Adding an electric car charger to a 100 amp panel?

[Newsletter Writer]

Hello Folks:

I'm not an electrician. I have been asked to write an article for our condominium corporation newsletter to advise homeowners that they might need to upgrade their home's electrical panel from 100 amps to 200 amps if they purchase an electric car and want to install any form of charger for the car other than something that plugs into a standard 110 volt 15 amp outlet.

It's not my intention to tell homeowners how such an upgrade is done. The purpose of the article is to advise homeowners to investigate, with an electrician of their choice, exactly how much work will need to be done and to determine with their electrician what this will cost before they purchase an electric car.

Our community consists of 70 townhouses in Metro Toronto that were built in 1980. The units have between 1 and 3 bedrooms and vary between 1,500 and 1,900 square feet, including the finished basements. When the units were built, none were equipped with air conditioners, and all were fitted with 100 amp service panels. Since then, every single owner has added an air conditioner.

When I look at my service panel, which is typical of all the other units in our community, I see the following:

1. All the breaker spaces are occupied, there are no empty spaces left.
2. There is a 20 amp double breaker for the air conditioner, and two 40 amp double breakers, one for the dryer and one for the stove.
3. There are three 15 amp double breakers that service kitchen outlets.
4. The remaining twelve 15 amp breakers service lighting, the fridge, the smoke detector, and other outlets.

In 2017, Toronto Hydro upgraded all the underground wiring in our community, from the 27,000 volt transformers all the way to the individual electrical meters at the front of each home. Presumably when the new wires were run from the distribution transformers to each home's meter box, Toronto Hydro ensured that these wires could cope with more than 100 amp service, but this is a presumption, not a known fact.

Our Property Manager believes that if a homeowner wants to install a charger for an electric car (other than a 110 volt, 15 amp plug-in charger) the homeowner will need to have their electrician do the following:

1. Upgrade the size of the electrical panel from 100 amps to the next largest commonly used size (presumably 200 amps).
2. Install, at homeowner's expense, a new set of wires in the conduit leading from the electrical meter to the power panel.
3. Possibly install a new base plate for the electrical meter (this depends on whether or not the meter base plates were upgraded in 2017).

Would you folks please let me know if you think the above work will be necessary? Personally, I think our Property Manager is correct and it will be necessary to upgrade the service panel, but I don't want to put out a newsletter saying "Hey, you might be looking at some big expenses if you want to install a car charger" if that is not correct.

Thank you very much for any advice and criticism you can provide, and thank you also if you can provide me with any web links you think I should include in the newsletter article to better inform homeowners about what they need to know.

 

[Jraef]

I’m allowing this because you, although not an Electrician, are not asking for “How to...” advice and work will be done by quaffed electricians.

As to the presumption of the work necessary, I would put the term “probably” in the preamble. To point 1, the need for an upgraded panel is based on actual connected load, not the number and sizes of the breakers. There are prescribed load assessment procedures that electricians must follow, it’s not something that can be done via guessing. Items 2 and 3 however would be dependent on the outcome of the real load assessment, but if they do have to increase the service, both would have to be done, no ambiguity there.

Collectively, there may also be impacts for the entire complex based on the answer (no assumptions) on what was changed in the conductor sizes and transformer sizes involved. But electricians cannot assess that, only the utility can. They have different rules.

 

[suemarkp]

Typical panel sizes are 100, 125, and 200 amps. It is possible people have 125A panels with 100A main breakers. It may be possible to just change the main breaker and not have to upgrade the entire panel (unless they don't have any extra panel slots). But the electrical feeder wires feeding the panel would need to be upgraded from 100 to 125 amps wires. If those are in conduit, and they didn't over size it, the conduit may have to get replaced which could be expensive if any are buried under concrete. Even these minimal changes are not inexpensive.

There are 240V car chargers that can be set for different charge rates. A 240V 24A car charger is about the same load as an electric clothes dryer (30A circuit). But 32A and 40A charge rates are common for Tesla's (these would require a 40A or 50A double pole breaker). The smaller 24A charger may work in the existing panels, but a load calculation would have to be performed to really know. Interlock or time based load shed/switching devices could be installed that disallow you from running the clothes dryer when charging the car. This could possibly work without a panel change at all. As Jraef said, you need to assess the specific items for each unit to know what its existing load is, what equipment you have, and how much it can be expanded or load shed. If all units are the same, that helps, but if some have added things besides air conditioners that messes up the calculations for them.

But Jraef also alluded to another issue. If a substantial number of units begin to install car chargers, the load of the whole condo complex could increase substantially (a clothes dryer may run for an hour, a car charger could go for 6+ hours or more so the odds of overlapping loads gets higher). The transformers feeding the complex or groups of units may be too small and maybe the wires too. This is going to be a problem for many apartments and condos to address and there may be resentment from people who don't want an electric car being assessed charges for site electrical upgrades to accommodate those that do. I've often brought up that point for places like California that want to outlaw internal combustion cars and go all electric. What are people in apartments and condos supposed to do to charge their car? Massive electrical infrastructure upgrades need to occur to make this a reality and many people don't like to pay for that. Newly built units with these provisions will have an advantage.

 

[wwhitney]

FWIW, there are currently non-commercial (e.g. DIY) EVSEs with power control. Meaning they monitor the load on a panel's feeders (with CTs) and adjust the allowable EV charge rate to keep the total load below some setting. So if such a thing becomes commercially available, it could easily be a less expensive option to upgrading a feeder.

Cheers, Wayne

 

[augie47]

Playing with generic numbers, a 1900 sq ft dwelling with electric clothes dryer, range and air conditioning would not allow the addition of a charger.
One commonplace method here would be to install a new panel at the meter location re-supplying the existing panel and adding a circuit for the charger.
The particular details would need to be worked out by an electrician in consultation with an inspection agency.
I definitely agree if this is going to be a widespread install, discussionw with the local utility is in order.

 

[LarryFine]

Without seeing the building layouts, it may or may not make sense to run EV circuits from the existing panels.

 

[Newsletter Writer]

Thanks very much to all of you for the wise and carefully thought out responses.

@Jraef - thank you for permitting my question to stay up.

@suemarkp - Good catch - I looked at the panel in my home, it is a 125 amp panel with a 100 amp main breaker. This means that the panels in all the other homes will also be the same. I think, though, that the stumbling block for everyone will be that their panels are probably already filled up with breakers because homeowners have added air conditioners (and possibly additional electrical outlets) in the past 40 years

The plastic underground conduit running from the meter box at the front of each home to the electrical panel of each home (a distance of about 30 feet, including the two vertical portions) has an OD of 1.67 inches (42 mm). Do you think this provides sufficient ID to allow new wires to be pulled to support an upgrade to 200 amp service, if the homeowner elects to upgrade to a 200 amp panel?

Concerning the overall load for the whole complex, when Toronto Hydro did our transformer & underground wiring upgrade in 2017, they installed new buried conduits 900 mm below ground encased in concrete running from the new local transformers (27,000 volt) all the way to the meter boxes at the front of each home, and ran new wires to the meter boxes. They also replaced all the meter boxes, which suggests to me that the new meter boxes might be designed for a higher capacity than the originals. Hence my concern is not so much with whether the neighborhood supply can cope with the load - my concern is that homeowners will need to get some serious electrical work done within their home if they want to install a Level 2 charger.

Many, many thanks to all of you for taking the time to respond. This will help me to write an accurate and credible "head's up" to everyone. I'll come back and post the text of the article here on this thread once I have sent it out to everyone.

Michael, Toronto.

 

[Little Bill]

Thanks very much to all of you for the wise and carefully thought out responses.

@Jraef - thank you for permitting my question to stay up.

@suemarkp - Good catch - I looked at the panel in my home, it is a 125 amp panel with a 100 amp main breaker. This means that the panels in all the other homes will also be the same. I think, though, that the stumbling block for everyone will be that their panels are probably already filled up with breakers because homeowners have added air conditioners (and possibly additional electrical outlets) in the past 40 years

The plastic underground conduit running from the meter box at the front of each home to the electrical panel of each home (a distance of about 30 feet, including the two vertical portions) has an OD of 1.67 inches (42 mm). Do you think this provides sufficient ID to allow new wires to be pulled to support an upgrade to 200 amp service, if the homeowner elects to upgrade to a 200 amp panel?

Concerning the overall load for the whole complex, when Toronto Hydro did our transformer & underground wiring upgrade in 2017, they installed new buried conduits 900 mm below ground encased in concrete running from the new local transformers (27,000 volt) all the way to the meter boxes at the front of each home, and ran new wires to the meter boxes. They also replaced all the meter boxes, which suggests to me that the new meter boxes might be designed for a higher capacity than the originals. Hence my concern is not so much with whether the neighborhood supply can cope with the load - my concern is that homeowners will need to get some serious electrical work done within their home if they want to install a Level 2 charger.

Many, many thanks to all of you for taking the time to respond. This will help me to write an accurate and credible "head's up" to everyone. I'll come back and post the text of the article here on this thread once I have sent it out to everyone.

Michael, Toronto.

Although the power company (Hydro) replaced the wiring with larger that doesn't mean they increased their transformers. So I would say if lots of people do the upgrade, Hydro would need to be informed.

 

[LarryFine]

The plastic underground conduit running from the meter box at the front of each home to the electrical panel of each home (a distance of about 30 feet, including the two vertical portions) has an OD of 1.67 inches (42 mm). Do you think this provides sufficient ID to allow new wires to be pulled to support an upgrade to 200 amp service, if the homeowner elects to upgrade to a 200 amp panel?

That's 1-1/4 Sched 40. I don't see that being large enough for 200a. Could 150a work?

 

[suemarkp]

It depends what in in those conduits -- service conductors (3 wires) or feeders (4 wires). You should be able to do 125A for sure, and probably 150A. One quirk of residential electrical calculations is that if 100A is sufficient now and you add a 40 amp load, the calculation increases by less than 40 amps (a US load calc would increase by 40% of that value, I don't know how Canadian ones work). So a 125A would most likely work for a 40A charger, but someone does need to do a calculation to make sure.

Also, if all you need is more spaces, a subpanel can be added next to the existing panel. That would work if it happens the wires are rated for 125A with the 100A main (unlikely, but possible). But if one is going to the trouble to change the feeder from 100A to 125A or 150A, I'd just replace the main panel since the wires are coming off it anyway.

 

[RumRunner]

Hello Folks:

I'm not an electrician. I have been asked to write an article for our condominium corporation newsletter to advise homeowners that they might need to upgrade their home's electrical panel from 100 amps to 200 amps if they purchase an electric car and want to install any form of charger for the car other than something that plugs into a standard 110 volt 15 amp outlet.

It's not my intention to tell homeowners how such an upgrade is done. The purpose of the article is to advise homeowners to investigate, with an electrician of their choice, exactly how much work will need to be done and to determine with their electrician what this will cost before they purchase an electric car.

Our community consists of 70 townhouses in Metro Toronto that were built in 1980. The units have between 1 and 3 bedrooms and vary between 1,500 and 1,900 square feet, including the finished basements. When the units were built, none were equipped with air conditioners, and all were fitted with 100 amp service panels. Since then, every single owner has added an air conditioner.

When I look at my service panel, which is typical of all the other units in our community, I see the following:

1. All the breaker spaces are occupied, there are no empty spaces left.
2. There is a 20 amp double breaker for the air conditioner, and two 40 amp double breakers, one for the dryer and one for the stove.
3. There are three 15 amp double breakers that service kitchen outlets.
4. The remaining twelve 15 amp breakers service lighting, the fridge, the smoke detector, and other outlets.

In 2017, Toronto Hydro upgraded all the underground wiring in our community, from the 27,000 volt transformers all the way to the individual electrical meters at the front of each home. Presumably when the new wires were run from the distribution transformers to each home's meter box, Toronto Hydro ensured that these wires could cope with more than 100 amp service, but this is a presumption, not a known fact.

Our Property Manager believes that if a homeowner wants to install a charger for an electric car (other than a 110 volt, 15 amp plug-in charger) the homeowner will need to have their electrician do the following:

1. Upgrade the size of the electrical panel from 100 amps to the next largest commonly used size (presumably 200 amps).
2. Install, at homeowner's expense, a new set of wires in the conduit leading from the electrical meter to the power panel.
3. Possibly install a new base plate for the electrical meter (this depends on whether or not the meter base plates were upgraded in 2017).

Would you folks please let me know if you think the above work will be necessary? Personally, I think our Property Manager is correct and it will be necessary to upgrade the service panel, but I don't want to put out a newsletter saying "Hey, you might be looking at some big expenses if you want to install a car charger" if that is not correct.

Thank you very much for any advice and criticism you can provide, and thank you also if you can provide me with any web links you think I should include in the newsletter article to better inform homeowners about what they need to know.

This is my first post in this CANADIAN FORUM. I rarely spend time reading the different posts.

Your post should be encouraged and no second thoughts should get in the way that might foment the slight animosity from the forum and members at large.
I think that you have articulated clearly enough.

For one thing. . . you are promoting the readers' potential patronage by saying: "to investigate with an electrician of their choice" .

A different perspective--especially from an outsider is essential in widening our knowledge in every endeavor we pursue.

Diversity is what everyone needs to become truly competitive in this trade. . .in this day and age.

If people think the same way as everyone does--no one is thinking.

That was a quote from a well-known general during the European campaign in WW II.

General George Patton.

Also, by confining ourselves in an enclave where there is no diversity--we become senile. lol
So, keep writing away to extricate us from this boredom--brought on by COVID.
I love reading pieces with QUALITATIVE substance.

And going back to your question:

The existing 100 Amp will put you in an allowable amp rating that will accommodate the charger. . . that is-- by applying a demand load factor that is often used (or can be used) by the designer--based on the information you provided.

Good luck with your essay.

 

[BillyMac59]

For what it's worth...I recently had a brief conversation with an ESA inspector on this very subject. He said that one of the prerequisites for pulling a permit to install a charger is that a 200A service is in place. People have had too many power problems when charging anytime other than overnight. even then, some people have issues ie electric furnace on cold nights running at the same time. As for underpowered community transformers...my town has already begun experiencing this. I won't be surprised if somehow municipalities get involved in the installation process.

 

[ramsy]

If Canadian electrical code allows historical demand calcs based on utility records, similar to NFPA-70 220.87, fuse box upgrades become an unnecessary-construction gimmick, especially if natural gas is already used for major appliances / heating, and if twins or Quads can make room for a 2-pole breaker.

The real question, "is a dedicated Meter for the electric car needed for energy credits & rebates", and if consumers wan't those credits. If adding another meter center for car charger energy credit, it will come with its own 2-pole breaker disconnect for the car charger.

Therefore, with dedicated meter, upgrading existing fuse box with nothing new going in there is ridiculous, even if AHJ or Canadian ESA inspector ignores gas appliances and historical utility records, to impose a 200A feeder for the permit.

 

[tom baker]

If the condos have an lower or basement level garage, consider installing an electrical service just for EV charging. Submetering is easily done for each tennant space. Add in a surcharge for the overhead costs

 

[tortuga]

Hello Folks:

I'm not an electrician. I have been asked to write an article for our condominium corporation newsletter to advise homeowners that they might need to upgrade their home's electrical panel from 100 amps to 200 amps if they purchase an electric car and want to install any form of charger for the car other than something that plugs into a standard 110 volt 15 amp outlet.

It's not my intention to tell homeowners how such an upgrade is done. The purpose of the article is to advise homeowners to investigate, with an electrician of their choice, exactly how much work will need to be done and to determine with their electrician what this will cost before they purchase an electric car.

Our community consists of 70 townhouses in Metro Toronto that were built in 1980. The units have between 1 and 3 bedrooms and vary between 1,500 and 1,900 square feet, including the finished basements. When the units were built, none were equipped with air conditioners, and all were fitted with 100 amp service panels. Since then, every single owner has added an air conditioner.

When I look at my service panel, which is typical of all the other units in our community, I see the following:

1. All the breaker spaces are occupied, there are no empty spaces left.
2. There is a 20 amp double breaker for the air conditioner, and two 40 amp double breakers, one for the dryer and one for the stove.
3. There are three 15 amp double breakers that service kitchen outlets.
4. The remaining twelve 15 amp breakers service lighting, the fridge, the smoke detector, and other outlets.

In 2017, Toronto Hydro upgraded all the underground wiring in our community, from the 27,000 volt transformers all the way to the individual electrical meters at the front of each home. Presumably when the new wires were run from the distribution transformers to each home's meter box, Toronto Hydro ensured that these wires could cope with more than 100 amp service, but this is a presumption, not a known fact.

Our Property Manager believes that if a homeowner wants to install a charger for an electric car (other than a 110 volt, 15 amp plug-in charger) the homeowner will need to have their electrician do the following:

1. Upgrade the size of the electrical panel from 100 amps to the next largest commonly used size (presumably 200 amps).
2. Install, at homeowner's expense, a new set of wires in the conduit leading from the electrical meter to the power panel.
3. Possibly install a new base plate for the electrical meter (this depends on whether or not the meter base plates were upgraded in 2017).

...

My understanding of the canadian code is a 24 circuit panel with no electric furnace is limited to a 100A [CEC 8-108 1) b)].
If you have new 125 Amp feeders to the condo's you could upgrade the panels to a 125A 30 Space and add the 240 volt EV branch circuit.

If Canadian electrical code allows historical demand calcs based on utility records, similar to NFPA-70 220.87, fuse box upgrades become an unnecessary-construction gimmick, especially if natural gas is already used for major appliances / heating, and if twins or Quads can make room for a 2-pole breaker.

The real question, "is a dedicated Meter for the electric car needed for energy credits & rebates", and if consumers wan't those credits. If adding another meter center for car charger energy credit, it will come with its own 2-pole breaker disconnect for the car charger.

Therefore, with dedicated meter, upgrading existing fuse box with nothing new going in there is ridiculous, even if AHJ or Canadian ESA inspector ignores gas appliances and historical utility records, to impose a 200A feeder for the permit.

Yeah it does, you would need to do a demand study on each condo:

Where additional loads are to be added to an existing service or feeder, the augmented load shall
be permitted to be calculated by adding the sum of the additional loads, with demand factors as
permitted by this Code, to the maximum demand load of the existing installation as measured over
the most recent 12-month period, but the new calculated load shall be subject to Rule 8-104 5)
and 6).

86-302 classifies the EV charger as a continuous load

 

[tortuga]

Actually if these all have 100% non-electric heating and water heating, AC unit nameplate is 16 amps or less, and no unit is over 177m2 (~1900 SQFT)
It might work out on a 100A:

8-200 Single Dwelling Calc​	m2​	VA​
a)​	​	​
m2​	177​	​
First 90m2​	​	5000​
m2 over 90m2​	87​	1000​
Range (not over 12kW nameplate)​	​	6000​
Air conditioner​	​	4000​
Electric vehicle supply equipment​	​	8000​
​	​	24000​

But then you would need to do the voltage drop calcs.

 

[ramsy]

We have 1960's track homes with 50A fuse boxes still in use. 4 bedrooms built with gas appliances, and dedicated 20A electric space heaters in 2 bathrooms. Natural gas heating, cooking, & laundry appliances.

We also have 1970's custom homes with gas lines that skip the kitchen, on their way to a BBQ pit in the back yard, built with 125A fuse box for the electric-cooking appliances.

By the 1980's Government/Reagan's budget cuts & prop.13 property tax cuts defunded local authorities, so building planning & permit practices were less regulated or consistent in California & perhaps other states.

 

[Eddy_Current]

Easy solution is to add an EVEMS. These devices will not allow the car to charge if too much power is being used in the dwelling. They are not cheap, ($1000 loonies) but cheaper and easier than upgrading the service. Here is a link to one

Common one used in Ontario

 

[zbang]

With the cost of those devices, it's probably better to upsize the service anyway, especially if it's an old panel.

 

[Eddy_Current]

With the cost of those devices, it's probably better to upsize the service anyway, especially if it's an old panel.

I agree it would be better, but customers don’t go for it when you give them both options.

A new service would be double or triple the cost of one of those devices.

In the OP’s situation the feed to the meter base, the meter base, the feed to the panel and the panel would need to be replaced. Huge difference.

Also if many of the occupants in the community started increasing their service size, the supply from Toronto Hydro might not be enough supply them. If they installed an EVEMS there is no worry of that.