Can I add a 100A circuit for HPWC?

[SteveW25561]

I've ordered my MS 85 with dual chargers...now comes the painful wait for the car! But in the meantime I can install the charger.

I want to install the HPWC with the full 100A circuit.

Here's my electrical panel: can I add a 100A circuit to it still? The house is 8 years old, and note subpanel (? is that 200A -- it's inside the house and deals with the kitchen, bedrooms, etc).

Thanks!
- Steve

 

[milotron]

Hi Steve, from across the water in Victoria!

I would say that you are out of luck for adding a 100 amp circuit. Your 125 amp main breaker can only be loaded to 80%, even without considering the other loads in the house. I suspect that you have gas heat...To be honest, even adding a 50 amp circuit for the HPWC may be pushing your luck for total capacity. You will need somone to review this as it appears to be close to fully loaded. ( I am an electrical engineer and electrician, but this is an arm lengths opinion! )

 

[SteveW25561]

Oh no!

How would I add the 100A circuit? Would I need another electrical feed from the city?

And yes we use radiant heat/natural gas.

I have no idea what I'm looking at but what does it mean when there are 2x125A breakers tied together with the metal band (or the 2x100 and 2x30) ?

Btw hi to a local British Colmbian!

 

[Cosmacelf]

That's your main breaker panel, right? So it looks like you only have a 125 amp service - ir. the maximum load you can draw is 125 amps (at 240V) from the panel. Do you have any air conditioners? Pool pumps?

Here's the deal. An electrician has a formula for doing load calculations to see how loaded your panel really is based on what loads you are using. All those 15 and 20 amp circuits are usually lumped into a general estimate load pool that is based on the square footage of your house. They then start adding up the loads from the big consumers, which would be your range/stove (electric?), dryer and any other loads that use two legs (for example that dryer).

But frankly, it doesn't look good for an HPWC. Lets say the dryer uses 24 amps, a stove/oven when on might use 30 amps - well right there we have 30+24+80 (for the HPWC) = 134 amps which will easily exceed the 125 main panel rating.

So you have two choices. Don't install the HPWC, but Milotron is right, even adding a 40 amp 240V circuit will be pushing it depending on what else you have - a quickie load calc would tell you what you can do there.

Otherwise, you can upgrade your service from the power company from 125 amps to 200 amps. There are two parts to that. Hopefully your panel itself is a 200A panel. If it only rated at 125 amps, then that would require a new panel, figure a couple of thousand dollars minimum there for that. Then the power company needs to upgrade the service which is very doable, but the cost there completely depends on their tarrifs, etc.

 

[SteveW25561]

Ok, thanks for the insights.

Our main big draws are the dryer. There is one ac unit. The stove and oven are gas. Heating is gas.

The Ouse is over 3800 square feet. I guess all the gas appliances is why they have such a small main box for this place. Never gave it a thought until ordering the tesla!

Guess ill be calling the electrician tomorrow,

 

[SteveW25561]

Ok, now here's a second situation. We have a cottage and all I want there is the 14-50 outlet. A this place, heating is electric, hot water heater also electric. Stove is gas.

Here's the breaker there. Can I do the outlet?

 

[milotron]

the cottage may be the same deal, although the exisitng loads are not clear, it looks like lots of heat.

Call BCHydro tomorrow as to what a 200 amp service upgrade to your house may costs. it depends if your service is overhead or underground, plus this will also impact the electricians costs. Unless you need a really quick turn around for charging, the 50 amp connection will give you plenty; it has not been an issue for me yet.

The canadian electrical code got sticky for EV chargers late last year requiring a greater allowance in the load calculation and a seperate disconnect switch when the connector is larger than 60 amps.

 

[SteveW25561]

Thanks again for the opinions.

Again at the cottage all I need is the 14-50, not the HPWC. The service is underground there so it might be a pain to upgrade. We're up at Cultus Lake.

Since I might end up just using the dryer outlet at the cottage until I figure this out, I wonder if I install the 14-50 to the pictured breaker and just always remember to never use the dryer and the 14-50 at the same time, I'd be ok? Or would the presence of that outlet violate code?

As you can tell I'm totally ignorant about these things.

I'll be making a few calls tomorrow!

 

[Mayhemm]

I'm in the same situation as you, Steve. Our house service is a bit of a mess (we have a 200A main panel with 3 sub-panels).

I ended up just having a second 200A service run to my garage. This will support our two EVs plus everything else I need in the garage (power tools, lights, heating, etc) without issue and it's a heck of a lot simpler. Mind you, our power lines run above ground, so they really just had to string a line from the pole outside my house. No digging or anything required.

 

[FlasherZ]

Ok, thanks for the insights.

Our main big draws are the dryer. There is one ac unit. The stove and oven are gas. Heating is gas.

The Ouse is over 3800 square feet. I guess all the gas appliances is why they have such a small main box for this place. Never gave it a thought until ordering the tesla!

Guess ill be calling the electrician tomorrow,

It may be as simple as a new service entrance cable, and a new main breaker, if the drop to the house can support a higher rating. Good luck with the electrician.

- - - Updated - - -

Ok, now here's a second situation. We have a cottage and all I want there is the 14-50 outlet. A this place, heating is electric, hot water heater also electric. Stove is gas.

Here's the breaker there. Can I do the outlet?

It's hard to tell from that shot without a listing of breakers, but I see some markings that would lead me to believe you'd need an upgrade there too, as the 40A continuous load is going to suck up a good chunk of your service.

(Those same EV load calculations mentioned for Canada will change for the US as NEC 2014 is adopted across the country.)

 

[Cosmacelf]

Since I might end up just using the dryer outlet at the cottage until I figure this out, I wonder if I install the 14-50 to the pictured breaker and just always remember to never use the dryer and the 14-50 at the same time, I'd be ok? Or would the presence of that outlet violate code?

You mean wire a new 14-50 receptacle in tandem to the 30A dryer breaker? Bad idea, even if you could fit two heavy gauge wires into one breaker lug. A better idea is to simply get a new 50A breaker and pop it in (you have extra slots) and wire a new 14-50 receptacle to that. The issue here is whether or not you are in danger of exceeding your 125A panel rating. Those 15A and 20A 240V breakers (the double wide ones are the 240V ones) are probably for baseboard heaters? If so, and you use the the cottage during the spring/winter/fall when heat will be on, then you might be pushing it. It isn't so much a matter of safety since if you did exceed the 125A main breaker load, all that SHOULD happen is the 125A breaker would trip and turn off all the electricity in the cottage.

Again, without doing a proper load calc for the cottage, it is hard to tell if you could add a 50A load and get away with it. An electrician could tell you. You could always put in a 30A breaker and install a NEMA 14-30 (and get the Tesla adapter for it) for a slower charge and lower load.

 

[FlasherZ]

You mean wire a new 14-50 receptacle in tandem to the 30A dryer breaker? Bad idea, even if you could fit two heavy gauge wires into one breaker lug.

With very few exceptions, double-tapping a breaker is against code in the NEC, I believe the same is true for the CEC.

Also, in the US, it is legal to connect multiple receptacles on a single branch circuit; HOWEVER, the receptacle ratings are limited. US NEC 210.21(B)(3) specifies that when the branch circuit is a 30 amp circuit and multiple receptacles are connected to it, only 30A receptacles may be used. US NEC 210.23 also states that connected loads may never exceed the rated branch circuit capacity (meaning, you are not permitted to connect the Tesla UMC with the 14-50 adapter to a branch circuit smaller than 50A).

Seek appropriate guidance via an electrician for the CEC.

 

[SteveW25561]

Thanks for all the replies.

To be clear, all I was thinking of was to install a NEW, separate 50A breaker with the NEMA 14-50 plug, then remember to never run the dryer and the car charging at the same time to avoid overloading the whole breaker box. The dryer circuit would remain untouched. I was just thinking of the overall load.

The suggestion to just install another 30A circuit with another NEMA 14-30 plus the requisite adapters would be a good potential solution. I would still avoid running the dryer at the same time.

I'll be contacting electricians today -- I just got my delivery window of Aug 3-17, so I might need this sooner than I thought!

 

[FlasherZ]

Thanks for all the replies.

To be clear, all I was thinking of was to install a NEW, separate 50A breaker with the NEMA 14-50 plug, then remember to never run the dryer and the car charging at the same time to avoid overloading the whole breaker box. The dryer circuit would remain untouched. I was just thinking of the overall load.

The suggestion to just install another 30A circuit with another NEMA 14-30 plus the requisite adapters would be a good potential solution. I would still avoid running the dryer at the same time.

I'll be contacting electricians today -- I just got my delivery window of Aug 3-17, so I might need this sooner than I thought!

Good to hear. Your electrician will be able to look at your individual loads, or you can use a widely available load calculator spreadsheet online, to determine what your service size would need to be for various options (24A continuous load on a 14-30, or 40A continuous load on a 14-50, or whether you need a service upgrade altogether).

I don't know the situation with the power company where you live, but in my neck of the woods, with the exception of replacing the meter pan, service conductors, and upgrading the main panel as appropriate, the power company bears the costs of the upgrade. Your electrician can guide you. Good luck!

 

[Cosmacelf]

Ah, sorry I misunderstood. Yes, not running the dryer to mitigate potential load problems is a good idea. It'll work until your wife forgets

Actually even then, you probably wouldn't run into a problem. Load calcs assume every 240v load is on at he same time, which rarely happens. But it may happen once in a while.

 

[Ampster]

I remember seeing something about some "smart" devices that did not turn on when the load on the panel exceeded a set value. I recall something about them needing a smart meter and, if i remember correctly, they were expensive. Recently I tried to find that again with no luck.

I have a similar situation to those discussed above and the most cost effective solution for me may be to replace my electrice dryer with a gas one.

 

[dhrivnak]

Getting back to your intial question of adding 100 amp service to your 125 amp panel. IF the wires into your house are rated for 200 amp service which seems to be the minimum now in the states, and your current box is 200 amp service with just a 125 amp main breaker then I believe you can upgrade with minimal costs. In my area they only sell 100 amp, 200 amp and 400 amp panels and I would guess you likely have a 200 amp panel. I would assume the wiring to your house is rated for 200 amps and if so you have room to add a 100 amp breaker and then you would need to upgrade the main breaker to 200 amps from 125A. But as many cautioned check with an electrican unless you can measure the guage of the incoming wire.

 

[Vger]

If your situation is marginal, as it appears, be sure to check with BC Hydro, as others have said. At least one Tesla owner had a pretty scary night due to a situation like this:

Incoming utility cable capacity - A cautionary tale

Greeting from across the Strait... welcome to TMC and soon to owning a treasure of a car!

 

[SteveW25561]

Well, just got some quotes and its not pretty.

I'm currently facing a need to upgrade my 100a service to 200A because my main breaker box doesn't have enough capacity to do the HPWC at 80 or 100A. The quotes I just got are over $4000 CDN to do this since it involves changing the breaker box to 200A. Just the breaker box upgrade is around $2000 which seems high considering a brand new 200A box at Home Depot is under $200. I know there's labour but 10x?

I also wonder if I'm being ripped off on just the surface mount wiring: he quotes $950 to run around 50 feet or so of 100A wiring on the inside of the garage from the breaker to the outer wall location I planned for the hpwc. That seems like a lot of money just for cable and labour on this part.

The electrician said even if I just added a 50A outlet, my load calculates to 105A, exceeding the max allowed 100A out of 125A.

I don't drive a lot during the week so the HPWC is more luxury than need, but since the BC government is offering a $500 rebate on these it makes the price the same as a new mobile connector with the convenience of a cable that won't get stolen or plugged/unplugged daily.

What if I do this: just install a 40A breaker on the existing house service, then just set the HPWC to 40A? Would this get me below the 100A ceiling? (My uninformed calculation puts me at 95A total @ 40A vs 105 @ 50A, but I don't know if its this simple).

If I need more I'll bite the bullet for 200A. It feels hard to justify $5000 just for a charging circuit (there goes any potential savings vs gas!).

FYI I tried asking BC Hydro if I could just run a new second 100a line to the house (and installing a dedicated 100a breaker just for the Tesla) which would also give me a way to directly measure the Teslas energy use and cost for tax reasons. They said no, and would only install a second 100A feed if we had a second suite in the home. My only option is apparently a 200a upgrade, thus back to square one.

 

[Doug_G]

Get several quotes; you can get quite a range.

Unfortunately upgrading your service IS expensive. The utility has to disconnect your service, then reconnect it, and they charge big bucks for that (because they can!). The wiring from the meter to the panel has to be upgraded. Every circuit in your panel has to be disconnected, and then reassembled in the larger box. That's quite a bit of labour.

As for running the wire, cable of that capacity is not cheap, and its also awkward to work with. So it's gonna cost some bucks.

See if you can find an electrician willing to put in a 50A circuit. You can still use the HPWC with the current setting dialed down to 40. You don't really need uber-fast charging at home and this will be a lot less expensive.