Trouble finding straight 240v breaker vs 120/240 breaker

[winnie]

Here is an old Eaton article on slash rated breakers:

https://www.eaton.com/content/dam/eaton/products/electrical-circuit-protection/fuses/solution-center/bus-ele-tech-lib-slash-rated-devices-1.pdf

 

[hillbilly1]

Yes but it's being enforced.

I need to know the why.

Put in a 3p breaker or step up to a 277/480v breaker where a 2p breaker is needed just to satisfy a voltage rating that seems to already cover the voltage? Seriously?

There's got to be a better reason.

JAP>

How do you sell a product very few people want? Make it illegal not to use it.

 

[jap]

How do you sell a product very few people want? Make it illegal not to use it.

The reasoning Jim posted put some logic behind it.

JAP>

 

[jap]

Here is an old Eaton article on slash rated breakers:

https://www.eaton.com/content/dam/eaton/products/electrical-circuit-protection/fuses/solution-center/bus-ele-tech-lib-slash-rated-devices-1.pdf

That pretty well sums it up.
As Jim said the high leg to ground voltage would be much closer to the full phase to phase voltage rating of 240v.

Thanks,

 

[winnie]

It has to do with the breakrrs internal ability to safely clear a fault.
A fault on a 120V to ground circuit can be cleared fairly easily so the breakers can be made cheaply
As the voltage nears 240V to ground the internal arcing paths need to be changed resulting in a more expensive internal construction.

If you have a 120/240V system, for the breaker to see a 240V fault, the fault is very likely flowing in series through _two_ breaker poles. Additionally a single line-ground fault is probably more likely than a line-line fault.

So it is plausible that breaker rated 120/240V can be more cheaply built than a straight 240V breaker, and that manufacturers would want to use cheaper if possible.

With that said, I echo @jap about the _actual_ difference (as opposed to the plausible hypothetical difference) between 120/240V breakers and straight 240V breakers. I wonder if as a practical matter the breaker mechanisms in reality the same for 1, 2 or 3 pole breakers, and if the only difference between a slash rated 2 pole breaker and a straight rated 3 pole breaker is the testing, at least for these low voltages.


-Jon

 

[jap]

Fortunately in my area 240v Delta High leg services are quickly becoming a thing of the past.

I never was a big fan of em anyway.

JAP>

 

[tom baker]

Fortunately in my area 240v Delta High leg services are quickly becoming a thing of the past.

I never was a big fan of em anyway.

JAP>

Same here our POCO no longer has it available

 

[hillbilly1]

Just picked up a theatre customer that has a delta service. 2-200 amp panels, one three phase, one single phase. Not a thing in the three phase panel. Apparently the local electricians were scared of the three phase!

 

[electrofelon]

I am trying to find a 240v breaker vs 120/240 breaker for buddy of mine. This is because they are replacing a breaker for a water heater and one of the phases is the high leg delta. I suppose worse case scenerio they can go with a 277/480 rated 2 pole breaker if it can fit the panel board, am I correct on this? there is no code violation on using this correct?

Back to the OP, what kind and brand of panel is it? If it is a bolt-on style panel board then yes you can use a 277/480 breaker, for example with Siemans it would be a BQD. If it's a stab on, I'm pretty sure everyone makes a straight rated breaker. For Siemens it has an R suffix, i.e. Q230R (I recently priced them they are about a hundred bucks). For SQ D it's an H suffix, i.e. QO230H. Not sure what the part number is off hand for Joseph Eaton. All three poles are straight rated so you can also use a three-pole. (Some of this has already been mentioned, just summarizing).

 

[kwired]

Back to the OP, what kind and brand of panel is it? If it is a bolt-on style panel board then yes you can use a 277/480 breaker, for example with Siemans it would be a BQD. If it's a stab on, I'm pretty sure everyone makes a straight rated breaker. For Siemens it has an R suffix, i.e. Q230R (I recently priced them they are about a hundred bucks). For SQ D it's an H suffix, i.e. QO230H. Not sure what the part number is off hand for Joseph Eaton. All three poles are straight rated so you can also use a three-pole. (Some of this has already been mentioned, just summarizing).

QO - H series is a 240 volt rated breaker. To get a 277/480 rated breaker in Square D current offerings you need to go to the NF series breakers, they will not fit in a QO series panel, so to use one you will be installing a NF panelboard, can't just bolt it on to panelboard with QO bolt on bus types.

 

[kwired]

Don’t know of any that will install in a 240 volt panel. Like MTW posted, use a three pole if you have the room.

And it likely cost same or more than the three pole anyway.

Plus the two pole might not stocked where the three pole likely is. If it is Square D and you are waiting for factory order on this, it might take months to get it as well.

 

[electrofelon]

QO - H series is a 240 volt rated breaker. To get a 277/480 rated breaker in Square D current offerings you need to go to the NF series breakers, they will not fit in a QO series panel, so to use one you will be installing a NF panelboard, can't just bolt it on to panelboard with QO bolt on bus types.

That seems like a dumb design. With Siemens, the 240V bolt ons (B230) are physically the same as the 480 bolt ons (BQD230, of course there are other 480 ones, the BQD's are just the basic standard ones). In fact I have ordered 120/208 panelboards and had it come with a mix of B and BQD breakers.

 

[electrofelon]

I looked it up and for a Eaton BR its an "H" suffix, i.e. BR230H. This is also their "high mag" breaker.

 

[kwired]

That seems like a dumb design. With Siemens, the 240V bolt ons (B230) are physically the same as the 480 bolt ons (BQD230, of course there are other 480 ones, the BQD's are just the basic standard ones). In fact I have ordered 120/208 panelboards and had it come with a mix of B and BQD breakers.

That would allow the 240 volt breaker to bolt into the 480 volt panel. And you know that there likely is some installed that way somewhere.

They don't make 240 volt fuses that fit in a 600 volt fuse holder. (Edit: someone may probe me wrong, and I do know of some miniature fuses that will interchange here)

Square D's exception to this is the I-Line series panels and breakers. But your typical DIY or jack of all trades maintenance man isn't messing with those as often as the other series panels either.

 

[LarryFine]

. . . someone may probe me wrong . . .

I hate it when that happens.

 

[MTW]

That would allow the 240 volt breaker to bolt into the 480 volt panel. And you know that there likely is some installed that way

I have seen that at a few plants I have worked at, panels full of 240V breakers on a 480V system. Some sparky trying to make a few extra $, and putting personal at risk for the savings.

 

[electrofelon]

That would allow the 240 volt breaker to bolt into the 480 volt panel. And you know that there likely is some installed that way somewhere.

They don't make 240 volt fuses that fit in a 600 volt fuse holder. (Edit: someone may probe me wrong, and I do know of some miniature fuses that will interchange here)

Square D's exception to this is the I-Line series panels and breakers. But your typical DIY or jack of all trades maintenance man isn't messing with those as often as the other series panels either.

I guess but who cares, someone could put in the correct voltage breaker but a much larger amperage than the conductors. Or one with an under rated AIC. How far do we go to try to brother-in-law proof something? I like the Siemens design because it results in more interchangeable parts. Also it is often prudent to use a 480 breaker on a 208 system where you need a high AIC (a BQD has an AIC of 65k @240v). And of course there is this exact case we are talking about of a Delta system with 208 to ground. But anyway, thanks for the correction I just assumed everybody's 480 breakers were the same as their 240 bolt-ons. Anyone know offhand if this is true for Eaton and GE? I think it's a TEY for a typical GE 480 breaker, will that fit in their 240 volt bolt-on panel boards?

 

[electrofelon]

I hate it when that happens.

Aliens...

 

[electrofelon]

I have seen that at a few plants I have worked at, panels full of 240V breakers on a 480V system. Some sparky trying to make a few extra $, and putting personal at risk for the savings.

And really, what's the stop someone from using a 240 volt panel board on a 480 system? Never underestimate the brother-in-law. I saw that once, guy was putting a square d load center on a 480 system

 

[hillbilly1]

And really, what's the stop someone from using a 240 volt panel board on a 480 system? Never underestimate the brother-in-law. I saw that once, guy was putting a square d load center on a 480 system

I looked at one job, brand new store (takeover existing building) someone put in an entire 208 volt switchgear on 480 volts! Gear had to be less than 10 years old. How they got it past inspections and energized I don’t know, unless the inspector didn’t know it was going to be 480. Had to give a quote on ripping it out and replacing.