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Live Ground Shocked 5 Year Old

Hedges said:
Breaker - be aware that if N is bonded to ground, L is 240V and many breakers aren't rated for that. e.g. 120/240V QO breakers are for the most part only 120V per pole. Only select ones are 240V or 277V rated. I think the Midnight CBI and Carling breakers, at least some, are 240V rated (even if not advertised that way; look up manufacturer's model number.)

If you want an auto-transformer for split-phase, you can use primary 240/480V windings of a typical transformer at 120/240V and be able to get 100% of inverter rating on either L1/L2.
Click to expand...
good call on the breaker! this will strictly be a dedicated inverter to heat water, so no concerns about transformers. inverter was a mistake purchase, it was advertised in a way that made it seem to do 220/230/240 well it can but not in split phase so its been a boat anchor for the last 18 months... I got tired of seeing full batteries on a 70kw of battery at 1100 in the winter so why not run an electric water boiler/heater and raise these stakes a bit?
 
Hedges said:
Breaker - be aware that if N is bonded to ground, L is 240V and many breakers aren't rated for that. e.g. 120/240V QO breakers are for the most part only 120V per pole.
Click to expand...
Where did you get this information?
They are rated for 240v.
A two pole breaker on a split-phase panel is flowing 240v and will have no problem tripping at 240v. They must be able to trip a line to line (240v) dead short. Same goes for single pole breakers on multi wire branch circuits.

Screenshot_20240408_213910_Chrome.jpg
 
timselectric said:
Where did you get this information?
They are rated for 240v.
A two pole breaker on a split-phase panel is flowing 240v and will have no problem tripping at 240v. They must be able to trip a line to line (240v) dead short. Same goes for single pole breakers on multi wire branch circuits.

View attachment 208083
Click to expand...
so Tim, excuse my ignorance on this subject.

If a two pole breaker is designed to have 240 split phase then in reality each pole would carry 120 correct. if this is so then can I use a three pole 240 3phase breaker and just interrupt all three lines? (L1, neutral and ground)?
 
Daddy Tanuki said:
If a two pole breaker is designed to have 240 split phase then in reality each pole would carry 120 correct. if this is so then can I use a three pole 240 3phase breaker and just interrupt all three lines? (L1, neutral and ground)?
Click to expand...
Neutral and ground are not normally switched on a breaker. A three pole breaker switches L1, L2, and L3, all hot legs.
Switching ground is of course particularly dangerous.
 
ricardocello said:
Neutral and ground are not normally switched on a breaker. A three pole breaker switches L1, L2, and L3, all hot legs.
Switching ground is of course particularly dangerous.
Click to expand...
What about in a transfer switch? In my setup using a Growatt SPF 12k which has in internal autotransformer, the grid input has two legs, connected to L1 and L2. The unit has one neutral which I have tied to a common neutral in the sub panel according to Ian’s diagrams on Watts 247. I have a two pole transfer switch to power the Growatt in bypass mode from a generator instead of the grid. From the generator, L1 and L2 go through the transfer switch. The generators neutral is connected to the same common neutral in the sub panel and the generator ground is connected to the separate common ground. Neutral and ground are not bonded in the generator or sub panel, only in the main panel.

Should I also be switching the neutral from the sub panel to the main panel so when the generator is connected, the neutral is removed from the main panel and connected only to the generator? Or does it even matter?
 
ricardocello said:
Neutral and ground are not normally switched on a breaker. A three pole breaker switches L1, L2, and L3, all hot legs.
Switching ground is of course particularly dangerous.
Click to expand...
so then use one leg of it to switch only L1 is that acceptable? or would be switching L1 and neutral but not the ground be the best?

Reason I ask is I have several 3 phase breakers of varying amperage I picked up used from a recycle shop for pennies. European style 230 single phase is not something I have ever used (or studied or looked into). here in japan its split phase 200 so L1 100 volts, L2 100 volts and neutral.
 
Daddy Tanuki said:
so Tim, excuse my ignorance on this subject.

If a two pole breaker is designed to have 240 split phase then in reality each pole would carry 120 correct. if this is so then can I use a three pole 240 3phase breaker and just interrupt all three lines? (L1, neutral and ground)?
Click to expand...
Each pole is carrying 240v, on a 240v load. And 120v, on a 120v load.
Neutral is not usually switched. And ground should never be switched.
In this specific situation I would use a MCB in its own enclosure. Either a 1 pole for L1 or a 2 pole for both L1 and N (Personal preference).
Grounding should connect to your existing Grounding system.
 
timselectric said:
Each pole is carrying 240v, on a 240v load. And 120v, on a 120v load.
Neutral is not usually switched. And ground should never be switched.
In this specific situation I would use a MCB in its own enclosure. Either a 1 pole for L1 or a 2 pole for both L1 and N (Personal preference).
Grounding should connect to your existing Grounding system.
Click to expand...
thanks!
 
Brett V said:
Should I also be switching the neutral from the sub panel to the main panel so when the generator is connected, the neutral is removed from the main panel and connected only to the generator? Or does it even matter?
Click to expand...
No, and it does matter.
The common neutral is providing the N/G bond for all parts and modes of operation.
 
I have two rules for split-phase neutrals:

1 No Floating Neutrals
The 120V loads in a split-phase panel SHALL have a neutral that connects to the source of power at all times.
Violation Penalty: All of your 120V loads could see voltages anywhere from 0 to 240V depending on their resistance.
Smoke, $$$$
Example: Forgetting or failing to connect the incoming neutral in a subpanel.

2 One Neutral-Ground Bond
The ground conductors exist to handle faults. If you have multiple N-G bonds, there are parallel ways the fault current can travel.
Stick with one N-G bond, preferably in the main panel.
Violation Penalty: Faults might not clear correctly.
There may be objectional current flowing on the ground lines between the two (or more) N-G bonds.
Example: Generator has ground bond to neutral, inlet to transfer switch/lockout creates a ground loop.

You might get away with violating #2 and not necessarily notice, but don’t ever try that with #1.
 
timselectric said:
Where did you get this information?
They are rated for 240v.
A two pole breaker on a split-phase panel is flowing 240v and will have no problem tripping at 240v. They must be able to trip a line to line (240v) dead short. Same goes for single pole breakers on multi wire branch circuits.
Click to expand...

Somewhere I read it explicitly, I thought. Where it is clear but doesn't jump out at you is selection guide and data sheeting saying "240V", not just "120/240V" and "120V", for select models but not others.

In the QO family, all the 3-pole breakers are rated higher per pole, (277V I had thought, not finding now) but definitely 240V per pole.
Select 1-pole and 2-pole breakers of a different model number (contains "V", I think"H") are also rated 277V.
Garden variety QO breakers are only 120V per pole. A 2-pole breaker rated 120/240V is only for individual Ln of 120V. L1 & L2 can be 240V apart, but handles are ganged to trip together so 2 poles in series interrupt 240V.


"What is the maximum allowable ampere and voltage rating of a QO circuit breaker that can be installed"

1712671588688.png

But that gives breaker panel model line, and mentions maximum voltage rating of breakers but doesn't say all breakers have that voltage rating.

It is very hard to find the info on their website. The following data sheet for QO130 says "120/240V" and "120V". Somewhere we will find this means it can be used in a split-phase 120/240V system, NOT in a 240V single-phase system or as one pole of a 240/480V circuit (do those exist?) and not 277/480Y (of course not, doesn't say 277V). But not for a 240/416Y system, anyway. Where it would see 240V across one pole.



Big confusion there that Schneider says "120/240V" for the single pole breaker. Not meaning it can work at 240V, just that it can be used in a 120/240V system where no line voltage exceeds 120V.

Note QO230 is rated "120/240V" and "120V"

www.se.com

QO230 - Mini circuit breaker, QO, 30A, 2 pole, 120/240VAC, 10kA, plug in | Schneider Electric USA

Schneider Electric USA. QO230 - Mini circuit breaker, QO, 30A, 2 pole, 120/240VAC, 10kA, plug in.
www.se.com www.se.com


Note difference QO230H. It is rated "120/240V", "240V", and "120V".

QO230H - Mini circuit breaker, QO, 30A, 2 pole, 120/240VAC, 10kA, plug in | Schneider Electric USA

Schneider Electric USA. QO230H - Mini circuit breaker, QO, 30A, 2 pole, 120/240VAC, 10kA, plug in.
www.se.com www.se.com


Same difference for QO330 (doesn't say "H"). It is rated "120/240V", "240V", and "120V". Doesn't say 208V, but I think it is fine in 120/208Y. Not in 240/416Y.

www.se.com

QO330 - Mini circuit breaker, QO, 30A, 3 pole, 120/240VAC, 10kA, plug in | Schneider Electric USA

Schneider Electric USA. QO330 - Mini circuit breaker, QO, 30A, 3 pole, 120/240VAC, 10kA, plug in.
www.se.com www.se.com


I thought QO panels worked for 277/480, but I'm not finding any QO series 277V, only E-frame bolt on.

Here's one note explicitly mentioning "QO__H" series breakers fully rated 240V, not 120/240V rated breakers, for 3-wire 240V delta.
(That would be a corner grounded delta in a breaker panel with one N and L1, L2, correct? Maybe not - I find 3-phase QO panel boards that say 240 delta, but the ones I've seen with 2 not 3 plug-on busbars only say 120/240V. Strange I can't find anything higher than 120/208Y or 240 delta, when some breakers are rated 240V per pole.)


"

Can an NQ panel be used on a 240V 3PH Delta system ?​

Issue:
NQ panelboards rated for a 240V 3 phase 3 wire delta voltage system

Product Line:
Panelboards

Environment:
NQ

Resolution:
Yes. Branch breakers must be 3P or QO--H / QOB--H and must carry a full 240V rating.
NOTE: This is not the same as a 240D/120VAC 3PH 4W system.
https://download.schneider-electric...17.1434407716.1686064075-258592155.1681310191"

Daddy Tanuki said:
so then use one leg of it to switch only L1 is that acceptable? or would be switching L1 and neutral but not the ground be the best?

Reason I ask is I have several 3 phase breakers of varying amperage I picked up used from a recycle shop for pennies. European style 230 single phase is not something I have ever used (or studied or looked into). here in japan its split phase 200 so L1 100 volts, L2 100 volts and neutral.
Click to expand...

If one side of inverter (N) is bonded to ground, then only hot L1 has to be switched. The 3 pole QO breakers are all rated at least 240V per pole.
Otherwise, use a QO___H breaker. That's of QO series. Various brand DIN rail including Schneider Multi-9 are rated 277V.


Hey, here's a shunt trip! This could be used with thermostat to cut power to a panel with auto-transformer if transformer overheats.

QO2301021 - Mini circuit breaker, QO, 30A, 2 pole, 120/240VAC, 10kA, plug in, AC shunt | Schneider Electric USA

Schneider Electric USA. QO2301021 - Mini circuit breaker, QO, 30A, 2 pole, 120/240VAC, 10kA, plug in, AC shunt.
www.se.com www.se.com
 
In simple terms.
AC electrical equipment is rated in voltage levels.
250v
600v
1000v
And so on.

In North America
120v, 208v, and 240v systems utilize the 250v rated equipment.
277v and 480v systems utilize the 600v rated equipment.

The number of poles a breaker has doesn't change its individual pole rating.
Poles are tied together with a common handle, so that all ungrounded conductors of a circuit are operated together. (On or off)
When a multiple pole breaker trips. A single pole trips and the handle turs off the remaining poles.
This is one of the reasons I prefer breakers over fused disconnects.
If a fuse blows in a multiple pole disconnect. The remaining ungrounded conductors remain live. Until someone physically turns the disconnect off.
 
Although breakers for 277/480V aren't rated 600V, couldn't be expected to successfully interrupt a 600V circuit.

When 120/240V circuit has fuses, each fuse has to to be good for 240V, because likely only one blows when feeding a 240V heating element load. Fault to chassis would be 120V, and fault line to line would be 240V; in that case likely one blows first but if at high fault current the arc continued it would rapidly blow the other fuse as well (in milliseconds.)

The 1 and 2 pole QO breakers appear to be good for only 120V per pole, and rely on ganged poles to interrupts 240V with two poles in series. Except for the ones with "H" in the part number, and all of the 3-pole breakers.

Yes, a single pole of a 2-pole breaker will be the first to thermally detect overload or magnetically detect high fault current and opens, but because it is ganged with the other pole, the 240V is split across two poles in series and each only has to extinguish a 120V arc.

The 1 pole QO breakers without "H" are rated for use in 120/240V split-phase circuits as well as 120V single phase. Only for 120V L to N. Not for 240V single phase.
 
Hedges said:
Although breakers for 277/480V aren't rated 600V, couldn't be expected to successfully interrupt a 600V circuit.

When 120/240V circuit has fuses, each fuse has to to be good for 240V, because likely only one blows when feeding a 240V heating element load. Fault to chassis would be 120V, and fault line to line would be 240V; in that case likely one blows first but if at high fault current the arc continued it would rapidly blow the other fuse as well (in milliseconds.)

The 1 and 2 pole QO breakers appear to be good for only 120V per pole, and rely on ganged poles to interrupts 240V with two poles in series. Except for the ones with "H" in the part number, and all of the 3-pole breakers.

Yes, a single pole of a 2-pole breaker will be the first to thermally detect overload or magnetically detect high fault current and opens, but because it is ganged with the other pole, the 240V is split across two poles in series and each only has to extinguish a 120V arc.

The 1 pole QO breakers without "H" are rated for use in 120/240V split-phase circuits as well as 120V single phase. Only for 120V L to N. Not for 240V single phase.
Click to expand...
Then how would you explain 2 or 3 single pole breakers on a MWBC (Multi Wire Branch Circuit)?
They will at some point be required to interrupt line to line voltage, when circuits share a neutral. When the loads are balanced, the loads are powered in series by the line to line voltage.
 
Multi-wire branch circuit, so long as neutral doesn't get open-circuit (something I experimented with as a child), the neutral always guarantees each non-ganged single pole breaker only sees 120V max. A multi-wire branch circuit is just 2 or 3 120V circuits.

When loads are balanced, zero current flows in neutral. 2x 1800W 15A 120V space heaters, one on L1, one on L2.
If fed by ganged breaker, when it opens there is 240V across two poles in series.
If fed by individual breakers, when one pole opens it interrupts current to one space heater, 15A 120V. Voltage never rises above 120V because neutral wire picks up the 15A of space heater on other leg.

I can install two single-pole breakers and add a handle tie, then feed a 240V baseboard heater. If I trip one pole, it pulls handle of other pole and opens it too. Everything OK. If I remove the handle tie and trip one pole, that one pole has to interrupt 240V, which I say it is not rated for.

We could set up an experiment with single pole QO15 in a box, L1 from grid to L1 of the box, L2 of grid to N of the box (because I don't have 240V single phase handy.) I would do this through a 70A QO270 from my breaker panel. Likely the QO15 would successfully interrupt 15A 240V, which could be 2x 1800W space heaters in series (something I have), because current isn't high.

If we overloaded it to say 200A at 240V (I don't have any suitable loads), then at such high current and 2x rated voltage I suspect QO15 would burn. After a short while at 3x rated current, QO270 will end the fireworks.

My breaker testing uses transformers to step voltage down, current up. e.g. 480V windings in series with 120V windings (auto-transformer), connected in series with resistive load and fed 120V gives 5x current, 1/5x voltage. Using 1800W space heater, 15A x 5 = 75A, 120V / 5 = 24V. Good for testing what current/time causes trip, but not for interrupt capability at full voltage. We're gonna need a bigger resistor!
 
Then why do QO230 data sheets say "120/240V" and "120V" but not "240V"?
QO230H do say "240V".

Which would you use for corner-ground 240V delta?

Here you go a (an) (HTML) document: [edited because ( n ) without spaces became (n)]


"2P—120/240 Vac Common Trip" "QO230 [4]"
"2P—240 Vac   [3] Common Trip" "QO230H"

"Footnote 3. UL Listed 5 k AIR on corner grounded Delta systems."
"Footnote 4. UL Listed as HACR type for use with air conditioning, heating and refrigeration equipment haing motor group combinations and marked for use with HACR type circuit breakers."

Those applications would be due to the distinction that QO230 is good for 120V per pole, and QO230H is good for 240V per pole.
 
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