The Difference Between Load-Side & Supply-Side Connections: Sean White Explains

The distinction between load-side and supply-side connections is fundamental to solar and energy storage installations, yet the terminology keeps evolving, and the common terms don’t always match what’s actually in the code.

In the video below, HeatSpring instructor Sean White breaks down where these connections occur in relation to your main service disconnect and how the National Electrical Code changed the official terminology in the last code cycle. This quick explainer will help you understand the core concepts behind supply-side and load-side connections – important stuff for any solar professional navigating installations and code compliance.

Ready to master the 2026 NEC? Sean White’s comprehensive 30-Hour 2026 NEC PV, Energy Storage, Building and Fire Codes courses are coming out soon on HeatSpring or enroll immediately in Sean’s 30-Hour 2023 NEC course.

Transcript below.

A lot of people ask me, what’s the difference between a supply-side and a load-side connection? And it’s pretty simple.

You have a utility meter, you have a main service disconnect – a lot of times people just call it the main breaker – and you have all the loads on the load side. That means the side that all of your stuff in your building is operating off of. Loads are things that use electricity, like light bulbs, washing machines, air conditioners, and of course you can’t forget hot tubs.

So if you’re connecting your solar or your energy storage where those hot tubs are connected, that is called a load-side connection. But if you go on the other side of that main breaker – the main service disconnect – that is called a supply-side connection. Most people do a supply-side connection between the meter and the main breaker. However, you can learn about it in the National Electrical Code – some people even go on the supply side of the meter, which would require separate metering. But typically we think of a supply-side connection as being between the meter and the main breaker.

There’s other things that have happened too with the naming of these things. A supply-side connection – the slang term for that is called a “line side tap,” but it’s not really a tap. It doesn’t follow the tap rules, and that’s not in the National Electrical Code.

There’s another thing that came along in the 2023 National Electrical Code: a renaming for supply-side connections to “source connection to a service.” So they don’t even call it a supply-side connection anymore in the National Electrical Code—except I caught them recently when I was writing my 2026 NEC book. In one of the informational images, they still called it a supply-side connection, but we know what they’re talking about.

Source connection to a service is the new one for supply-side connection. And then instead of a load-side connection, they call it “load side source connection” because we’re connecting a source. Then I caught them on another thing: What if it’s an energy storage system that’s not just a source, but also a load? You gotta charge your batteries, you know? So I’m going to take that back to these NEC people and one thing about the NEC is it’s not something that can really be taken literally. It’s explained differently by different people. You get the top experts in the world and they’ll have different ideas of what something means. And when we’re talking about naming something a source connection to a service versus a supply-side connection, it doesn’t really matter what you call it – it’s just what it is.

So if you want to learn about all of this NEC stuff, I have a bundle of different NEC classes. And we’re going up to the 2026 National Electrical Code right now. 

What it comes down to is this: When you are getting electricity from a utility, there’s something called a main service disconnect where you’ll have overcurrent protection like a fuse or a circuit breaker, and you will have an off switch. If you are on the utility side of that off switch, that’s called a supply-side connection. And if you are on the load side of that switch, that’s called a load-side connection.

Get a load of that.