Regarding the consolidation of breakers...Unless your breakers are rated to do so, don't put two hot wires under one screw. Use a short pigtail to the breaker and a wire nut to join 2 circuits to that breaker.
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Service panel upgrade
- Thread starter Eugene k.
- Start date
davewill
Active Member
In your photo it looks like all your two pole breakers are full sized. They can be replaced with tandem breakers as well. They look like this:This was a good suggestion, but it turns out that all my breakers are tandem already
Called the utility again on Monday, left them a voicemail, they promised to call back within 24 hours. Which they didn't, of course.
At this point, I think I'll just go through existing breakers and consolidate them to make room for one more double-pole breaker (there's no way I need 20 15A breakers in the house, I'm not even sure what most of them do), and put in a NEMA14-30 plug as a compromise.
One 240v circuit goes in the middle and one on the outside. They come in various combinations of amerages.
oripaamoni
Member
I live in a condo with a 100A panel. Condo is wired for both Gas and Electric range. Since I have a gas range, there was 40A/240V unused. I had an electrician disconnect the 40A range circuit, and add the 50A breaker for 14-50 charging.
A tandem breaker fits in a single space, but has two handles and two wire connections. They also make tandem 2 pole breakers with inner handles paired, and outer handles paired. Some panels are not rated for tandems, so there are physical keep outs to prevent plugging them in. Busbars are good to 100 Amp or so on a connection, so a tandem 15A or 20A is not an issue, effectively a 30A or 40A breaker.
In this case they likely moved 4 smaller loads from single breakers onto 2 tandem breakers, thus freeing 2 slots for a full sized dual pole.
It is two 20 amp breaker sections in one housing going to two 20A circuits, and taking the space of a single full sized breaker. Not dual feeding one wire.
What was 2 full sized breakers on 2 slots feeding 2 circuits becomes 1 tandem breaker in one slot feeding 2 independent circuits with individual handles.
eprosenx
Active Member
This was a good suggestion, but it turns out that all my breakers are tandem already
Called the utility again on Monday, left them a voicemail, they promised to call back within 24 hours. Which they didn't, of course.
At this point, I think I'll just go through existing breakers and consolidate them to make room for one more double-pole breaker (there's no way I need 20 15A breakers in the house, I'm not even sure what most of them do), and put in a NEMA14-30 plug as a compromise.
Yeah, so I might recommend getting a "Sense" unit (I have one). It has current CT's that go on your main feeds plus on your solar backfeed. It can show you how much power you are actually drawing. While this has nothing to do with actual NEC load calculations, it might give you a "practical" idea of how much power you are really using at peak. Also, looking at your power bill might be helpful to determine if you are actually a high user or not (it won't tell you about peaks though). If your power company has high precision monitoring you may be able to login to the web site and get some idea of peak draw (but again, probably not detailed enough to be really useful).
Note that you would really need to watch power draw over a full year in order to understand at what time of year seasonally you hit peak (I am guessing AC though - unless you have electric heat?). Oh also, one option might be to see about converting to a gas dryer and or water heater in case any of those are electric right now... Might be cheaper than upgrading the electrical service. Or get a "dryer buddy" to interlock so you can't charge the car and run the dryer at the same time. This should allow you to avoid worrying about NEC load calculations (though now that I think of it, I wonder if the dryer is counted as non-continuous and a car is continuous so perhaps that would change the calculations).
I have never done a service upgrade in residential, however, my understanding is that for existing electrical services in my area, everything upstream of the point of demarcation is the responsibility of the power company if it fails or is not of sufficient capacity. In my case I think this demarcation is my meter pan, but on new properties the power company does the handoff in a pedestal in the front yard.
Regardless, I have seen the power company come out and upsize transformers on their own because the usage patterns they are seeing via their remote metering indicate an overloaded situation.
So while the work to do the new panel and such on your side might be expensive, the actual utility side of the work may not be too bad.
And to second what others have said, typically the power companies are pretty good at trying to keep users "in service". As stated, often they will kill power in the AM and then come back and re-enable it late in the day. Also, if you can pre-install a new panel (often on the side of the house outside) and run new conduit back to the transformer, they may be able to energize the new one before de-energizing the old one (or do it at the same time) so you are out of power for a very limited period of time. Often times you will end up leaving your existing panel in place untouched and just making it a subpanel off a new "service entrance". A very common setup for 320/400a service is to put an external panel on the side of the house with the new 320a meter plus two service disconnect switches. Commonly one of them will have a few breaker positions plus bare terminals off the bottom of the bus and the other will just be a bare terminal by itself. So you could hook the existing panel off that dedicated set of bare terminals and you could even just install the car charger breaker direct in those open breaker positions and it would have a full 200a to itself.
Can you include a picture of your panel that is detailed enough to see all the breaker handles? Plus one of the "service schedule" which lists all the uses of the various circuits? Plus one of the sticker on the door that has all the gory details about the panel (part #'s for breakers and such to go inside it). Just wanted to make sure there is no chance to squeeze a couple more in there! You are right that you could potentially collapse a couple 15a circuits (though most breakers are not listed for having two wires under one terminal, so you might have to wire nut pigtail them).
Also, the HPWC is actually in a lot of ways more flexible than a NEMA 14-50. You can wire the HPWC with whatever size circuit you want (say 60a so you can do a full 48a for a Model 3 long range) and then you can control what it *actually* draws max via a rotary dial inside the HPWC. So maybe wire it for 60a, but then if your load calcs don't allow for it, then set it down to whatever setting your house can support. I believe that setting it down lower should effectively change its nameplate rating and be kosher with the NEC. Having to remember to "dial it down" in the car itself I am certain would not meet NEC requirements.
P.S. The AC units (and anything with a motor) will have huge breakers in order to avoid blowing them upon motor startup. They have separate ways to do actual "overcurrent" protection. The load calcs are based on the actual motor rated draw vs. what it is breakered at.
Edit: I just realized there was a second page of the thread I had not read before posting this and I also found the picture of the panel in question. That panel is quite full! Those combo meter and disconnect units are pretty tight. I am not sure how well a Sense would fit in there or if there is anywhere easy to get CT's around the mains. I don't recognize that model of breakers either. It does not look like they are true "tandem" breakers (just really narrow individual breakers). Are they perhaps Square D? If you are lucky, an electrician may be able to figure out how to squeeze another 240v breaker in there somehow and figure out some load setting on a HPWC (or otherwise use a smaller receptacle like a 14-30) that would let you stay below the calculated load limit.
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