Electrical Service Overload Alerts

#1

I would like to be able to tell the Sense unit how many amps of power my electrical service is capable of from the utility (100, 125, 150, 200a, etc…) and then have it alert me if I approach or exceed it.

Where I see this being useful is that right now a LOT of people are getting EV’s and adding charging to existing electrical panels. The concerning ones are the 100a, or 125a services (or even some 150 and 200a services). EV’s can draw a ton of power, but full service panel replacement/upgrades are quite expensive.

So any kind of monitoring the Sense can provide would be useful!

This could also be interesting to help understand bus loading on a panel with solar backfeed. It would be interesting to see if you are utilizing more amps in aggregate than your panel is rated for (since code allows you to overload it by 20% when backfeeding solar into the load side of an existing panel).

Additionally, for EV charging, being able to run a report on power consumption peaks for the last year would be interesting to prove how much headroom on a service was available in order to allow installation of EV charging without needing an upgraded panel. Showing actual usage numbers is an alternative to using “calculated” load profiles which are generally far off.

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#2

How much do EVs usually use? I was hoping to afford one in a few years. I have a 200 amp service at 220. I ran100 amps to my hanger that has a very small load <3 amps for door is max. Lights are also less. I have a 9.5 Kw solar array. Since 5/3/19, my max draw has been <8Kw, less than 40 amps I am guessing, with HVAC and water heater running. The water heater is a 5Kw user and HVAC is about 1.2 Kw at 40%. I have a smart HVAC system with variable fans and compressor run by a Trane 1050 Tsat

#3

Wow, a Tesla charger for 240V typical residence unit is 80 amps. The 480V supercharger is 300 amps. Few homes have 480V available. The equipment cost is probably very high. Found this at https://www.pluglesspower.com/learn/tesla-model-s-charging-home-public-autonomously/

#4

One great thing about Teslas is the wide range of charging options you have. They can accept anything from 12a @120v (15a circuit) through 80a @240v (100a circuit). Though each model of Tesla has an onboard charger which is typically not able to make use of the full 80a. I wrote up a primer on this topic here that should give you some background:

https://www.article625.com/2019/05/01/how-should-i-charge-my-tesla/

Most Teslas now come with a 48a onboard charger so I probably would recommend you use a 60a circuit to feed a hardwired Tesla “Wall Connector” to charge the car.

Note that I look forward to the day that someone comes out with an EVSE (electric car charging connector) that has functionality to monitor the total current load on your electrical service. You could have it constantly vary the current allowed to the car to keep the overall service load under the service capacity.

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#5

I have a 2014 BMW i3 and a level 2 charger installed in my garage and it only draws 32A when charging BUT having a feature that tells us how much amperage our current load is would be a nice feature.

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#6

There is quite a bit of hardware out there to do this. Commercially there are several integrator company’s that do this.The cost is relatively high for a homeowner with the only reason being nice to have. I use these people for my commercial endeavors. They are not alone, but I have known them for years. https://entronix.io/

#7

Overload alert is easy to do with the “goals” feature. Set a goal to keep your usage below a certain wattage at all times. As long as your power factor is close to 1, this will do what you’re asking for.

With 100A service and the ability to pull about 200A if I try, this was one of the first goals I set up when the feature was released.

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#8

That’s what the panel main breaker is for. If you exceed the panel rating, if the breaker has been sized correctly, it will disconnect.

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#9

@harvs is correct.
It’s not unusual for a panel to have individual breakers that add up to 400 or even 500 amps in a 200 amp panel. The likelihood of enough being on to throw the main would be highly unusual and I have yet to see a main breaker tripped.

#10

Yes, this is the main breaker’s job, but I’d rather get a heads-up before the whole house goes dark so that I can do some manual load shedding.

Fortunately this isn’t something that’s ever happened to me.

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#11

So I want to be able to set an alert for some arbitrary level below where we think the main breaker will likely trip (since they are thermal devices they are not really all that accurate).

Knowing when you are close might allow you to do something before the main trips (the main is say rated for 200a, but it also could blow at a lower level than that if you have “continuous loads” like EV charging heating it up). This is why you effectively are only allowed to use 80% of a circuit or main breakers capacity when you have “continuous load” devices like EV’s.

So I would want to set my alert level to say 160 amps on my 200a service.

You never want to trust a breaker to function as they do indeed fail fairly regularly or don’t trip right where they are supposed to.

Also, some panels have no main breaker at all. Split bus panels with up to six individual main disconnects (for large load items like ovens, heating, AC, etc…). You could overload the service without any main breaker to protect you. (though that is what load calculations are for)

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#12

I agree @eric2. I’ve been pushing for this elsewhere on the forum and think it’s an inevitable feature. I’m not sure what the rationale for not doing it is?

A per-Sense (vs per-Device) max watt alert.

I have a 100A panel and l could live on the edge of overload if I didn’t carefully craft the loads. If my remote main trips (which has happened a few times) and it’s overnight I have no way of resetting it until the following day (my meter is in a commercial space). That’s only happened once in 25 years but you can imagine how frustrating that is.

Mains do trip especially on big loaded panels. My panel only has 12 breakers but I’m all electric heat & hot water so it’s not always the case that a panel breaker overload will prevent the main from tripping.

I’ve actually used a Sense (temporarily) in a commercial setting (a restaurant) to troubleshoot overload issues, as outlined here.

#13

Unless I am missing something, this already exists. You can set an alert for any usage. I have mine set at 10 kW. My panel nominally supports 220 V x 200 A = 44 kW, but we have yet to exceed 10 kW at any one time.

(It is in W and not A, but that should be sufficient, since reactive power will never be a large fraction)

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#14

Oh my, no you aren’t missing something, you are so right on that.
I completely let the Goals feature slip … it was introduced after I had burrowed through everything.

OK, done. But here’s something odd: in doing that setting, “Peak over past week” is definitely wrong. My peak is more like 7kW. Anybody see similar discrepancy?

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#15

@ixu Thanks for this thread. I have created a similar goal based off of this conversation.

In regards to you “Peak over last week” question, I have the same discrepancy. It states 838W, but I have peaked over 7,000kW.

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#16

Same here, peak over last week is 10 times too small. Maybe there is some math error and we just have to multiply it by 10?

#17

In the example above mine is somewhere between /4 & /5 so it seems more complicated.
I just initiated a support request on this … let’s see what they have to say.

#18

@pswired also mentioned Goals above :slight_smile:

Let me look into your question about peak.

Also, since this seems to be answered, I’m moving to Technical Questions. @eric2, let me know if you disagree with that.

#19

@ixu @rob.koekkoek @jlj.pers Seems like a bug! Please submit tickets to the Support team (support@sense.com) and we’ll get it fixed.

#20

Thanks! Just submitted a ticket to support on this.