Clamp Meter used on Main Panel

[hardworker]

To measure the total ampage being drawn by a main panel (Single Phase 240vt) with a clamp meter, do you take the higher of the two measurements of the two hots or add them together?

I am sure I know the answer, but another contractor is disputing me. Please clarify for all of us.

Many thanks in advance for your knowledge.

 

[GoldDigger]

To measure the total ampage being drawn by a main panel (Single Phase 240vt) with a clamp meter, do you take the higher of the two measurements of the two hots or add them together?

I am sure I know the answer, but another contractor is disputing me. Please clarify for all of us.

Many thanks in advance for your knowledge.

If you measure just larger of the two hot currents it will tell you how close to the rating of the service your loads are at that moment. A 200A 120/240 single phase 3-wire service can deliver up to 200A on each of the two hot wires. Any 240V loads will show up equally in both hots.
You cannot choose to take 400A from one hot and zero amps from the other and stay within the 200A rating.

On the other hand, if you are concerned with how much power you are pulling compared to the service rating, you can add the two hot currents, multiply by 120, and get the load in Volt-Amps (VA). How that relates to the wattage consumed depends on the power factor of the loads.

The maximum VA you can take from a 200A 120/240 service will be 48000 VA, or 48kVA. You can derive that either by multiplying 200 times 240 or by adding 200 to 200 and multiplying the sum by 120.