OT (semi) - can 240v single phase outlets be daisy chained?

Title pretty much says it - I've done lots of 120v writing, but the only 240v I've done was from the breaker to a single socket. Now I need another socket further down the wall; can I just daisy chain from the first?

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you have 240 v ? in the USA obviously is it common in the home?

it still would be 60 hz ?

Just thinking out aloud if i can run my single phase 240 v 50 hz tools in the USA.

awake said:

Title pretty much says it - I've done lots of 120v writing, but the only 240v I've done was from the breaker to a single socket. Now I need another socket further down the wall; can I just daisy chain from the first?

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yes, but it's real easy to overload a circuit.

Shouldn't be a problem, as long as only one machine is running at a time. I have a 220 line that goes to the table saw, the lathe with a static convertor, and the mill with a VFD. But it's just me down there.

DISCLAIMER: I am a cabinetmaker, not an electrician. And I did not stay at a Holiday Inn last night.

Daisy chain is not mentioned in the code.

Parallel is usual and customary.

Tell us what you should concern yourself with.

Street said:

you have 240 v ? in the USA obviously is it common in the home?

it still would be 60 hz ?

Just thinking out aloud if i can run my single phase 240 v 50 hz tools in the USA.

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Yes, nearly every home in the U.S. that has electricity has 240VAC 60Hz single phase. It's not very common to have extra outlets besides what it's used for though (usually AC, possibly an electric range and/or electric clothes dryer) unless you're people like us.

awake said:

Title pretty much says it - I've done lots of 120v writing, but the only 240v I've done was from the breaker to a single socket. Now I need another socket further down the wall; can I just daisy chain from the first?

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YES!

I've run my lab as three wire, with every other outlet a 240V. That's along 36" of exterior wall with either a split duplex 110 outlet or a single 220 v outlet every four feet..

It works great!

As long as you have the proper fuse/breaker,no problem

That's pretty much how the rest of the planet that uses 220-240 Volts works. The main thing to watch out for is that there is a breaker at the power supply end that limits the current to a suitable amount. There will be an upper limit on how many outlets per cable can be used depending on local rules. Cable should be appropriately sized for the current used and a 2 pole earth leakage/circuit breaker combo is a good idea, with a C curve or if using a welder a D curve type breaker.

I like CalG's scheme. I did something similar when I built my shop in Florida. I ran 230 V to every outlet, even if I only installed 115 V outlets. I figured I could always change the outlets later if I found I needed 230 V.

As far as chaining them, yes you can. But consider this. In the US, the 115 V 15 A and 20 A outlets are the general purpose outlets and they are used wherever you need any amperage less than 15 or 20 Amps. And most, dare I say 99.99% of all electrical devices that use 115 V are less than 15 Amps, usually less than 10 or even 5 Amps. This gives us a false sense of universality. When you go beyond that 15 or 20 Amp point and beyond 115 V, then things get a bit more specific. There are a number of outlets that are for specific Voltages and Currents. For instance the standard dryer outlet is 230 V and 30 Amps. It will be run on wire that is capable of handling 30 Amps and the breaker will be a 30 Amp. breaker. Now the dryer will draw around 25 to 30 Amps. so that circuit will be maxed out with very little, if anything, to spare.

All higher Voltage and higher current circuits are run in this manner. They are sized for a specific Voltage and current to match the device they were installed for. The plug and outlet will have a specific configuration of the pins that is unique to that Voltage AND current. There are dozens of different three and four prong plugs and outlets, each for a specific Voltage and current combination. This is deliberate so that no one plugs in a device that draws more current or that expects a different Voltage in that outlet.

The consequence of this situation is that most 230 V circuits will be maxed out. If you chain another 230 V outlet on an existing circuit and run two devices at the same time, you will very likely blow the fuse or breaker. Even adding a 5 amp., 230 Volt device (motor?) to an existing dryer circuit will be taking a chance on exceeding the breaker's rating. It may not blow right away, but after a few minutes, POP!

So, chain outlets? Yes you can. But it could cause problems and you need to be very sure about what you are doing. One thing I have considered doing is to install what is basically an extension cord that runs through the wall or at least through installed conduit. When I need 230 V at a different location, the machine at the first location is unplugged and the extension circuit would be plugged in. I am not sure how that would square with the NEC. But it does sound like a safe way to do it.

One thing you definitely do not want to do is to replace an existing breaker or fuse with a bigger one without being absolutely sure that the wire going from that breaker to the outlets is large enough for that new breaker or fuse. That would definitely be a fire hazard.

Thats good to know i thought you ran on 110V 60 hz mostly.


Over here we run 240V plugs for pretty much everything, you do have the option depending on the Street power pole to have 3 phase connected then you can run 3 phase aircon, 3 phase stove.
Most stoves have the option to be in single or 3 phase.
3 phase is regarded as being more efficient for higher power devices its higher voltage as well as higher current and cheaper to run devices. ( 415 Volts )

You'll need wire enough to handle all the outlets in the line. Breaker for the wire, not the machinery. If you want to run four 50amp outlets in parallel, have at it.... but you'll need 200 amps worth of wire and breaker.

Street said:

Thats good to know i thought you ran on 110V 60 hz mostly.

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They do. You need to keep in mind that, AFAIK, their 240V is the same as our (usually rural) 480V - 2 active conductors. I'm not an electrician so can't say if our tools would work on a US 240V circuit but I kind of doubt it. Most tools are cheap enough that it's not worth the hassle of transporting them anyway.

PDW

Mike C. said:

You'll need wire enough to handle all the outlets in the line. Breaker for the wire, not the machinery. If you want to run four 50amp outlets in parallel, have at it.... but you'll need 200 amps worth of wire and breaker.

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Sorry, no.. I think what you meant to say was that you'll need ONE 50A breaker for the whole chain.

"Parallel" IS the distribution being referred to as 'daisy chain'. The outlets are for-sure not in series, and "weakest link" and all still applies, even if they were.

If you 'home run' each outlet - but ONE outlet on each branch - then one 50 A breaker per-each back at the load center.

The load center 'main' breaker may need to be 200A - or more.

PDW said:

They do. You need to keep in mind that, AFAIK, their 240V is the same as our (usually rural) 480V - 2 active conductors. I'm not an electrician so can't say if our tools would work on a US 240V circuit but I kind of doubt it. Most tools are cheap enough that it's not worth the hassle of transporting them anyway.

PDW

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The main thing to keep in mind is simple enough. US (and Japan) are centre-tapped to Neutral/Earth last-leg systems. Sometimes called 'split phase' flavour of single-phase.

Most of the rest of the world may see 230 V to 250 V 'above ground', and nothing less.

We see only 110-130 V above ground, parts of Japan only 100 V above ground.

US/Japan nominal "across the legs" 200 to 245 or so is ALWAYS there. There are no 120 V-only utility company delivery, nor even common off portable gen sets.

We still have the same 2XX power available as the rest of the world, and universally [1]. Usually off higher power service entrances as well.

A 200A service was pretty basic for even a modest dwelling built 40 years ago, 300A not uncommon for many years now for larger homes. And we have a LOT of those, some areas.

It is just intended to reduce shock-hazard for what is waaay more common - the 120 we 'attempt' to balance, either side of the line for residential & office use.

[1] The b****y annoying nattering and whining of hobbyists that they "only have 120 V" is merely poverty or laziness at not running a branch back to where the 220-240 V exists. It IS THERE. Moreover, any Hong Kong, other Asian, UK/European, or Oz sourced appliances, cookers, or power tools - and we have such in our home, 25 years and more - have always run just fine off it. The 50 Hz to 60 Hz is largely a non-issue.

Thats good to hear one tool here one tool there and they soon add up to alot of money in tools.
especially some of the electric over hydraulic Rehau tools.

So would i be correct in saying you have a different plug for the 240v side, just so no one plugs in 110v appliance to it?

What does it look like?

Street said:

Thats good to hear one tool here one tool there and they soon add up to alot of money in tools.
especially some of the electric over hydraulic Rehau tools.

So would i be correct in saying you have a different plug for the 240v side, just so no one plugs in 110v appliance to it?

What does it look like?

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Nema 6-15 or 6-20 is "correct", it is on many high capacity window air conditioners but.....

There is no reason I know of that obligates a twist-lock to be locked-in, and/or both voltages drawn from a 125/250 twist-lock plug.


I recently installed a 125/250 twist-lock for a custom extension cord to supply two duplex outlets (each on its own breaker). The VFD-driven bandsaw has the same twist-lock plug, but the center tap "neutral" blade of the plug is connected to nothing.

I suspect some would extract or cut off that blade; I'm happy to ignore it.

The breaker is a common trip two pole breaker.

For most hand-portable tools the 50/60 issue just DOES NOT exist, since most of them are "universal" motors that care little about the frequency since they are a series AC/DC motor. ** They will run at the same speed with 50Hz or 60Hz. All they need is the voltage.

The 240V outlet deal, there is no inherent reason why you cannot have more outlets than one on a 240V circuit. It is not COMMON in the US because most 240V items are large enough that they do get their own circuit.... Dryers and stoves typically need higher currents, and portable cord-type tools are not capable of dealing with the possible fault currents. You do not want the fault current that a 50A breaker allows to flow though a portable tool cord.

But for 15A and 20A circuits, regular plug-in devices rated for the voltage are reckoned to be capable of opening the breaker if there is a fault. And, remember, a 15A 220 circuit is the power equivalent of a 30A 120V circuit, so it is not as limited on how many items can be plugged-in and used. Any given device pulls half the current at 240V that it would at 120V..

As for mixing 120V and 240V outlets on one "multi-wire branch circuit" (2 hots and neutral pulled, with 120V outlets alternating to each hot), I'd have to look that up. I have not run into that, never considered it, so I am not sure what the code says, but as a "reflex" I would likely not do it.

For plugs, thre seem like a lot, but in general fewer get used than are possible. And it is allowable to use any type that is rated for the voltage and current. The restriction is that you (naturally) may not use one type for different voltages.

The 120V plug is just for that, but a 240V plug could be used at 120V, if desired for some reason, such as to restrict a machine from being plugged into a 15A circuit that uses a NEMA 5-15 outlet. Then, you would have to NOT use that plug type for any other use in the building. There IS a 20A 120V plug (NEMA 5-20 per the chart posted), but the compatible outlets set up for either that or 15A tend to get used everywhere, so that is not a good option for restriction to 20A circuits.

** In fact, the DC compatibility is ancient, a sort of "extra" these days, when DC is nearly extinct. The motors are really designed to work with AC (low inductance, etc) but no inherent reason why DC would not work if you had it.

CalG said:

YES!

I've run my lab as three wire, with every other outlet a 240V. That's along 36" of exterior wall with either a split duplex 110 outlet or a single 220 v outlet every four feet..

It works great!

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Yes it does. NEC refers to it as "multi-wire"; requiring two-pole breakers, and grouping the conductors (in the panel) to avoid future confusion.

21.4(D) Multiwire Branch Circuits. Grouping.

You cannot daisychain the neutral wire; it must be pigtailed at each device (when using multiwire).


Branch Circuit Requirements and the NEC - Part 1

https://www.mikeholt.com/mojonewsar...ngDangersMultiwireBranchCircuits~20020218.htm