440 Volts?

I’m looking at a home listing with “Electric information: 440 Volts.”

What exactly will this mean for a residence? I’m not likely to ever run a welder. But an EV charger could happen in the future. This is a positive, not a negative, right?

This is a positive, not a negative, right?

Yes, unless it’s the only voltage available, in which case you need new refrigerators, lightbulbs, fans, TVs, radios, toaster oven, coffee maker, computers, and, well, everything :wink:

Odd that 440vac is available at a residence… 240vac is normal, but 440vac may even be a 3 phase setup, also not normally in a residential area… But be warned, that 440v is deadly, not to be toyed with 120/240 can hurt you, but 440 kills, goes internal, not just surface injuries…

Co-worker, dropped a socket below an open panel, his head hit the busbar as he leaned to pick it up, ended him. Lost a couple electricians overseas, too, drilled into a 440 conduit buried in the concrete wall… Some accidents are memorable… Others, get your attention, hurt a bit, but survivable…

Sometimes a real, licensed, electrician is called for…

4 Likes

The first thing that comes to my mind is a typo.

–Peter

4 Likes

Most likely erroneous information in the listing if this is a normal residence. I can only see having 440 if it’s zoned for mixed/industrial, and the owner has something like a heavy duty wood shop or machine shop in a building on the property. You won’t find residential appliances for 3 phase 440v service.

2 Likes

That would be my guess also, but I would want to confirm.

I’m pretty sure that in my area, ONLY 240V is available for residential. That comes into the house, and then they separate it into 120V for most applications (i.e. outlets). I suppose different areas may be different, and as another poster said the neighborhood may have been zoned for other than residential at one point.

But I suspect a typo until proven otherwise.

Also, isn’t it 120V, 240V, and 480V? And 480V is three-phase, right? I didn’t know there was a 440V option.

But if you have a step down transformer to your 240v service line (as all of us do) you probably do have 440v on the closest telephone pole. Bringing it inside to an fast EV charger requires some wiring but not long distances.

I don’t know where they step it down. We have no “telephone poles” in our area. The only thing sticking out of the ground in the neighborhood is the telecom panel (it’s about the size of a fire hydrant). But, yes, they do have to step it down near the neighborhood. Somewhere.

I just never heard of them NOT stepping it down for the last mile. I didn’t think you had a choice. Only a 240V gets wired to the house, and then it’s split to 120V there (unless you have a 240V outlet, which we do…and our EV charger is connected to it).

1poorguy

In my neighborhood the service lines are buried but we do have a few transformer boxes around as well as cable and telephone connection boxes.

440 might require building code adjustments etc. But if fast ev charging becomes popular, those adjustments can be made.

you probably do have 440v on the closest telephone pole.

I have underground service, and the transformer is a couple houses away. But I’m pretty sure it’s not 440V. It might be 480V/277V 3-phase.

Bringing it inside to an fast EV charger requires some wiring but not long distances.

I don’t know of any EVSE units that use 440VAC or 480VAC and are reasonable to put into a home.
There are 440V DC fast chargers - those are quite expensive ($15k+ vs. less than $1k for a 240V level2 charger)

My bet would be on it being a typo - someone typed ‘440’ instead of ‘240’.
If it were 3-phase 480V/277V, I think it’d be listed as 480V or 480/277V (but that’d be really unusual for a residence.)
Even the more common 3-phase of 120/208 is still fairly unusual for residential (but often seen in commercial business settings)

Jeff Brig: “Most likely erroneous information in the listing if this is a normal residence. I can only see having 440 if it’s zoned for mixed/industrial, and the owner has something like a heavy duty wood shop or machine shop in a building on the property. You won’t find residential appliances for 3 phase 440v service.”

Are there lower voltage three-phase service that is (or formerly was) not uncommon for an older residential area?

Regards, JAFO

I tried googling this.

https://www.google.com/search?client=firefox-b-1-d&sxsrf…

One explanation that mentions 440V and tries to actually make sense of it:

https://instrumentationtools.com/why-three-phase-voltage-is-…

A couple machinist friends, one in town, the other in the rural area would love to have 440 3Phase available, the’ve both bought surplus Monarch 10EE machinist lathes when Mare Island Naval Shipyard in Vallejo, CA, closed down, and it would have made their lives simpler… Instead they had to buy a converter, or use a couple 3Ph motors to create the 3 Ph it takes to spin the beautiful lathes into action… Last I heard, one had his going, not the other, so far…

It took a tow truck, big one and removing the wall of his shop to bring the nearby fellows buy home… He already has a nice big Bridgeport Mill in there, along with another big lathe, so 3 phase would be really handy. 3 Phase 5 & 10 HP motors can be bought pretty cheap, if one can use them…

Heavy tools can do some serious work… Ages ago, he turned, from big blocks of steel, replacement cylinders for his Harley project bike, fins and all… He once held the land speed record for normally aspirated (carbureted) Harleys, I think it was over 90 cu in… Vroom! But when injected, prebuilt V-twins came along, he lost interest… For times for a while…

Are there lower voltage three-phase service that is (or formerly was) not uncommon for an older residential area?

3-phase 120/208 is fairly common in commercial buildings.
I think there are some farms (and farmhouses) that have it. And maybe some condos/apartments.
If you had 3-phase to a house, I think that’s the one you’d most likely have.
But even that I think is uncommon.

https://ctlsys.com/support/electrical_service_types_and_volt…
has some nice diagrams showing voltages between wires for common electrical services.

2 Likes

Three phase is most useful for motors and heavy equipment. Commercial building might need it for AC compressors. Farms most often for irrigation pumps.

Three phase fills in the gaps between the 60 hz sine waves on three wires. Carries more power for a given size of wire. If rectified for an ev charger should save on wire size.

So it looks like what we’re, or at least myself, has been calling 440, must be 480 3Ph…

I don’t see the 277vac breakout in the article, tho… We used it for all the lighting in Telco Central Offices, at least the larger ones… it, was a nasty hit if one slipped up…

Ahh, now I see the 277vac in the chart… Oops…

3-Phase, 4-Wire 480Y/277 V 277 480 US

Farms most often for irrigation pumps.
I think on my grandparent’s farm the compressor was the big user of electricity. It’d be running for many hours each day, cooling the milk down and keeping it cold. There were other electric motors, like the barn cleaner, the feed grinder, the hay elevator, the silo unloader. But those were run only for short times and probably not as many HP.

The irrigation pump on a nearby farm to where I grew up wasn’t electrical - it was driven by a gas (or maybe diesel) engine. That was a good-sized pump/engine - probably more horsepower than you’d get from an electric pump without spending a lot of money.
It pumped the water out to a center-pivot irrigation system.
The wheels for the center-pivot were electrically driven IIRC.

Three phase is most useful for motors and heavy equipment. Commercial building might need it for AC compressors.
AC compressors (and the air handlers to go with them) would probably be the most likely things to have 3-phase.
But if there’s machinery, those might have 3-phase motors too.
Things like refrigerators, office equipment, etc. would likely be 120V. Things that’d be 240VAC in a residence would probably be 208V

Most floor mounted tools, jointers, planers, table saws, bandsaws run better, start easier on 220, so when I built my shop, every other outlet on the outer walls are 220vac, with 120vac in between, I used yellow covers on the 220 outlet, blue for the 120’s, plus they are a different, outlet… Radial apr, jointer are on the 220, but I didn’t run 220 to the floor outlets for the table saw & workbench… But all are single phase… lighting is all 120vac… residential has its limits…

Our house in Pittsburgh had 440 volts in the basement, which was the previous owner’s machine shop. He got rich inventing a valve for an artificial heart in the basement - the next door neighbor was a heart surgeon! But that’s the only place I’ve ever lived that had that kind of voltage. But then he had industrial lathes and stuff, so I guess he needed it?

At our current house, however, we have 7200v in a transformer box at the corner of the lot, or so the sticker on it says. Coming into the house is 220, of course. Our utilities are underground, I don’t know if that has anything to do with why there’s such high current in the box.

We had to replace a water line and the guy using a ditch witch was extremely careful to give the pad mounted transformer box a wide berth. That sticker got its message across very well.

2 Likes