Sean S
Titanium
- Joined
- Dec 20, 2000
- Location
- Coos Bay, OR
Hi all,
In my ongoing mission to get accurate Kwh readings from my 3 phase drop, I have purchased a Kwh meter.
The meter uses 3 current transformers and a line to neutral (and also a line to the legs I think.
All is good except I have an oddly wired drop and mains cabinet.
The service is 3ph 240 (Delta I've been told) with a hot leg.
The drop is 4 wire.
Now the weird part...
The mains cabinet has 2 identical weatherheads at the roof.
Each drop line splits into 2 lines (is tapped) at the end of the drop just before the weatherhead.
Basically each line becomes two parallel lines.
Now I would think this is because of an amperage issue with the wires that go through the weatherhead (doubling them up), but the actual lines going through the weatherhead are just about (if not) the same size as the drop lines.
I can only imagine that at some point the drop was of a wire gauge that wouldn't fit through the weatherhead and so two weatherheads (and two sets of wire) were used instead to get the amount of copper through there for the required service and since then the drops were replaced with a smaller gauge.
I'm guessing here since...as stated...it looks like the actual drops might fit through the weatherhead openings.
The end result however is that I end up with two sets of 4 lines inside the mains cabinet...which are simply paralleled back to the 3 bars and one to the ground (neutral?) bar.
This all works fine but here's my problem...
I want to install a Kwh meter that uses 3 CT's around the incoming wires (legs), but I actually have 6 if I only count the "hot" wires.
Obviously the reading would be incorrect if I only put the CT's around half of the paralleled wires.
The ID of the CT's is 2" which isn't enough to get 1 CT around 2 wires nor enough to get around the bar itself (if this would be OK or not....dunno?).
I actually have 6 of these CT's...just for reference.
So I'd like some advice on these options I've come up with....
1. Have the electric company come and re-wire the weatherheads for 4 wires instead of 8 (expensive).
2. Find a way to get 3 CT's around the bars (might be possible but I'm not sure bars have the same inductive qualities as wire...though it would seem they would).
3. Use 6 CT's on the 6 wires.... which I don't know if it can or should be done, nor if I would wire the 2/4 CT wires in series or parallel to get the correct amperage to the meter.
The CT's are 300/5a (60:1) if that matters.
Pictures coming...
Advice here would be greatly appreciated!
Many Thanks
Sean
In my ongoing mission to get accurate Kwh readings from my 3 phase drop, I have purchased a Kwh meter.
The meter uses 3 current transformers and a line to neutral (and also a line to the legs I think.
All is good except I have an oddly wired drop and mains cabinet.
The service is 3ph 240 (Delta I've been told) with a hot leg.
The drop is 4 wire.
Now the weird part...
The mains cabinet has 2 identical weatherheads at the roof.
Each drop line splits into 2 lines (is tapped) at the end of the drop just before the weatherhead.
Basically each line becomes two parallel lines.
Now I would think this is because of an amperage issue with the wires that go through the weatherhead (doubling them up), but the actual lines going through the weatherhead are just about (if not) the same size as the drop lines.
I can only imagine that at some point the drop was of a wire gauge that wouldn't fit through the weatherhead and so two weatherheads (and two sets of wire) were used instead to get the amount of copper through there for the required service and since then the drops were replaced with a smaller gauge.
I'm guessing here since...as stated...it looks like the actual drops might fit through the weatherhead openings.
The end result however is that I end up with two sets of 4 lines inside the mains cabinet...which are simply paralleled back to the 3 bars and one to the ground (neutral?) bar.
This all works fine but here's my problem...
I want to install a Kwh meter that uses 3 CT's around the incoming wires (legs), but I actually have 6 if I only count the "hot" wires.
Obviously the reading would be incorrect if I only put the CT's around half of the paralleled wires.
The ID of the CT's is 2" which isn't enough to get 1 CT around 2 wires nor enough to get around the bar itself (if this would be OK or not....dunno?).
I actually have 6 of these CT's...just for reference.
So I'd like some advice on these options I've come up with....
1. Have the electric company come and re-wire the weatherheads for 4 wires instead of 8 (expensive).
2. Find a way to get 3 CT's around the bars (might be possible but I'm not sure bars have the same inductive qualities as wire...though it would seem they would).
3. Use 6 CT's on the 6 wires.... which I don't know if it can or should be done, nor if I would wire the 2/4 CT wires in series or parallel to get the correct amperage to the meter.
The CT's are 300/5a (60:1) if that matters.
Pictures coming...
Advice here would be greatly appreciated!
Many Thanks
Sean