through. Plus, the materials used for electrical chase nipples (like pot metal or zinc) aren't always rated for constant contact with water and can corrode or leach chemicals into your supply.
Material Choices and Durability
When you're choosing between a close nipple vs chase nipple, you also need to think about the environment. * Galvanized Steel: Great for plumbing where rust is a concern, but also common in heavy-duty industrial electrical work. * Brass: The gold standard for water lines. It's soft enough to get a great seal but tough enough to last decades. You rarely see brass chase nipples because they'd be unnecessarily expensive for an electrical box. * Zinc Die-Cast: This is what most hardware store chase nipples are made of. It's light, cheap, and doesn't rust, but it's brittle. If you hit it too hard with a hammer, it'll snap. * Stainless Steel: You'll find both types in stainless for food-grade or highly corrosive environments (like a chemical plant or a brewery).
Summary of the Choice
At the end of the day, the close nipple vs chase nipple decision comes down to what's going through the middle. If it's water, gas, or steam, you want the close nipple with its tapered threads and "all-thread" body. If it's copper wire, you want the chase nipple with its protective flange and smooth interior throat.
Knowing the difference might save you a trip back to the store, but more importantly, it ensures that your project stays up to code and leak-free. Just remember: if it looks like a tiny pipe, it's a close nipple. If it looks like a hollow bolt with a head on it, it's a chase nipple. Simple as that!