Somewhere on your ComEd bill there is a phrase like Small Load or Medium Load. It is not marketing language and it is not a description of your business. It is the delivery class ComEd has sorted your account into, and it decides which filed rate gets applied to your kilowatts.
Owners find this line and immediately ask the same question: if the class is set by how much power I draw, can I hold my demand under the threshold and pay the cheaper class? The answer is worth knowing before you spend anything to engineer it, and it is not the answer most people expect.
The classes, and what actually separates them
ComEd's Retail Delivery Service sorts nonresidential accounts by demand. The lowest tier, Watt-Hour, is billed on energy, in dollars per kilowatt hour. Every tier above it is billed on demand, in dollars per kilowatt of your highest qualifying half hour. Small Load covers accounts under 100 kW. Medium Load runs from 100 to 400 kW. Above that sit Large Load, Very Large Load and Extra Large Load.
The first boundary is the only one that changes the shape of the bill. Moving off Watt-Hour into a demand-billed class means a demand charge appears where there was none, set by a single half hour rather than by a month of consumption. That is a structural change and it is worth understanding the moment it happens.
Every boundary above the first is a rate change, not a structural one. You are billed the same way. The number in front of your kilowatts is different.
The threshold is not a cliff, and this is the part that matters
Here is the thing the "stay under 100 kW" instinct gets wrong. Read the filed base rates across the classes on the Distribution Facilities Charge page and you will see the per kilowatt base fall as the class rises. Small Load and Medium Load sit within a few percent of each other, and the larger classes are lower still.
So crossing 100 kW does not move you onto a punitive rate. It moves you onto a slightly cheaper one, applied to considerably more kilowatts.
That reverses the usual framing. The money in a ComEd demand charge is in the kilowatts, not in the class. A site that shaves from 105 kW to 99 kW saves the value of six kilowatts, and it does not matter very much which side of the line those six were on. A site that shaves from 105 kW to 80 kW saves the value of twenty five, and the class question never enters into it.
An engineering project justified by "getting under the threshold" is being justified by the smaller of the two effects.
What your bill and your rate class actually tell you
Two things are worth reading off the bill you already have, and neither requires any data you do not possess.
The class name. It tells you which filed rate applies and, more usefully, whether you are demand-billed at all. If you are on Watt-Hour, no amount of peak management changes your bill, because nothing on it is priced per kilowatt.
The billed kilowatts. This is the number the class rate multiplies. It is also the number that answers the only question that matters here: how far above the threshold are you, and how far above your own second-highest half hour is your peak. The second gap is the one that sizes what peak management can actually recover, and it is invisible on the bill.
What we can say with confidence, and what we cannot
We have reconciled real ComEd bills to the cent in the Small Load and Medium Load classes. For Large, Very Large and Extra Large we have the filed rates from the informational sheets but no reconciled bill yet, and we mark that difference rather than smoothing it over. If your account sits in one of those classes and you want the rate confirmed against your own bill rather than against a filing, that is a reconciliation we have not done and would want to.
What is not class-dependent at all: the on-peak window that decides which of your intervals is even eligible to set the charge, and whether your peak is a single reducible event or the ordinary shape of your operation. Those are read from the interval data behind the bill, and they decide far more of the outcome than the class name does.
How does ComEd decide which delivery class my business is in?
By your demand history on the account. The classes are demand bands under Retail Delivery Service, with Watt-Hour at the bottom, then Small Load under 100 kW, Medium Load from 100 to 400 kW, and progressively larger classes above that.
Is it cheaper to stay in a lower ComEd delivery class?
Not in the way people assume. The filed per kilowatt base rate generally falls as the class rises, so crossing a threshold moves you to a slightly lower rate applied to more kilowatts. The saving from reducing demand comes from the kilowatts you removed, not from the class you avoided.
What is the difference between Watt-Hour and Small Load?
Watt-Hour is billed on energy, in dollars per kilowatt hour. Small Load is billed on demand, in dollars per kilowatt of your highest qualifying half hour. That is a change in how the bill is constructed, not just in the rate.
Where do I find my delivery class?
It is named on the delivery portion of the ComEd bill, usually alongside the rate description. If your bill shows a charge stated in dollars per kW, you are in a demand-billed class.