You missed 240v.
New range connected to 240v or 208v panel both 3 phase
- Thread starter Nhrafan
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texie
Senior Member
- Location
- Fort Collins, Colorado
- Occupation
- Electrician, Contractor, Inspector
You missed 240v.
Yep.
It would be interesting to see what the 240 panel really is though and why it is there. And does it come that way from the service. Could be 240Y/139, 240/120 delta center tapped or far more unlikely 240 delta ungrounded or 240 delta corner grounded. Since the OP seems like a good sport, shall we tell him how to determine this with a volt meter?
Have at it...
So I went and shut the power off today and fully opened the panel up and started to do the work. I removed several circuits no longer in use and removed those breakers, almost all 20a breakers, 9 in total.
I found that everything can be operated from the 208 panel except for the indoor grill which specifically states 240V but that only has 3 wires so I'm okay going into the other panel with that, there's no neutral it's just heating elements.
I was able to connect the exhaust hood (11a draw on a 20a breaker) and 2 refrigerators, each on a 20a breaker. Now I have the coffee maker (30a in 208 panel), the grill (3 wire going into the 240v panel) and the range (50a into the 208v panel) to connect but need to finish up conduit runs down to the boxes first thing tomorrow.
I found that everything can be operated from the 208 panel except for the indoor grill which specifically states 240V but that only has 3 wires so I'm okay going into the other panel with that, there's no neutral it's just heating elements.
I was able to connect the exhaust hood (11a draw on a 20a breaker) and 2 refrigerators, each on a 20a breaker. Now I have the coffee maker (30a in 208 panel), the grill (3 wire going into the 240v panel) and the range (50a into the 208v panel) to connect but need to finish up conduit runs down to the boxes first thing tomorrow.
You missed 240v.
You are certainly correct sir! I knew I was forgetting something.:thumbsup:
Yep.
It would be interesting to see what the 240 panel really is though and why it is there. And does it come that way from the service. Could be 240Y/139, 240/120 delta center tapped or far more unlikely 240 delta ungrounded or 240 delta corner grounded. Since the OP seems like a good sport, shall we tell him how to determine this with a volt meter?
Ok well here's the plate on the transformer feeding up top the main panel (panel 1)
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MD84
Senior Member
- Location
- Stow, Ohio, USA
Well it looks like a separately derived system. I wonder if it is properly bonded to ground. A check of voltage from each phase to ground would be telling.
This is the feeder panel and transformer, have not opened but this is what I will shut off tomorrow to work in the 240V panel, so I could.
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- Location
- Illinois
- Occupation
- retired electrician
Any conductors connected to A phase in that panel are required to be identified as grounded conductors....white or gray.
Well this is new to me. Can you or anyone else explain further? :?
I was able to remove the face panel and sneak a peek inside, snapped a few pictures and this is one:
I don't see much white or gray at all...?
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JFletcher
Senior Member
- Location
- Williamsburg, VA
Make sure that any breakers you use in the 240V panel are not 'slash rated' and say 120/240V. You must use breakers rated straight 240V since line to ground is above 120V.
That pic of panel #1 says "Phase A - Grounded", which means you have a 240V corner grounded delta.
That pic of panel #1 says "Phase A - Grounded", which means you have a 240V corner grounded delta.
Although the ones that are there go into the other panel, looks like they are a type of gfi breaker with a neutral connection?
I believe the breakers in the panel are labeled "shunt trip" also
- Location
- Illinois
- Occupation
- retired electrician
The disconnect says that A phase is grounded. This is a corner grounded system. The conductor connected to A phase is a grounded conductor and the rules in Article 200 apply.
To be sure that you really have a grounded system, you need to check the voltages. If A phase is grounded you will have the following voltages.
A to Ground = 0
B to Ground = 240
C to Ground = 240
A to B = 240
B to C = 240
A to C = 240
Check voltages per Don's post.
The grounded conductor of a corner grounded system is treated almost identical to a grounded neutral of a more common system. In some cases, you cannot tell the difference just looking at how the panel is wired. However, not all corner-grounded-system panels are wired the same. Some use two ungrounded busses and grounded bus, just like a single phase 120/240V 1Ø 3W panel. Some use all three busses of a 3Ø panel and switch the grounded conductor.
The shunt trip breakers may be for air handlers which are tied into the fire system.
texie
Senior Member
- Location
- Fort Collins, Colorado
- Occupation
- Electrician, Contractor, Inspector
Well gee, kind of an odd setup but you did say that you had the whole range of systems in the building. It seems that you are suggesting you have a 408Y service feeding some loads plus this transformer and this transformer is then feeding some other 240 loads plus the 208Y transformer. Who knows, maybe the building started life as a 240 volt system with no neutral as I mentioned earlier and evolved to need 480 and they ended up with the 208Y system tranformed twice to get there.Kind of an inefficient way to get 208Y, but hey, it works. But just speculating as we are not there.
Just be aware the the corner grounded system has some unique code requirements and limitations as others indicated.
Was just able to finally check, checked off of a 3 pole breaker: top lug=245 middle lug=0 bottom lug=247
What circuit number(s) is the breaker plugged in to?
It appears corner grounded (assuming the values posted are line to ground) and using a 3Ø bus panel... but that doesn't tell you which phase is grounded. The middle lug of a 3P breaker can be positioned in the panel to connect to any one of the three busses.
Busses should be ABC left to right and spaces should be ABC top to bottom, but you should verify and check the lines are actually connected that way. It is commonplace to wire panels corner grounded B phase (some are actually labeled and sold as such)... but that's not supposed to mean one should flop from a designated grounded "A" phase to match wiring a panel as Grounded "B" phase.
That could get someone really confused. Could be catastrophic...
hmy::blink:Please check voltages with respect to panel space. Space numbers should be (IMO) odd left top to bottom, even right top to bottom.
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