Sparky’s
CircKit.

Our Pipe Fill Calculator is one of the most popular tools in Sparky’s CircKit, so we’ve given it a big update. One of the most requested features has arrived: support for multiple insulation types in a single calculation.

But that’s just the beginning.

The updated tool features our new step-based interface, following the same intuitive flow used in our Hazardous Locations, Transformers, and Motors tools. When you open the calculator, you’ll first choose between the Basic (classic) interface or the new Advanced interface. For this walkthrough, we’ll focus on the Advanced mode — the Basic mode remains unchanged, except for inline derating, for those who prefer simplicity.

As of right now, this is only available on iOS, but will be available to Android users in the coming months.

Step 1: Select Conduit Type and Ambient Temperature

Start by choosing your conduit type (EMT, PVC, Rigid, etc.). Next, select the ambient temperature for your installation. This ensures accurate derating when adding conductors in the following step.

Step 2: Add Insulation Types

You’ll then be prompted to add all insulation types that will be pulled into the conduit.

Step 3: Add and Adjust Wires

Once you’ve selected your insulation types, you’ll see them listed on the next screen.

Tapping an insulation name expands a dropdown menu of all available wire sizes (for example, T90 Solid supports 14–10 AWG, while T90 Stranded supports 14 AWG–1000 KCM).

Use the +/- buttons to add or remove wires. As you build your run, Sparky’s CircKit automatically derates the ampacities using Table 5, accounting for both ambient temperature and wire count.

You can toggle between copper and aluminum by tapping the coloured circle beside each entry. To keep things consistent, the tool uses the 75 °C column of Tables 3 and 4. When finished, simply tap Next.

Step 4: Review Results

Your results screen displays the recommended conduit size along with fill percentages and colour indicators:

• Green — within code limits
• Orange — within 5% of the limit
• Red — over the limit

For example, running a single 750 KCM RW90 Stranded Unjacketed 600 V conductor through EMT will show:

• 1¼″ = Red (72%)
• 1½″ = Orange (52.75%)
• Larger sizes = Green

Sparky’s CircKit automatically adjusts the code limits based on the number of conductors — 53% for single, 30% for two, and 40% for three or more.

Step 5: Save and Reuse

You can tap the “Save as Note” icon to store any calculation for later, and even tag it to a job for quick access (stay tuned for more details in our next post).

Give the new workflow a try and let us know what you think.

If you’re an electrician, you’ve probably memorized the first four wire ampacity tables by now — or at least worn them out from constant use. Our wire ampacity tool puts all that information right at your fingertips without the page flipping. Just pick your insulation temperature rating, whether you’re using copper or aluminum, and if it’s in free air or a raceway. No more juggling code books or hunting for the right table.

But here’s where this tool really saves the day: derating calculations. We’ve all been there — bouncing between tables 1 through 5, scribbling numbers on whatever scrap paper we can find, trying to keep track of correction factors. It’s tedious and easy to mess up when you’re in a hurry.

Now it’s dead simple. Just tell the tool how many current-carrying conductors you’ve got in your raceway and what the ambient temperature is. The calculator does all the heavy lifting — applies the right correction factors and gives you the final ampacity. No more mental math, no more wondering if you grabbed the right factor from the right table.

It’s quick, and it cuts out the small math mistakes that can cause bigger problems later.

Our pot light spacing calculator is hands down our most popular feature. In fact, it’s been such a hit that we turned it into its own app — Lumen Layout — so electricians everywhere can use it. The tool gives you two ways to work: basic mode for quick jobs and advanced mode when you need more control.

Basic Mode: Fast and Simple

Basic mode gets you in and out fast. Just plug in your room size, pick how you want to arrange the lights (one row, two rows, square pattern, etc.), and tell it how many lights you’re installing. Hit calculate and you’re done — you’ll get the exact spot for each light, a diagram showing the layout, and all the spacing measurements. Perfect for those straightforward jobs where you need answers now.

Advanced Mode: Full Control

Advanced mode gives you the steering wheel. Instead of just three settings, you get five. You decide exactly how many lights go along the length and width of the room — no preset patterns to limit you.

The most useful part is how it handles shoulder spacing (that’s the distance from your first light to the wall). You get three options:

• Equal spacing: Same distance everywhere, wall to light and light to light
• Default spacing: Uses half the light spacing for the shoulder — the way most electricians do it
• Custom spacing: Set your own distances for those tricky jobs

Whether you’re doing a quick kitchen install or mapping out a complex commercial space, this calculator handles both.

Every electrician has been there. You’re on site, you need a quick voltage drop calculation or a motor size, and you’re either flipping through the code book or using a basic calculator that isn’t built for electrical work. After enough hours of doing calculations by hand, I decided to build the app I wanted. That’s Sparky’s CircKit.

It puts the things we use every day in one place: motor and transformer sizing, voltage drop, wire derating, reference tables and more. It’s made for electricians in the field, but contractors and engineers will find it useful too.

In this blog series, I’ll walk through the different tools and calculators, and cover new features as they come out.

If you have suggestions or requests, email us at software@thesparky.work.