# Line Load Test Points on Commercial Panel?



## dronai (Apr 11, 2011)

That's the bypass test block. You should still get the same readings from any line side terminal.

I just had a similar problem with a 12 Ton AC getting 198V.


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## nolabama (Oct 3, 2007)

Buck it.


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## swimmer (Mar 19, 2011)

nolabama said:


> Buck it.


Boost it?


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## nolabama (Oct 3, 2007)

swimmer said:


> Boost it?


Yes , but buck it sounds better.


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## jmsmith (Sep 10, 2011)

Swimmer-

The switches on the right look like equipment grounding switches. They are usually used to cut-out and ground CTs go a metering circuit. This is done to prevent any arc damage that void result to any metering or relay equipment during testing and/or service.
-Jim


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## guest (Feb 21, 2009)

dronai said:


> _*That's the bypass test block*_. You should still get the same readings from any line side terminal.
> 
> I just had a similar problem with a 12 Ton AC getting 198V.



Ummm..no. 

That is for the current measuring CT's. Yes, you can read the phase voltages there but be warned that opening those links WILL create a very high voltage from the CT's that WILL destroy them.

Don't ask how I know this....:whistling2::whistling2: :laughing:


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## nolabama (Oct 3, 2007)

mxslick said:


> Ummm..no.
> 
> That is for the current measuring CT's. Yes, you can read the phase voltages there but be warned that opening those links WILL create a very high voltage from the CT's that WILL destroy them.
> 
> Don't ask how I know this....:whistling2::whistling2: :laughing:


They say experience is valuable. Lol some lessons are expensive.


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## brian john (Mar 11, 2007)

Potential transformer (or taps) on the left

Current Transformer on the right.

203 depending on time of day is fine.


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## guest (Feb 21, 2009)

nolabama said:


> They say experience is valuable. Lol some lessons are expensive.


Yep and my wallet was a lot lighter and my undies need to hit the trash can...some very scary sounds came from the CT compartment when I played with those puppies. 

POCO guy told me I was lucky I didn't get a severe shock from those levers too.


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## Big John (May 23, 2010)

Ayuh. You may have been on the business end of a couple kV until those CTs burned out. That wouldn't have been fun.

In OPs picture I see 4 PT isolation switches. I'm assuming L-L setup, otherwise what does the fourth switch do?

-John


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