I have 400 amp service from the grid that comes into my house (two 220 breaker panels). If I want to operate a Sol-ark in Limited to Home mode where I grid zero using CT clamps, how would that work in my situation? Would I clamp to just one of the inputs to the 220 panel, and thus be limited to offsetting half of my grid loads?
CT clamps question
- Thread starter chrisw5
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Hedges
I See Electromagnetic Fields!
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One meter, two breakers & panels?
You may be able to put a clamp around one wire which feeds both.
Or a big clamp around two wires, each wire going to one panel.
In either of these cases, the CT has to handle 400A so should be sized correctly. Not sure if excess current would damage it or just be inaccurate. In your case, accuracy only matters near zero amps not at full current.
Or one clamp around wire to one panel, one clamp around wire to other panel. Connect sense lines from the two CT either in series or in parallel (get polarity right so it sums or averages, doesn't show difference.)
With two CT wired together, the absolute measure of current may be incorrectly calculated, but "zero" will still be zero. So long as the two clamps are identical.
Do you have 220V single phase (one line, one neutral) like in U.K. and Europe?
Here in U.S. we have 120/240V split phase so two hot wires, and we would use two current transformers.
You may be able to put a clamp around one wire which feeds both.
Or a big clamp around two wires, each wire going to one panel.
In either of these cases, the CT has to handle 400A so should be sized correctly. Not sure if excess current would damage it or just be inaccurate. In your case, accuracy only matters near zero amps not at full current.
Or one clamp around wire to one panel, one clamp around wire to other panel. Connect sense lines from the two CT either in series or in parallel (get polarity right so it sums or averages, doesn't show difference.)
With two CT wired together, the absolute measure of current may be incorrectly calculated, but "zero" will still be zero. So long as the two clamps are identical.
Do you have 220V single phase (one line, one neutral) like in U.K. and Europe?
Here in U.S. we have 120/240V split phase so two hot wires, and we would use two current transformers.
Yeah, sorry I had a typo. Meant to type 200 amp not 220. I'm in the US. I think I may end up solving the problem by transferring all of my large loads over to panel 1, disconnecting power leads to panel 2 (which has most of my outlets, fridge, and freezers), and using panel 2 as an essential loads panel. That way I can put the CT sensors on panel 1 to offset home loads, but have backup to everything on panel 2 when grid down. Can manage loads on that panel with breakers.
If wires can be run between the two panels you could do something like this: Determine which panel has the greater usage during daylight hours. Install the two CTs at this panel. From the other panel, loop the circuits that constantly have most current draws through the CTs. Use proper phasing and polarity on each circuit. May require larger CTs. Mini splits or inverter ACs would be about the best candidates. Pool pumps also would be good. Computer, video game circuits etc. If you grasp that concept, clamps on the greater usage panel might not be the way to do it. Maybe you should place the clamps on the panel that doesn't supply mini splits, pool pumps etc. Loop them. Conventional heat pumps are a toss up. When they are off, they use next to no electricity, leading to a situation where solar might over generate what is being used. The solar may be wasted. Having mini splits may be a major advantage if two panels are involved.
If I disconnect the leads for panel2, I essentially would now have 200 amp service with mains coming into panel1. Panel2 then becomes a critical load panel, so the CTs on panel1 can offset all loads in the house, correct?
Doing it the way I described, both panels function exactly as they do now. They are both fed exactly the same. All branch circuits function exactly the same. If the panel covers remained screwed on, there would be nothing indicating anything had changed. If the covers were off, branch circuit wires could be seen looping from one panel to the other, through the appropriate CT, and back into their original panel where they would connect to their respective wires that had been connected to the breakers. These branch circuit conductors would just loop into and out of the other panel.
I think I see what you are saying, but I still would need to carve out a critical load panel. Doing it as I has described seems like an easier way for me to make everything work, but maybe I am missing something?
Of course you could install the CT’s at the masthead where the POCO service if fed from......that is assuming that both service panels are fed from one service drop.
I have never seen an approved installation with two panels of the same voltage on one building except where there are two different services (different customers or businesses)
Just curious what jurisdiction you are in.
Of course there is the Class 320 panels...400 amp intermittent duty, 320 amps continuous
That is what is required here in California
I have never seen an approved installation with two panels of the same voltage on one building except where there are two different services (different customers or businesses)
Just curious what jurisdiction you are in.
Of course there is the Class 320 panels...400 amp intermittent duty, 320 amps continuous
That is what is required here in California
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