I’m currently taking the Residential Electrical Inspection course and it says “the inspector shall describe the main service disconnect’s amperage rating.” But I’m not clear on how to do so. Can anyone explain?
Read the ampere rating of the main service disconnect circuit breaker. 200A is most common in my ventures followed by 150A.
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Well, the amperage is either the breaker rating, or the rating of the service feeders, whichever is less.
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Yeah, the lesser of service conductors rating, breaker rating or cabinet rating is the amperage rating.
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Read the question again. He is asking about the Disconnect rating, NOT the Service rating!
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So you can read the question, I’m sure it made your day to correct someone. Too bad you couldn’t answer the OPs question.
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The literal answer is the number stamped on the service disconnect. Typically a breaker. It could also be a fused switch-box. Neither is typically important for the home inspection and I believe the question, like so many in Inachi courses, is miss-worded. What you want to know is the service amperage and it is as indicated above by Daniel and Larry.
What if there is more than one service disconnect?
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Thus the reason for the inspector to describe the method of Disconnect in the inspection report!
Safety!
The “Main Service Disconnect” typically refers to the breaker at the service panel (outside) that supplies the main distribution panel (inside). Not all service panels will have a single disconnect as in DF’s example. In that case it will be the highest rated breaker in the service panel and is usually marked as Main and between 80-100 amps. Depending on the age of the home the main service disconnect may be located in the distribution panel and should not exceed the panel rating.
There usually is more than one. What’s the Main?
Except the OPs question didn’t ask to describe the “method;” it asked to describe the “amperage.” Two entirely different things.
You just make it up as you go along, don’t you!
I thought about that too, but the coursework also says we are required to list the service amperage.
So I assumed he was asking the wrong question. I mean, if he doesnt even know how to read the numbers on the main disconnect, then he has a LOONNGG way to go to becoming a licensed inspector…
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I understand your statement, BUT… what is Rule #1… NEVER ASSUME!
What if he asked exactly what he intended to ask?
It doesn’t matter what you and I may think, it’s what the OP asked that I reply to.
If you question the validity of something, ask for clarification.
A typical residential service has only one service disconnect. However there can be more than one like in a split-buss panel or for a 400 amp service with 2-200 amp panels fed directly from the meter or CT cabinet.
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Morning, Andrew. Welcome to the InterNACHI forum.
Lets start by breaking down your question. How to rate the main service disconnect by ampacity.
What is a main service disconnect?
The main service disconnect is a means for which one disconnects the building from the power utility supply.
Typically the disconnect is in the form of a Breaker or Lever, dependant on the piece of equipment used. Breaker or Fuse.
The ampacity will be labeled on the Breaker handle or Fuse Box Enclosure called a Safety Switch Enclosure. The numbers represent the maximum ampacity for that disconnect device.
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Here’s how I describe the service type and disconnect amperage in my reports, these are shots taken out of an actual report.
As they say, a picture is worth a thousand words. 
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Thanks, lots of helpful answers.
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Jonass follows rules! Now that is a hoot!
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