240 split phase vs 230v European inverter and US split phase devices

[Hedges]

Single pole contactor might serve to turn it on and off, and might be rated for the voltage. I prefer no hot wires when off. But contactor is remote controlled, could come on any time so up to you to protect yourself.

The circuit should be protected by double pole if fed 240V split-phase.
You could have 240V single ended circuit if the breaker is rated for it. If you put 230V L-N in a Square D breaker panel and use a single pole breaker, most aren't good for more than 120V. Some are (for 277V circuit), and the 3-pole ones are.
DIN rail breakers, many are rated for 230V or 277V. Some of the Midnight have a 120/240V sticker on them, but CBI sticker underneath corresponds to 277V, if I remember correctly.

 

[CoolWill]

There are many 240vac air conditioners that use single pole contactors. That should not be allowed.

Why?

 

[timselectric]

There are many 240vac air conditioners that use single pole contactors. That should not be allowed.

Agree 100%
If something is off, it should be all of the way off. (Not halfway off)
All ungrounded conductors should be disconnected from it.

 

[SparkyJJO]

There's a reason why a 2 pole equipment disconnect is required at the outside condenser.

 

[FilterGuy]

There are many 240vac air conditioners that use single pole contactors. That should not be allowed.

That should not be allowed *in North America with split-phase systems*.

In the EU, a single pole switch on 230 is fine because the other leg is neutral.

 

[timselectric]

I assume that these (single pole contactor) models are sold internationally.

 

[timselectric]

That should not be allowed *in North America with split-phase systems*.

Yup
It would be similar to using a two pole starter for a 3-phase motor.
While the motor wouldn't be running.
All conductors are still live.

 

[FilterGuy]

As @Hedges said, a single pole works fine for controlling on-off. I don't know what code says, but if the contactor is down deep in the unit, it might not be required because it is not a disconnect, it is a control. If someone is mucking around down deep in the unit while power is applied, they damn well better know what they are doing.

 

[Hedges]

(L1 and L2)

I think some thermostats and over-temperature switches only open one leg. Same issue.

https://www.lowes.com/pd/EASTMAN-Water-Heater-Thermostat/1002871486

Over Temperature Switch 195’F – Heat Shrink Equipment

heatshrinkequipment.com

So long as a screwdriver is required to access the hazardous unswitched circuits?

 

[timselectric]

NEC doesn't apply to equipment internally.
Only the external connections to it.

 

[FilterGuy]

NEC doesn't apply to equipment internally.
Only the external connections to it.

That is what I thought...... NEC will require a double pole disconnect of the piece of equipment but will typically cover the 'guts' of the equipment by simply saying it must be listed. Unless the associated UL requirements demand a double pole, the company is not going to put one in.

 

[timselectric]

That is what I thought...... NEC will require a double pole disconnect of the piece of equipment but will typically cover the 'guts' of the equipment by simply saying it must be listed. Unless the associated UL requirements demand a double pole, the company is not going to put one in.

Right
And sometimes things slip through the cracks.
I don't know what UL requires in this situation. But I don't like the idea of any type of "switch" , in the off position. Having all terminals live.
It complicates troubleshooting faulty equipment.
It can still be done. You just have to change your mindset and use different testing procedures.

 

[FilterGuy]

Right
And sometimes things slip through the cracks.
I don't know what UL requires in this situation. But I don't like the idea of any type of "switch" , in the off position. Having all terminals live.
It complicates troubleshooting faulty equipment.
It can still be done. You just have to change your mindset and use different testing procedures.

I don't have a lot of insight into UL standards but my impression is that they look primarily at whether an item is safe to use. Not necessarily if it is safe to service. However, a *lot* of the NEC requirements are there for safely servicing systems.

 

[timselectric]

All of the NEC is designed for safety of people, and property.

 

[1201]

SO.... you could make a 230V EU inverter work on a 240V US load, but you must be extremely careful to understand what is happening with grounding and bonding so you don't end up with energized metal surfaces or dead shorts. Furthermore, once you get it working it would be such an odd set-up, it is just begging for someone to do something that will be dangerous.

I could probably draw something up that would work, but I am so against doing it I won't assist others by showing how.

So pretty much the only simple and safe way to use the grid with a 230v inverter and only 240v loads is to use a separate on grid charger to keep the battery charged and have the inverter just always draw from solar and battery?

 

[timselectric]

So pretty much the only simple and safe way to use the grid with a 230v inverter and only 240v loads is to use a separate on grid charger to keep the battery charged and have the inverter just always draw from solar and battery?

Just don't pass the grid through the AIO.
The loads can be transferred between the two, after the AIO, safely.
This is how I designed my system.

 

[FilterGuy]

So pretty much the only simple and safe way to use the grid with a 230v inverter and only 240v loads is to use a separate on grid charger to keep the battery charged and have the inverter just always draw from solar and battery?

Simple and safe are a bit subjective, but that would probably be the safest way to do it..... but even then, the inverter might have a dynamic bond meaning one leg of the 240V is tied to the ground. This is not 'unsafe' by itself, but it is enough out of the norm in the US that it is just begging for someone to misunderstand and do something dangerous.

If the inverter does not do bonding, then the circuit is floating and a breaker won't clear a ground fault.

You can make it work, but it's the corner cases that will get you. If you follow the standards for the US, the fault scenarios have been thought through. When you do mix of standards like this, it is incumbent on you to make sure you have thought through all the fault scenarios, and that is very hard to do with confidence. Are you sure you thought of everything?

 

[timselectric]

When you choose to use something in a way that it was not designed for. You become the engineer of the finished product. Definitely make sure that you cover all possible scenarios. With safety at the top of the list.

 

[FilterGuy]

When you choose to use something in a way that it was not designed for. You become the engineer of the finished product. Definitely make sure that you cover all possible scenarios. With safety at the top of the list.

And that is exactly why I can't recommend doing this. I have a good handle on how it all works and I can spot many of the potential problems, but I can't be sure I can spot all of the problems....so it is not worth it to me.

 

[CoolWill]

The only single pole contactors used on 240 volt equipment are inside it. The compressor and fan are often turned on and off by opening a single pole. It is not a disconnect. It isn't designed to be. There is is nothing odd about it and has been done that way for a long time. The NEC has no say on internal equipment.

There is also at least one example I can think of in the code that also allows only one pole to be opened. 3 way switching of some 240 volt equipment is allowed by opening one pole.