But remember, this is a “1950s” installation.
It’s had 70+ years for anyone to screw up with tape colors and wiring.
Open delta question
- Thread starter electrofelon
- Start date
But remember, this is a “1950s” installation.
It’s had 70+ years for anyone to screw up with tape colors and wiring.
ptonsparky
Tom
- Occupation
- EC - retired
That may have been the last time an experienced electrician worked on it.But remember, this is a “1950s” installation.
It’s had 70+ years for anyone to screw up with tape colors and wiring.
as stated yes.
Any reason to add single phase loads to the open phase?
NO don’t do that
The biggest issue with putting single phase loads across the open coils is voltage regulation with the single phase loads switching on and off
MTW
Senior Member
- Location
- SE Michigan
In this thread, he says that it was a steel treating facility that was pre 1950's. I don't think there was even NEC mandated wire color codes back in those days (cloth covered). Using a digital meter will surely add some extra confusion to his understanding.But remember, this is a “1950s” installation.
It’s had 70+ years for anyone to screw up with tape colors and wiring.
A little study and a col;or blind solenoid tester would be in order.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
I know that is stated frequently, but in practice I have never seen the phases marked on a high leg Delta, and without some detective work have no way to know which is which. I don't think anyone does that in practice.
ptonsparky
Tom
- Occupation
- EC - retired
We did it every time, without fail. All the way down to the top of the motor starter. They are common enough in the area, I think most electricians do.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
Isn't the high leg supposed to be taped orange per code?
I think Fellon is talking about a 'phase' as in the set of single phase wires that is the open phase .
Sure we know B is hi-leg, but we never know if A-B or B-C is the open phase.
You'd need a system plaque or label that says something like:
Sure we know B is hi-leg, but we never know if A-B or B-C is the open phase.
You'd need a system plaque or label that says something like:
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Right I was talking about identification of the open phases. I guess some people have found it common to identify them but I have never seen it and I run into quite a few in Seattle.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Cool, maybe those people also use straight rated two pole breakers across the high leg - never seen that done either
ptonsparky
Tom
- Occupation
- EC - retired
The only way I would know if it was an open Delta would be to look at the transformer bank.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
But I thought post #66 you said it was common for them to be labeled with the open phases?
I
the only way I know to identify the open phases would be trace from the bank.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Some have mentioned putting a load on and watch the voltage. I might try that when I get a free moment.
ptonsparky
Tom
- Occupation
- EC - retired
Hi leg Delta can be close, not just open.But I thought post #66 you said it was common for them to be labeled with the open phases?
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Ok I thought you were saying open deltas around you were typically labeled with which are the open phases
kwired
Electron manager
- Location
- NE Nebraska
I took it to mean he has no way of knowing which two phases are the open side of the delta. High leg obviously is one side but the other one is a little harder to determine if you don't have access to conductors at the source. I suppose one could put heavy test load on it and compare voltage readings in different connected scenarios and possibly know which two are the open side.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Only relatively recently, maybe only as far back as the 70's.
Alright here is my first crack at a PI for the open phase identification:
Future PI 110.15
Based on our discussions on loading 3-phase open delta systems with single phase loads it seems there is a need to identify which set of wires is the open phase on these systems. It is import for the electrician to know which set of phase wires / busbars are the open phase so they can make an...
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