Mini splits in cold weather, and an electrical question

[Zachary Hoyt]

I've read a number of threads on the Workshops forum in which people spoke very highly of mini-split air source heat pumps, and I am wondering about getting one for the house I am planning to move into next year. It is in the town of Piercefield NY, in the northern Adirondacks, where it gets pretty cold in the winter. I have read about cold climate mini splits but don't know anyone who has been using them up in these parts. The house is 950 square feet officially, actually a bit smaller on the inside, and the downstair is almost completely open. I am planning to use a wood stove for primary heat in the winter, but it would be handy to have backup heat and AC for the milder seasons. If anyone has experience with the cold climate mini splits I'd be interested to hear about it.

I've gutted the house almost completely, and will be insulating it with R15 rockwool in the walls and R38 in the attic, and probably R30 under the first floor since the basement is stone. The house has a pretty new 100 amp panel box and service entrance, so I am hoping I can get by with that, using an electric stove and with a 30 amp sub panel in the workshop I will be building. I don't have any idea how much power a mini split requires, and if it is feasible to add one to a 100 amp service or if I would need to upgrade to 200. My understanding of theoretical electricity is limited, so I don't understand how to tell what is a reasonable load for a given size panel. Electricity seems simpler to me than propane (natural gas is not available) and also cleaner in terms of indoor air quality for supplemental heat,domestic hot water and cooking, but I don't know a lot about the relative merits or how much power is needed for a 2 bedroom 1 bath small house. If anyone can advise me on what I should do I would very much appreciate it.

[John K Jordan]

I know nothing about mini splits or mini splits in cold weather but I have heat pumps in this house and shop and have had several in previous houses.

Heat pumps are widely used in milder climates such as here in TN. However, the average temperature in the coldest part of the winter here is still above freezing, much warmer than your area. I understand heat pumps lose efficiency below 40 degrees.

The problem is heat pumps extract heat from the outside air and when it's too cold outside that simply can't extract enough heat to be useful. At some point, built-in electrical resistance heaters cut in and the energy use spikes. Here we don't have many days with that happens but when it does I can see it in my electric bill. Better insulation helps hold that heat, of course, minimizing the extra cost.

Even in this climate I keep my thermostats low in the winter and high in the summer due to the cost of electrical power. If I had gas run to the house I'd be tempted to use that for aux heat. I have no idea - maybe there are hybrid gas/electric heat pumps.

As for the load for a panel I add up all the expected loads and make sure they are below the amperage rating of the panel. This is a lot easier in the shop since I don't often have multiple heavy current users operating at once. (I installed 100 amp box and have never measured above 20) In the house I have a 200 amp panel. The breaker feeding my heat pump is 100 amps - it's a large commercial unit. I've never measured the actual current drawn.

I'd certainly ask a few local heating suppliers to see what's reasonable in the area. Your state may also have educational resources.

JKJ

[Jack Frederick]

You can get mini-splits that will work at their rated capacity down to -20*f. That would be the Hyper-heat by Mitsubishi and other manuf have them without the specific handle. You must make sure that you are getting the right unit. My units will work down to 5*f which we never see here so it is all good. Install it on a wall rack or a free standing rack. Taht will keep it cleaner and keep it from turning into an ice cube when you get a clipper off the lake. Make sure you have an installer who has been to the factory trainings. If they are not that well known in your area, find the right person for the install. They do work. You absolutely cannot compare the deep heat mini-split heat pumps to the conventional heat pumps in central systems we know today. They are much more efficient. The alternate for a mini-split would be a Rinnai Energysaver direct vent wall furnace, either NG or LP. An EX22 (8200-21,000 btu) would be my choice if you button the place up. The EX38 would fire (13,000-38,000) and absolutely heat the place.

[Steve Demuth]

We heat and cool our guest house with a mini-split air source heat pump. This is in NE Iowa, where average temperatures range from the single digits to low 20s for a solid 4 months of the year, and absolute lows frequently reach -20oF for multiple days at a time in late December through early February.

The best air source heat pumps available today cannot heat a space at all when the outdoor temperature goes below about -15oF, and they are pretty darned expensive and inefficient to run much below 15oF. So, for this to be a viable solution in a climate like ours, you need a very tight, very well insulated house. Our guest house is 600 ft2,built new in 2018. It is insulated from the sill plates on up with 5" (walls) and 9" (ceiling) of blown in closed-cell foam insulation, and has top of the line Marvin high thermal efficiency windows and similar doors. It's tight enough that we require powered air exchange to control humidity and keep the air quality up. The heat pump still cannot fully heat the place when we get a week of high plains "Alberta Clipper" weather, when daytime highs may not go above the low single digits and nighttime lows are routinely in teens below zero, for a week or more. We deal with those by closing the place down and not heating it during such weather. If it were occupied all the time, we'd have to have supplemental heat (I built it with dual-use, gas, on-demand hot water heater that could provide baseboard radiant heat, e.g., if we wanted it). The heat pump is rate 9000BTUs and is on a 15A breaker.

We used $200 - 250 worth of electricity to heat the house during each of the last two winters. It wasn't heavily occupied, though, due to Covid. I imagine that if it were regularly occupied, that might double.

My general take is that air-source heat pump is a marginally viable option for our climate. It only makes sense in construction that can be very tight and well insulated. If I were combining it with wood heat, I would insist on a very well designed and carefully installed, external combustion-air wood setup. The degree of infiltration control you need to make the heat pump a viable solution is not compatible with casual wood stove operation.

[Kevin Jenness]

Zachary, I have Mitsubishi Halcyon 18k btu heat pumps in both my house and my shop in a similar climate to yours. Our units are rated at 17 amps/220 volts. We had wood heat as our primary (only) source for decades and typically burned 2- 2 /1/2 cords in the house and 1-1 1/2 in the shop. We still burn wood but less as the heat pumps are primary now, and we rarely burn wood in the shoulder seasons. They function down to -15 F, but are less efficient the lower the temp and in severe weather have to cycle between heating the building and melting ice off the coils. Still, they are less expensive to run than the common alternatives here like propane, oil or kerosene, and we generate a bit more electricity than we use with pv panels so we use fossil fuels only for cooking, seasonal water heating and driving.

Since you have the house gutted take the opportunity to insulate as much as you can. It will pay off over time. My 1100 sq ft shop has R19 fiberglass (rockwool or high density cellulose would be better) plus an inch of rigid foam (~R5) on the interior walls and R38 in the ceiling and roof which performs better then the R25/R44 fiberglass in the 2200 sq ft house. If you can get a layer of foamboard on the exterior of the house that would be good and easier to seal air leaks than on the inside.

I wouldn't rely on the heat pumps as the sole source of heat in this climate, but we do fine with supplemental wood heat. Air exchange in the house is handled with wall vents and a bath fan on a timer.

I would recommend having an HVAC engineer do a heat calculation so you can size the heat pump properly. Too small and it won't keep you warm, too large and it will run inefficiently. Most of the vendors I met with were relying on educated guesswork for sizing the units.

[Zachary Hoyt]

Thank you all very much for your insights. There's a lot of information here to think about. The exterior of the house has aluminum siding which is in good shape, so I am reluctant to take it off to add insulation. The wall framing is rough cut 2x4s, so I am figuring I can do r15 rock wool, or maybe look into closed cell spray foam, but I think that would be a lot more expensive. I am not planning to stay in this house more than 5 years or so, most likely, as my eventual goal is to build a passive solar house with better insulation on a larger piece of land. I grew up in a passive solar house in Maine till I was 15, and we burned 2-3 cords of firewood a year for heat at night and on cloudy days. I'm not sure how much it makes sense to aim for maximum insulation in this house given the short period of time I plan to be there. Most of the house had no insulation previously, so I figure that batts will be an improvement, but I need to look at other options too.

[Ronald Blue]

When you say rock wool do you really mean fiberglass? Just curious. As for the attic You will never regret going higher. Maybe R-50 or so. If you don't plan to stay long term do blown in cellulose. Blown in is more effective whether it's cellulose or fiberglass.

[Zachary Hoyt]

Rock wool is better than fiberglass in several ways, but also more expensive. I don't see a benefit to blown insulation in my situation where I have full access to all the cavities to be filled. I have understood that it was more useful where someone wanted to insulate without tearing out the walls. Maybe there's something better about it that I don't know about, though.

[Jim Becker]

Mini-splits are pretty adept at dealing with the cold if you choose the right unit for your climate. Your initial cost goes up a little for the super efficient units that can derive heat at very low temperatures, but it's still a valid option compared to even a few years ago. The unit in the shop at our old property was good to -5ºF. As someone mentioned, there are units available that go impressively lower. And having that wood stove means you have productive heat available if outside conditions deteriorate to the point that the split starts to get challenged pulling heat out of the air. In the meantime, you have a reliable way to keep conditions nice and, of course, great AC and dehumidification during the warmer months.

Mini Splits typically use a 20 amp or 30 amp 240v circuit, but the specific unit will need to be considered for power requirements and a larger, multi-head setup may or may not require more. 100 amp service is very light these days and power companies/jurisdictions don't permit lower than 200 amp for new/remedial service connections.

BTW, I'm all about paying really good attention to insulation and sealing the envelope. Do keep in mind that since you'll be burning wood for some of your heart, you'll need to provide for makeup air during those times if you properly insulate and seal the building.

[Zachary Hoyt]

Thanks, that's good to hear about the viability of the newer mini splits in cold weather. There is currently no power to the house, it was shut off in 2015. I just looked it up and our local utility will connect a 100 amp service for a house, but nothing smaller. I'll have to make inquiries into what it would cost to upgrade the service to 200 amps. I am planning to buy a stove which comes with an outside air kit, so that the combustion air is drawn from outside the heated envelope. If I increase the electric service I could use electricity for cooking, heating/cooling and hot water, which would be nice since natural gas is not available.

[Jim Becker]

Given you need electrical service hooked up, I'd upgrade to 200 amp, which is the current residential minimum standard, personally. And yea, you have good reason for that, too. If I recall clearly, you may have said this is a "stepping stone" (my words) property for you until you are able to get what you really want. 200 amp electrical plus your improvements will make this place more saleable/desirable for future occupants and certainly be a better fit for a residence plus a shop. The power company may not even need to change the drop from the pole, depending on how old it is, so conversion to 200 amp service is the house end of the drop and a new panel primarily. It should be reasonable in cost, IMHO, and more than pay for itself.

[Zachary Hoyt]

Thanks, that's something I definitely need to look into. I need to rewire the whole house anyway, it still has some old cloth covered wiring that was hooked up, and the new wiring is not run properly.

[Dave Zellers]

Agree 100% with 200 amps. The future is electric!

Weren't they saying that back in the 50's? :D

[Jim Becker]

Thanks, that's something I definitely need to look into. I need to rewire the whole house anyway, it still has some old cloth covered wiring that was hooked up, and the new wiring is not run properly.

Yea, deal with electrical and plumbing right from the start for both safety and functionality. All else is mostly to "look pretty"...

As an aside, I had to take care of three wiring situations in this new-to-us house since moving in and they got priority. It seems the previous owner liked to splice wires in the wall with wire nuts and tape while moving outlets around merely by ripping them from the wall and plopping them (unsupported) into a new hole. Yea. He did that. Our old house had a big mix of wiring types dating back to the "dark ages" (no knob and tube) but it was at least all done correctly and safely.

So take the time to examine everything you can carefully! You never know what you'll find.

[Malcolm McLeod]

Mini-splits (or any air-source heat pump in general), do poorly in extreme cold - as several responders have pointed out. If this is an issue, then you might consider ground-source heat-pumps. Another dimension of installed cost, but will leave that to you and your accountant.;)

[Zachary Hoyt]

I've removed all the wall coverings (drywall, plaster, weird old brown flaky sheet material, lath etc) and the downstairs ceiling, so I have full access to all wiring and plumbing now. I'm planning to replace everything. The wiring is a mess, the supply plumbing was allowed to freeze and burst 6 years ago, and the drain pipes are mostly cast iron and need to go before they fail. It'll be a fair bit of work, but when I'm done I will know what's there, and I'll take and back up lots of pictures for my own future reference and to pass on to a new owner someday, so they can find things if they need to.

I'm also going to go ahead and have a new septic system put it, since the old tank is metal and was put in about 60 years ago, 3 or 4 feet deep, somewhere in one part of the back yard. The whole neighborhood was done with these metal tanks at about the same time when the town sewer system was closed, and some of the others have rusted away so I assume mine is or soon will be too rusty to be safe. Also there's a collapsing wall in the basement, likely due to the roof leaking on it for years, so I am waiting for quotes from a couple of masonry/stonework folks.

It'll be an adventure, but with the real estate market as crazy as it is this is what seemed to make the most sense. I could have spent around 80k on up to buy one of a few houses that were technically livable but still needed some work, so buying this for 23k and putting in the money to fix it to a higher standard seemed like a better plan.

[Ed Aumiller]

Since you are going to be replacing the septic tank, you will have a backhoe already there...
Seriously consider burying about 1500-2000' of 1" black plastic water pipe and putting in a geothermal system...

You can loop the pipe like a slinky toy to save space digging..
(this is what I did on my son's house)

You can buy the geothermal unit (new) on ebay and do everything yourself. They are sealed units and can be installed without
a license. The efficiency stays constant through out the whole year.... The cost is only slightly more than a normal heat pump.
For a house that size, a 2 or 2.5 ton unit would probably be about the right size.

Installed one in my house over 25+ years ago and one in my son's house 15+ years ago... The new ones have a built in water pump
and all you need to do is connect the water lines using 3/4" fittings.
Recommend you do not have any joints in the lines outside.. You can buy the pipe in LONG sections.. I used 700' sections on my house.

[Steve Demuth]

Since you are going to be replacing the septic tank, you will have a backhoe already there...
Seriously consider burying about 1500-2000' of 1" black plastic water pipe and putting in a geothermal system...



This for sure. If you're going to be doing the digging and underground plumbing, then ground-source heat pumps are the way to go for energy efficient heating and cooling.

[Zachary Hoyt]

I have only a 9700 square foot lot, so I don't think a ground source system will be feasible for now. In a future house build it's certainly something I'd want to look into, though. Aside from the small size of the lot there is also a town water line running across the middle of the lot, and what some people have told me may be an outcropping of bedrock in the back yard. The Adirondack region is pretty rocky in general, so this is quite believable. It's a compromise, not quite what I want for the long term but suitable for a while, I hope.

[Ronald Blue]

Rock wool is better than fiberglass in several ways, but also more expensive. I don't see a benefit to blown insulation in my situation where I have full access to all the cavities to be filled. I have understood that it was more useful where someone wanted to insulate without tearing out the walls. Maybe there's something better about it that I don't know about, though.
I mean blown in for the attic. Not the walls. Correct me if I'm wrong but I don't think I am. You will have to add a vapor barrier to mineral wool where fiberglass is available craft faced.

[Ronald Blue]

I have only a 9700 square foot lot, so I don't think a ground source system will be feasible for now. In a future house build it's certainly something I'd want to look into, though. Aside from the small size of the lot there is also a town water line running across the middle of the lot, and what some people have told me may be an outcropping of bedrock in the back yard. The Adirondack region is pretty rocky in general, so this is quite believable. It's a compromise, not quite what I want for the long term but suitable for a while, I hope.

They also do ground source with bored wells to circumvent inadequate area for a horizontal grid. I'm not convinced the payback is there personally. Large upfront investment for ground source systems. My sister in law has the well system. She's had it for 10 plus years. While it functions adequately her savings aren't enough to offset the upfront cost.

[Ed Aumiller]

Concerning Geothermal Systems:
The well method is expensive... burying the pipe is cheap and does not take that big of an area... the system I put in for my son is about 20'x40' in ground area to loop the pipe, it is a 4 or 4.5ton system... it is not necessary to spread it out like some contractors say... main thing is depth...where it is a constant temp.
My system takes up about the same area (or less) ...for a 3.5 ton geothermal system, I have 2100' of pipe (3 lines each 700')....

Because it is now popular and in vogue, contractors have unrealistic prices... the system I put in for my son was estimated at $20-25,000... it cost us less than $5000 total to do it ourselves...

[Brian Elfert]

Because it is now popular and in vogue, contractors have unrealistic prices... the system I put in for my son was estimated at $20-25,000... it cost us less than $5000 total to do it ourselves...

Even a dozen years ago Geothermal was being quoted for similar prices to what you listed, but in my case that included duct work as the quote was for new construction. I think contractors are unlikely to price competitively when the federal government is paying up to 30% of the cost in the form of a tax credit. I paid about $21,000 for duct work, gas furnace, gas piping, and ventral A/C for an existing house that had electric baseboard heat. I think the price was high, but the general contractor selected the HVAC contractor.

Does that $5,000 price include the geothermal heat pump? If so, that seems really inexpensive for a geothermal system. It seems like the heat pump and all the required bits and pieces would cost more than $5,000. I would like to do geothermal for my next heating system, but I would really like to do dual fuel as my utility has a 50% discount on electricity if you have dual fuel. My problem is I don't have the space to keep my furnace and then add the geothermal heat pump. I would likely need an outdoor geothermal heat pump to do that.

[Jim Becker]

I'm surprised that the local jurisdiction didn't force the septic upgrade!

Starting with a clean slate by gutting was a good choice, IMHO. You can not only deal with proper wiring and plumber (go PEX rather than copper...) but you can also identify any structural issues from weathering, etc., and deal with them easier than while trying to preserve finishes.

[Ed Aumiller]

(Does that $5,000 price include the geothermal heat pump?)

Yes, price included geothermal heat pump...
After 26 years the geothermal unit developed a leak.. I replaced it last spring with a new unit 3.5 ton high efficiency for $3500 from an established dealer off of ebay. Shipping was less than $200. If you buy from / deal with contractors, price is higher..
Also, I received over $1000 tax credit, cost was actually about $2700.

Please note that there are only a few companies that make geothermal. But they put various names on them. Same exact systems..

[Bill Dufour]

Since you are replacing all the electrical I will say choose one make and model of breakers. This will allow you to mix and match as work progresses.
Personally I like square D QO breakers still being made 70 years later. Lots of good used ones on the bay. You can buy a used loaded panel and save lots of money.
If you wait long enough you can get a panel with breakers for slightly more then the cost of the new panel.
Bill D

[Charlie Velasquez]

If new construction, consider a larger than 200 amp panel. My son and daughter-in-law are building. Main panel, + sub in the garage for two plug-in cars (one hybrid and one tesla), plus one attached workshop (stealth gloat for my son and wife). His electrical contractor recommended a 325 amp service, then discovered it cost about the same for a 400 amp service.

With the new code for an exterior disconnect, the layout is
400 amp exterior main disconnect
200 amp sub in the mechanical room for house proper
125 amp sub in the garage
100 amp sub in the workshop

[Zachary Hoyt]

Thanks, there's lots to think about for potential new construction someday. The jurisdiction seems pretty calm about things, though they do require an engineer to design a new septic system or a tank or leach field replacement. One engineer I spoke to said he would just wait and use the existing system until I had a problem, but I would rather get it done right and do it before I am living there, so that I don't get into a pickle later on. The town has a population of about 300, and an average population density of under 3 people per square mile, so there is not a full time code enforcement officer. I just happen to have bought a house in one of the two little blobs of village life dropped into an otherwise quite unpopulated landscape.

[Michael Schuch]

I installed a Fujitsu 1 ton in our great room 5 years ago and it kept the big room warm when it was -12 F. We were using space heaters in the bed rooms because the whole house heat pump wasn't installed very well when the house was built and doesn't keep up with heating or cooling.

At the beginning of this summer I installed a 3 zone (9000, 6000 & 6000)Mitsubishi mini split in each of the bedrooms because I like the one in the great room so much. It hasn't gotten really cold yet but I am confident the Mitsubishi will do fine when it gets REALLY cold. It did great during the 100+ F summer days.

The low temperature mini-splits are identical to the non-low temp models with the addition of a built in resistance heater in the compressor unit to keep it from freezing over. The non-low temp models will run the compressor backwards, cool inside and heat the evaporator, for a brief period of time when it needs to de-ice the evaporator. I installed the Mitsubishi compressor under a deck and 18" off the ground to keep the snow off in the winter and the dirt off in the summer.

I ran 12g THHN stranded to both the Fujitsu and the Mitsubishi with 20amp 220v breakers per the manufactures specs. The mini-splits use the same VFD technology a lot of us use for our 3 phase machines. Because the compressor can be started at very low RPM's the initial in-rush current is MUCH lower than a coventional heat pump. 100amp panel should be plenty.

I am a big fan of the minisplits and can't wait until I can afford one to put in my shop. I have seen a couple new in box mini-splits on craigslist from people who bought one and never installed it for less than half of mail order prices.

[Jeff Bartley]

I’ve been shopping a heat pump also and have seen all the HVAC direct ads. Micheal, did you install the mini splits yourself?

And Ed, your geothermal install(s) sound really enticing. I’m right up the road from you and if you’re up for a visit I’d love to have you over so you could look at my lot to tell me if you think I could fit a geothermal system here. I’ll PM my info but I’ll be over in Cedar Creek all day and out of cell range.

Zach, it sounds like you’re doing things right with respect to the renovation on your new property. I would definitely upgrade your electric service, besides the cost of the materials there’s no reason not to do it.

[Jim Becker]

If new construction, consider a larger than 200 amp panel. My son and daughter-in-law are building. Main panel, + sub in the garage for two plug-in cars (one hybrid and one tesla), plus one attached workshop (stealth gloat for my son and wife). His electrical contractor recommended a 325 amp service, then discovered it cost about the same for a 400 amp service.

With the new code for an exterior disconnect, the layout is
400 amp exterior main disconnect
200 amp sub in the mechanical room for house proper
125 amp sub in the garage
100 amp sub in the workshop

The setup I had at the old house was similar, but there's no disconnect on the outside of the house...that's not done here. 400 amp drop to the meter. Main panel in the house was 200 amps with a 100 amp sub in the addition. Feed to the shop was 200 amps directly from the meter parallel to the house with a disconnect in next to the main panel in the house and a 200 amp sub in the shop. Keep in mind, however, that the house was 4200 sq ft with two HVAC systems, etc.

That kind of thing would likely be overkill for the property that the OP is rehabbing at present, but useful for what he wants to do in the future.

[Jim Becker]

I’ve been shopping a heat pump also and have seen all the HVAC direct ads. Micheal, did you install the mini splits yourself?

There are two levels of self install...Mr Cool DIY pre-charged units can be self-installed without any kind of equipment and you get a full warranty. You can also self install many other units, but will require either obtaining the vacuum equipment you need to complete the install and willingness to eschew warranty or having the final install/setup done by a qualified HVAC technician so you can retain warranty. The first option units cost a little more for the unit, but for someone handy and willing, you get the job done without the dance required for getting a technician or figuring out the process to do things yourself.

[Brian Elfert]

The exterior disconnect switch is a new requirement with the 2020 NEC. I put in a new meter socket under the 2017 NEC last year as part of my solar project. I also added the exterior disconnect switch even though not required yet because future electrical work might trigger the requirement. I also replaced the load center in the house since it was nearly impossible to separate the grounds and neutrals with my old load center. (You have to separate the grounds and neutrals once an exterior disconnect is added. You also no longer bond at the load center.) Minnesota adopted the 202 NEC on Nov 17th, 2020 so I got in under the wire as I got my permit about a month before that.

I don't think the OP would need 320/400 amp service for his smaller house. Electricity consumption is trending down with lighting, appliances, TVs, and HVAC getting more efficient. Even if you have two electric vehicles charging at 60 amps each that leaves 80 amps remaining. Most electric vehicle charging would be late at night when electricity usage in the house is usually lower. My understanding is that 400 amp and 320 amp service are essentially the same thing.

[Jim Becker]

Good to know about the exterior disconnect, Brian...it will likely play a role when I do get to put up the new shop as one of the options for power is a separate drop from lines behind the property, rather than daisy-chaining from the house which gets fed from the street in front. I do understand about the bonding...the disconnect is "the main panel", even without space for branch circuits.

[Bill Dufour]

exterior disconnect question: I have a exterior mount main service panel on the outside of the house. It has a main disconnect inside. Does that met the new code?
Bill D.

[Brian Elfert]

exterior disconnect question: I have a exterior mount main service panel on the outside of the house. It has a main disconnect inside. Does that met the new code?


Pretty sure it will. This is mostly for us northern folk who have the service panel inside the house. The whole point of this is so the fire department can turn off the power to the house without having to go inside, or having to pull the meter. My local fire department will not pull the meter anymore due to arc flash and will wait for the power company to do it.

[Ronald Blue]

Whether it was a code requirement I don't know but when the service was installed for my new home and shop in 2018 the utility company required the meter base disconnect. I went with 400 amp service with a 200 amp panel in the shop and a 200 amp panel in the house. Transformer is set outside the shop next to the meter base. They bored the service entrance cable in. As I recall each has it's own disconnect.

[Jim Becker]

The requirement for an external disconnect in the new NEC makes sense to me for good reasons, including what Brian just mentioned...increased safety in emergencies.

[Zachary Hoyt]

The external disconnect does seem like a good idea. I don't know if the town where I'm going has adopted the 2020 standard, or if it's done at a state or county level. I am still waiting for a response from National Grid about the wire to the meter, and I need to contact a local electrician up there to find out about availability and cost for various jobs.

[Jim Becker]

You could just ask the licensed electrician that will install your service to do the external disconnect, even if the local jurisdiction hasn't moved to the newer code, although they could certainly object (unlikely) to it during the permitting process. You or the electrician can ascertain that likelihood with a call to the local building code office. That's how I made sure my permit for the sub in my temporary shop got approved first time...I discussed the plan before submitting the "digital paperwork".

[Brian Elfert]

As best as I can find New York State is still on NEC 2017, but I would verify with your city or county.

I don't know any reason you couldn't add the exterior disconnect switch under the 2017 NEC. I installed mine under the 2017 NEC. People have been adding disconnect switches like this for a variety of reasons under older versions of the NEC.

[Jim Becker]

Brian, the only reason I could think that it might be an issue is "local personality", if you catch my drift. But that's why I suggested that Zachary touch bases with the jurisdiction early.

[Ronald Blue]

The irony in the meter base disconnect is that for as long as can remember the meter base on the farm had a disconnect on it and that would have been in the 60's initially and then when an upgrade required for grain handling equipment the heavier service also did. Code wasn't a factor at all but that was standard on Rural Electric at least in that coop.

[Brian Elfert]

The irony in the meter base disconnect is that for as long as can remember the meter base on the farm had a disconnect on it and that would have been in the 60's initially and then when an upgrade required for grain handling equipment the heavier service also did. Code wasn't a factor at all but that was standard on Rural Electric at least in that coop.

Are you sure that wasn't a bypass on the meter base, which isn't a disconnect? A bypass allows the electric company to replace the meter without interrupting power. Many utility companies require them these days for new meter bases.

[Ronald Blue]

Definitely not. They were main breakers that killed all power.