What size wires are the larger ones, the black, red, blue sets?
New range connected to 240v or 208v panel both 3 phase
- Thread starter Nhrafan
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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.
Those readings were conductor directly to ground.
This is the panel opened up...
Attachments
Right, so I looked and the breaker I checked from is the one in the upper left cornerof the photo I posted. So readings are blue=240 black=0 red=240It 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...
Please check voltages with respect to panel space. Space numbers should be (IMO) odd left top to bottom, even right top to bottom.
On the left side of the panel it would start with black so that would match phase A...I believe.
But which conductor...
I mean some parts of PA and OH are really really close... but I suspect yours and my parts aren't that close... nowhere close enough for me to know which conductor you measured voltage to ground.
BTW, that panel is a very uncommon setup in my experience and that's completely regardless of it being a corner grounded system... which is uncommon in and of itself.
As Don mentioned earlier, being a corner grounded system, the grounded conductor is required to be marked white or gray. You can re-identify #4 and larger, but not #6 and smaller. To be Code compliant you may have to pull some wires... old ones out, new white or gray ones in.
You may want to mention it to the boss.
Just nitpicking here, but the three vertical busses on the right side are not Code compliant. They are C, B, A in arrangement and Code requires A, B, C, like on the left side. :angel:
So my next question would be is there any special consideration I should have taken connecting a 3-wire 240v grille to this panel?
Also any consideration to the connections in the 208v panel feed from this one?
Anything I absolutely should make sure of? Like life/death situation or equipment damage?
Also any consideration to the connections in the 208v panel feed from this one?
Anything I absolutely should make sure of? Like life/death situation or equipment damage?
I honestly think there's an awful lot in here that was done without regard to code... That's one main reason I'm here, I want to be careful about what I might be running into and what previous "electricians" have done. :slaphead:
Maybe a really stupid question but....
Isn't a white wire carrying 240v a bad thing?
Oh wait, it's not really supplying 240v though because it's grounded, correct? But the potential between that and the other two conductors supplies that voltage?
MD84
Senior Member
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- Stow, Ohio, USA
Think of some other systems you are familiar with. 120/240v single phase for example. Would you consider the white wire to carry 120v? I would consider it to have a potential of 120v to either of the ungrounded conductors. Same thing with a 208/120v three phase system. The white wire would have 120v potential to any other ungrounded conductor. A 480/277v system will have 277v to the ungrounded conductors. In your situation the corner grounded 240v system white wire has 240v potential to 2 of the lines and 0v to 1 of the lines.
In any case this white wire, or grounded conductor, is bonded to ground. This makes sure the system does not have an uncontrolled potential difference to ground. The ground reference provided by the bonding of the grounded conductor keeps the voltage potential to ground at a known value. It also provides a fault current path back to the source should one of the ungrounded conductors fault to any grounded parts of the system.
It is a safety consideration when looking at voltage potential to ground. Think of the voltage a person could be exposed to if he became the path of current between an ungrounded conductor and a grounded object.
An example I had recently was supplying 240v three phase to some equipment. I needed a transformer with a 480v primary and a 240v secondary. Two possible options are the 480v delta to 240v delta corner grounded and the 480v delta to 240v high leg delta. The 240v high leg delta is a system in which one of the phases is center tapped. This center tap is where the system is bonded to ground. In the case of the high leg delta system, 2 lines will have 120v to ground and 1 line will have 208v to ground.
MD84
Senior Member
- Location
- Stow, Ohio, USA
One consideration is of overcurrent protection of the grounded conductor which should be white or grey and in your case the A phase conductor. No overcurrent device should be used on the grounded conductor unless it simultaneously opens all three conductors. So a fuse is not to be used on the grounded conductor (see 430.36 for motors). A slug can be used in the case of a three pole fuse block or disconnect. A three pole breaker is acceptable. A note on circuit breaker selection: see 240.85. For you application straight rated breakers should be 240v or greater and the lower number of a slash rated breaker should be 240v or greater.
Some code sections to review. Not all are applicable to your situation but worthy of review in general:
230.90 (B) - Service equipment overcurrent protection grounded conductor
240.22 - Overcurrent protection grounded conductor
404.2 (B) - Switch connections grounded conductor
430.36 - Fuses in which conductor (motors)
430.85 - Motor controllers
Sierrasparky
Senior Member
- Location
- USA
- Occupation
- Electrician ,contractor
I have never in all my years seen a panel set-up like this.
What is the purpose?
What is the purpose?
The building wire you are dealing with is rated 600V.... all colors.
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