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Yesterday I took a picture but forgot to took the info plate for amperage rating on it. enter image description here

My main question: Is there a way to calculate the total amperage that load center currently has?

Extra question: Can you also calculate the amperage rating by looking at it also?

Thanks in advance.

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In a case like this the easiest way to gauge service size is simply looking at the main breaker. Keep in mind, every part of the service; riser, meter pan, entrance cable, etc...must be sized and rated for the service size.

In this case it looks like a 200A service. What you have there is a 200A, 20/40 main breaker panel. 20 full size spaces that can all accept twin, or tandem, breakers.

Not sure what you mean by what amperage the service "has". You can tell the service size like I explained, and you can tell what the load is at one pin pint in time by using a clamp-on amp meter.

You can tell what the calculated load is by doing a load calculation on your home, although this is not an accurate number of actual draw. Here is one example: http://www.nojolt.com/load_calculations.shtml You can do a web search for lots of info on load calculations.

Bear in mind, adding up the breakers in the panel is a completely meaningless number and will NOT give any kind of assessment of load. It is not uncommon to see 600-800 amps worth of breakers in a 200A panel.

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  • How can you tell that it's 200 amp service? – Tester101 Nov 26 '15 at 14:36
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    @Tester101, Experience. From the size/shape of the main breaker and the size of the entrance conductors. Seen a million of them. – Speedy Petey Nov 26 '15 at 14:51
  • I agree it looks like 200 + to speedy good answer on total load – Ed Beal Nov 26 '15 at 15:57
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    This is nothing new. See link – Kris Nov 26 '15 at 17:59
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    Not really. You found a couple of old threads on Mike Holt, which I only frequent once in a while so no, I didn't see them. That does not make it old news or a popular issue. I have also moderated an electrical forum since 2007 and from my recollection this has never come up. No, in all my years this has never come up, least of all from an inspector. And I have done hundreds of 200A services. ........... I will also say I 100% disagree with the interpretation that 338.10 completely negates T310.15(B)(7). The notion is absurd. – Speedy Petey Nov 26 '15 at 18:05

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