Author Topic: spyder CT sizing  (Read 1646 times)

TVRfan

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spyder CT sizing
« on: October 16, 2016, 01:18:56 PM »
Hello. I just installed my Pro with 2 spyders. I have a question that I couldn't find a precise answer to in previous posts. I am not an electrician, but have a general understanding of what is happening in my panel.

I have one 40 amp/240 circuit to my range that I'd like to monitor. I placed one 20amp spyder CT on each 120v feed wire. Since they are 20 amp CTs on a 40 amp circuit, am I going to burn my house down?, Or will I just not get an accurate rating if the circuit is drawing more than 20 amps?

A little reassurance is appreciated.

Thanks in advance,
Elden


Support7

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Re: spyder CT sizing
« Reply #1 on: October 17, 2016, 08:44:56 AM »
The main thing to remember regarding CT size is not to exceed the listed amperage but if I am understanding you correctly then you are trying to monitor a double pole 40A breaker so each leg of that would be 20A (in a single phase service, 3 phase service can reach the listed amperage per phase) so a 20A CT would be fine as long as you have 1 leg of the double poll breaker going through each CT. The most that would happen is you would get inconsistent readings. There's nothing to overheat as it is just taking measurements with the CT and not actually pushing or pulling power.

Have a wonderful day!

TED Support
www.theenergydetective.com

TVRfan

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Re: spyder CT sizing
« Reply #2 on: October 17, 2016, 07:21:08 PM »
Perfect. Thank you. I'm up and running.