Load Shed Without Generator

[kwired]

If an electric water heater, they may be able to run with it switched to 120 volts (if their usage pattern permits). I did that to ours when I had to temporarily move it for a month. Never ran out of hot water, even though it took 4 times as long to heat.

Could set up controls that monitor the water heater and isolate the AC unit when WH is heating so they would never run at same time.

But then another question about OP is why is there two ranges, dryers, etc? and are they actually used all at one time.

Seen many cases with a 100 amp main and single range, single dryer, single WH, and AC and no problems holding that 100 amp main, but start adding additional ranges, dryers etc. that do get used often and you might be pushing it.

 

[retirede]

But then another question about OP is why is there two ranges, dryers, etc? and are they actually used all at one time.

I believe the scenario is that a second living quarters was added to the residence for an elderly family member.

 

[gadfly56]

I did a service change many years ago where they only had a 100 amp service that served a farm house and a mechanic’s shop. His elderly mother would holler out the door “Jerell, don’t be welding, I’m starting supper” LOL!

Well, there's your manual load shedding procedure!

 

[hillbilly1]

I did a service change many years ago where they only had a 100 amp service that served a farm house and a mechanic’s shop. His elderly mother would holler out the door “Jerell, don’t be welding, I’m starting supper” LOL!

That was over thirty years ago, I was out there replacing the overhead drop to the shop last year for one of her surviving sons, she is 101, and sharp as a tack! She was getting around very good, but the Covid shot made her dizzy, and fell and broke her hip.

 

[kwired]

I believe the scenario is that a second living quarters was added to the residence for an elderly family member.

OK. I bet in most cases the draw isn't as high as some might think. Can ignore the second range to some extent unless someone is doing an awful lot of cooking or baking, chances are grandma/grandpa eats with the rest of the family quite often as well.

When a water heater or HVAC unit is to be called upon is the main thing that is not so easy for users to control on their own, otherwise they may learn the hard way not to be doing laundry in each unit at same time, in which case you also increase hot water demand from both as well.

 

[ron]

I would come at it from a slightly different angle.
I would challenge you to confirm your thoughts that the service is overloaded with a meter.
I meter my service continuously, and I have a pretty good size home with lots of stuff, 5 people living full time, and it is not that often that my instantaneous draw goes over ~8kW.
A 100A main can handle 24kW for 3 hours (theoretically), which is a crap ton of stuff running at the same time.
You might be worrying about something that is a non-issue, just because they have a lot of circuits connected, they are not all drawing full load at the same time.

 

[kwired]

I would come at it from a slightly different angle.
I would challenge you to confirm your thoughts that the service is overloaded with a meter.
I meter my service continuously, and I have a pretty good size home with lots of stuff, 5 people living full time, and it is not that often that my instantaneous draw goes over ~8kW.
A 100A main can handle 24kW for 3 hours (theoretically), which is a crap ton of stuff running at the same time.
You might be worrying about something that is a non-issue, just because they have a lot of circuits connected, they are not all drawing full load at the same time.

Thank you, sort of what I have been trying to say.

Worst case one may want to find a way to detect peak levels and shed a water heater element or a AC compressor, hopefully only for short periods, to ride through the peak and those two types of loads are the easiest to shed for short time and users may not even know it happened.

 

[Hv&Lv]

I would come at it from a slightly different angle.
I would challenge you to confirm your thoughts that the service is overloaded with a meter.
I meter my service continuously, and I have a pretty good size home with lots of stuff, 5 people living full time, and it is not that often that my instantaneous draw goes over ~8kW.
A 100A main can handle 24kW for 3 hours (theoretically), which is a crap ton of stuff running at the same time.
You might be worrying about something that is a non-issue, just because they have a lot of circuits connected, they are not all drawing full load at the same time.

I agree with this approach as being the best.
My house is 19.5kW peak.
Two 3 ton heat pumps, well, all electric 5 bedroom.
VERY FEW 200 amp services will ever see 200 amps or anywhere close.

 

[winnie]

I think Ron has the best point yet. It is very likely that this service is not actually overloaded (no matter what the Article 220 calculation says). Adding load shedding of any sort might not really be needed.

However the OP has the statement in post 15 " I will say that I can’t remember ever seeing a scenario where someone was routinely popping their main breaker. " If _this_ home is actually popping its main breaker (it is unclear if the OP was saying that this was the case, or saying that they've never seen it happen), then there is an issue to investigate.

If _this_ home is actually popping its main breaker, _and_ a 220 calc says that the service is overloaded, then it is still very likely that the actual home load is less than 100A but there is an issue with the main breaker causing it to trip.

With this in mind, prior to any sort of upgrades or automatic load shedding, I might just install some sort of home energy monitor to alert the residents if they are drawing too much power.

-Jon

 

[gadfly56]

Square D makes remotely operable QO breakers in their Powerlink line. Combine monitoring with an output to remove one or more loads. You'll need to design some manual reset process to prevent relay chatter.

 

[kwired]

I think Ron has the best point yet. It is very likely that this service is not actually overloaded (no matter what the Article 220 calculation says). Adding load shedding of any sort might not really be needed.

However the OP has the statement in post 15 " I will say that I can’t remember ever seeing a scenario where someone was routinely popping their main breaker. " If _this_ home is actually popping its main breaker (it is unclear if the OP was saying that this was the case, or saying that they've never seen it happen), then there is an issue to investigate.

If _this_ home is actually popping its main breaker, _and_ a 220 calc says that the service is overloaded, then it is still very likely that the actual home load is less than 100A but there is an issue with the main breaker causing it to trip.

With this in mind, prior to any sort of upgrades or automatic load shedding, I might just install some sort of home energy monitor to alert the residents if they are drawing too much power.

-Jon

But if this is essentially now two separate dwellings and you have two washers/dryers, two water heaters, two ranges, etc. and both families are on similar schedules with how they utilize the major loads, the risk of drawing high enough to trip a 100 amp main certainly will be higher. Could have same family members but only one kitchen, one laundry area and you are likely much lower with peak demand, and instead will have longer demand periods.