Current transformers in a panelboard

[templdl]

iwire, nice work.

I guess that answers my question as to if its allowed by code to put CTs in a panelboard. Last question, does the secondary of the CT need to be grounded? In this case, it wasn't.

What were the CTs connected to and terminated? Was there a common connection for one side of the CTs and a separate connection for each of the remaining 2 wires?
It may be that there is a grounding connection at the common connection between the CTs. If not I would review the instructons for proper installation. A the point of common connection is usualy the point where the grounding connection is made from what I have seen.

 

[fmtjfw]

250.170 Instrument Transformer Circuits. Secondary
circuits of current and potential instrument transformers
shall be grounded where the primary windings are connected
to circuits of 300 volts or more to ground and, where
on switchboards, shall be grounded irrespective of voltage.

Exception No. 1: Circuits where the primary windings are
connected to circuits of less than 1000 volts with no live
parts or wiring exposed or accessible to other than qualified
persons.

Exception No. 2: Current transformer secondaries connected
in a three-phase delta configuration shall not be
required to be grounded.

 

[stevephillips]

What were the CTs connected to and terminated? Was there a common connection for one side of the CTs and a separate connection for each of the remaining 2 wires?
It may be that there is a grounding connection at the common connection between the CTs. If not I would review the instructons for proper installation. A the point of common connection is usualy the point where the grounding connection is made from what I have seen.

Each CT went to an ammeter and a power analyzer. No grounds on either. I already left the job so this is for my own reference.

 

[stevephillips]

120729-1340 EDT

steve:

Are there two voltmeters or just one. If a single voltmeter, then does it measure leg to leg or just one leg to neutral?

Are there two ammeters or just one?

Is there other circuitry to measure power? Because power at a home is not simply V*A. Any recording equipment?

Are the meters RMS reading?

By any chance did this customer also install a whole house power factor correction capacitor?

Can this customer actually reduce his electric bill as a result of having installed this instrumentation? How often does he run to the main panel to read the meters? What did these meters, and associated equipment cost?

.

3 volt meters, 2 ammeters and one PF indicator along with some kWHr meter that keeps track of everything. I got the feeling that he is a data nerd. I didn't get a picture of the entire panel, just the CTs. Sure did use lots of tape.

 

[templdl]

Each CT went to an ammeter and a power analyzer. No grounds on either. I already left the job so this is for my own reference.

Without having a schematic to review it would be hard thing to assess his design. I don't know if grounding would be any big deal of not in this example but the only concern that I have with CTs is when they are open circuited while the system is under power where the voltage across the open part of the circuit will go through the roof. Should some unsuspecting know it all mess around with it not knowing what their doing that would be an issue.

 

[gar]

120731-1748 EDT

iwire:

What is the name of the company that made the monitor system that you installed? And the part numbers of the current sensor, and remainder of the system?

.

 

[iwire]

Gar,

The equipment is from http://www.outsmartinc.com/

 

[ritelec]

I think you are correct, Judging from the tape job, they did pull the meter, it would be really hard to tape like that live.

And the bug splice.


iwire nice install.

I know anything flies when engineers design things, but I'm curious to the wire about the ct's.......

Is it rated (or have to be) for the voltage (600v) as the other line conductors in the panel?