Do you have molten solder you use for plumbing repairs and want to use it for a minor electrical repair that involves welding? Many people assume that solder can be used almost universally in any situation.
Plumbing solder will probably do a similar job as electrical solder, right? No. Do NOT use plumbing solder for your electrical wires.
In this PlumbingNav guide, we will cover:
What to know about the conductivity of plumbing solder
Plumbing solder vs. electrical solder
How to apply plumbing solder
What's In This Guide?
What To Know About the Conductivity of Plumbing Solder
Is Plumbing Solder Conductive?
The answer is no. Plumbing solder is not considered a highly conductive material.
Conductivity refers to a material’s ability to transmit energy, such as heat or electricity. While thermal conductivity and electrical conductivity are closely related, they are technically distinct. With that being said, most thermal conductors also work well as electrical conductors with a few exceptions.
Conductivity depends on numerous factors, especially the materials used in the solder. Silver and copper offer the most conductivity at ratings of 100 and 97, respectively.
Plumbing solder should not be used for electrical wiring because it can deteriorate under electrical conditions, leaving wiring exposed. If you need to do some electrical wiring, make sure to use electrical solder.
Plumbing solder and electrical solder are not interchangeable.
Plumbing Solder Basics
Solder is a metal alloy that is used to join two pieces of metal together when plumber’s tape and pipe dope simply won’t do.
Solder often comes in the form of solder wire or solder paste, depending on your particular needs.
Solder melts using a torch or soldering iron and then is allowed to cool, forming a strong bond between the two pieces of metal, preventing plumbing leaks.
While primarily used for metal, such as stainless steel and copper tube, you can also solder plastic material for art projects and other superficial applications. However, you should not solder PEX pipe, ABS pipe, or PVC pipe.
Types of Solder
There are different types of solder, each with its own melting point and composition, although one type of solder is not necessarily mutually exclusive from the others.
The different types of solder include:
Soft solder (lead solder or leaded solder)
This solder has a low melting point that can work with a soldering iron and advanced strength. However, it does contain lead, which cannot be used in potable water systems.
Lead-free solder
In accordance with Section 1417 of the Safe Drinking Water Act (SDWA), lead-free solder contains less than .25% lead. It has a higher melting point that usually requires a torch as opposed to a soldering iron.
Silver solder
Silver solder includes silver to prevent silver migration. You can find leaded and lead-free silver solder.
Rosin core solder
Rosin core solder refers to a solder tube that contains a gentle rosin flux, which is resistant to corrosion and doesn’t leave behind much residue. It’s also appropriate for fragile materials, such as aluminum. Rosin core solder generally takes longer to heat. Finally, it can emit toxic fumes when melted.
Acid core solder
The acid core consists of a solder tube filled with a harsh acid flux core. It dissolves oxidation and grease on the material before melting, extremely important in plumbing practices. Suitable for stainless steel and copper but not aluminum. Highly corrosive. Not conducive since the acid core creates a barrier that prevents conductivity.
Did You Know? Rosin solder can cause hazardous conditions. Exposure to rosin can cause eye and respiratory irritation, nose bleeds, and headaches. When working with rosin solder, always wear the proper protective gear.
Plumbing Solder Vs. Electrical Solder
There are numerous differences between plumbing solder and electrical solder. While the differences may appear minor at first, they provide the qualities that make each solder ideal for its intended purposes (and not ideal for other purposes).
Plumbing solder is an alloy that is composed of lead and tin, while electrical solder is a solder alloy that is composed of lead and silver.
Plumbing solder has a higher melting point, so it requires the heat from a gas torch. Electrical solder has a lower melting point than plumbing solder, so it can melt with a simple soldering iron. Soldering irons generate less heat and are generally considered safer and easier to use than a gas torch.
Most plumbing codes require solder applied to potable water systems to be lead-free. Electrical solder may contain lead.
Both solders use a soldering flux in the installation process to prevent oxidation and promote bonding. Plumbing solder uses an acid-based flux, which can succumb to galvanic corrosion more quickly than the rosin core flux used in electrical solder. When used for electrical wiring, plumbing solder may deteriorate and leave the wire exposed, causing a fire hazard.
How to Perform Plumbing Soldering
If you’re planning on doing some DIY plumbing that involves creating a strong connection between two metal pipes, you’ll need to know how to use plumbing solder.
This step-by-step guide will show you everything you need to know about the soldering process.
Before you begin work, ensure you have the proper soldering iron kit and a steady, level metal surface. Always read the instructions regarding your soldering iron kit thoroughly, especially the safety protocol.
First, cut the end off the solder roll and tin the tip of the iron by touching it to the solder.
Next, apply heat to the solder joint and feed in the solder. Keep the iron in contact with both the pipe and the solder as you work.
Once the joint is filled, remove the iron and allow the solder to cool for a few seconds. You’ll know it’s properly cooled when it’s solid and shiny.
Finally, give the joint a quick once-over with a wet sponge to remove any excess flux residue.
See the video below to learn more about how to solder copper pipe:
Frequently Asked Questions About If Plumbing Solder Is Conductive
Is plumbing solder the same as electrical?
No. Plumbing solder uses an acid-based flux, while electrical solder uses a rosin flux. An acid-based flux isn’t durable enough to protect electrical wiring due to its corrosive properties, potentially causing a fire hazard when used for electrical purposes. Furthermore, plumbing solder contains less conductive materials.
What kind of solder do you use for copper pipes?
For copper tubing, use lead-free acid-based flux solder. Verify on the packaging that the solder is made for a copper pipe before you begin.
Can soldering be illegal?
If you use lead solder in potable water systems, lead-based solder can be illegal and dangerous to your family’s health. Check local building codes if you have specific questions.
You also don’t want to perform electrical soldering on wires attached to your home’s electrical circuit without the proper permit. However, you can use electrical solder for circuit boards on your computer or for advanced crafting projects.
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We write about “all things plumbing,” helping you navigate common questions, repairs, and the best plumbing products on the market.
