Another High Leg question

[Marty Funkhauser]

In a high leg panel could you use a straight rated 240volt breaker on the B phase to control a base board heater rated at 208v. So you would have 12-2 nm at load lets say with the white reidentified. I watched a Mike Holt live stream a few weeks ago, and he talked about a high leg system so it sparked my curiosity. Also what kind of loads have you done with that arrangement ( b phase and neutral ) Thank You

 

[kwired]

In a high leg panel could you use a straight rated 240volt breaker on the B phase to control a base board heater rated at 208v. So you would have 12-2 nm at load lets say with the white reidentified. I watched a Mike Holt live stream a few weeks ago, and he talked about a high leg system so it sparked my curiosity. Also what kind of loads have you done with that arrangement ( b phase and neutral ) Thank You

You could, but you likely won't find a single pole breaker rated for 240 volts unless you make the jump up to a line of 277/480 rated panel and breakers.

You wouldn't reidentify the white if it is landed on the neutral either.

You can use a 240 volt rated 2 pole breaker (straight 240 and not a 120/240 rating) and supply a 240 volt load with one pole on high leg and one on either other legs. ADD: or you could use a straight 240 double pole and just use one pole, but may as well use both in most situations.

3 pole breakers are rated straight 240 volts and you don't have to pay attention to this detail with them.

 

[zbang]

. Also what kind of loads have you done with that arrangement ( b phase and neutral )

IMHO, none. (Please see the previous discussions for all of the reasons.)

 

[Marty Funkhauser]

You could, but you likely won't find a single pole breaker rated for 240 volts unless you make the jump up to a line of 277/480 rated panel and breakers.

You wouldn't reidentify the white if it is landed on the neutral either.

You can use a 240 volt rated 2 pole breaker (straight 240 and not a 120/240 rating) and supply a 240 volt load with one pole on high leg and one on either other legs. ADD: or you could use a straight 240 double pole and just use one pole, but may as well use both in most situations.

3 pole breakers are rated straight 240 volts and you don't have to pay attention to this detail with them.

Thank You for the knowledge

 

[Marty Funkhauser]

IMHO, none. (Please see the previous discussions for all of the reasons.)

I'll search the topic. Thank You

 

[oldsparky52]

Bottom line is don't.

 

[Jraef]

Bottom line is don't.

Yes. Please think of the NEXT guy to come along on this and not know what you did. Using the B phase + neutral is not something that anyone does. So someone coming across a piece of equipment that is wired L-N, it would be reasonable to expect it to be 120V, not 208V.

 

[Chamuit]

Yes. Please think of the NEXT guy to come along on this and not know what you did. Using the B phase + neutral is not something that anyone does. So someone coming across a piece of equipment that is wired L-N, it would be reasonable to expect it to be 120V, not 208V.

Agreed, especially in residential work.

I got called to a job two weeks ago by a technician that was unfamiliar with 3P Delta freaking out because he had 208V on one leg. Thought the house was going to burn down. The previous electrician(s) had not marked the high leg with orange. 2 Condensers one on A-B the other on B-C at least.

There are a lot of young guys with zero exposure to anything 3P.

 

[rambojoe]

Agreed, especially in residential work.

I got called to a job two weeks ago by a technician that was unfamiliar with 3P Delta freaking out because he had 208V on one leg. Thought the house was going to burn down. The previous electrician(s) had not marked the high leg with orange. 2 Condensers one on A-B the other on B-C at least.

There are a lot of young guys with zero exposure to anything 3P.

It pays to read the meter sometimes, or at least a glance. There are still many of these services around phoenix (for some reason) but, the meters look way different than a standard 120/...they are much longer, and even a small little tube or something on the face- along with the voltage of the service...

 

[zbang]

There are still many of these services around phoenix (for some reason)

Years back, I was told this was for very early air-conditioning systems; I guess the single-phase compressor hadn't been worked out yet. (Apparently, Galveston TX also has some.)

And yes- check the meter, check the voltages, and if something seems "weird", find out why.

 

[jim dungar]

Years back, I was told this was for very early air-conditioning systems...

The high-leg (center tapped delta) 240/120 3PH 4W service has been around for some 90 years. I don't know of any part of the country that does not have these systems in older building. Yeah, they are typically not found on new services, but they are not extremely rare, like 2-phase is.

 

[zbang]

Phoenix had them for residential services, I thought that's what rambojoe was talking about.

 

[ActionDave]

Phoenix had them for residential services, I thought that's what rambojoe was talking about.

Yes. And they had what was called a Delta breaker that looked like a four pole breaker, but it was really taking the A and B phase from the panel buss and C phase from the power pole outside. Interesting if you've never seen one.

 

[ptonsparky]

I remember working at an older really NICE home that had a water cooled central air with three phase high leg just for it. I had already smoked my first drill via temp power, so that system wasn’t new to me but it was my first for a residence.

 

[Chamuit]

It pays to read the meter sometimes, or at least a glance. There are still many of these services around phoenix (for some reason) but, the meters look way different than a standard 120/...they are much longer, and even a small little tube or something on the face- along with the voltage of the service...

Yep. Central Phoenix even Arcadia is where they are at. I replaced quite a few in the Encato area.

 

[don_resqcapt19]

Often the homes with 3 phase AC equipment used a "delta" breaker, and the high leg was not connected to anything other than the AC equipment. This breaker is installed in a single phase panel, but has an extra termination. Tow phases are from the bus in the panel and the service conductor for the high leg is directly connected to the delta breaker. This way there is no 208 on the panel bus. but you still have the high leg energized when you turn of the 2 pole main breaker.

 

[LarryFine]

I've mentioned this before. A friend's parents' house had a high leg brought to the house solely for the A/C compressor.

An outside disconnect for the compressor was fed directly through the meter; the high leg never entered the house.