I was plugging in my tester to check polarity on a outlet 110v. all lights light up so i thought it meant between nut and hot i had 220. but the strange thing is nut an hot is 120v. hot to ground i have 240v. if u touch pipe u get no shock, how is possible? now the other weird thing is if u shut off breaker tester lights up 1 light that means hot w/no ground. is the trany thats feeding this panel bad? primry voltage 480v w/no ground.
strange voltage readings
- Thread starter vramp7
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
vramp,
Welcome to the forum. Your post is very difficult to read because of your use of abbreviations. If I'm understanding your post it sounds like you maybe you have a 3 phase, 4 wire Delta secondary which is ungrounded.
Welcome to the forum. Your post is very difficult to read because of your use of abbreviations. If I'm understanding your post it sounds like you maybe you have a 3 phase, 4 wire Delta secondary which is ungrounded.
brian john
Senior Member
- Location
- Leesburg, VA
I am not the sharpest knife in the draw so I changed some of the wording of your post to clairify the problem for me , I hope I got the idea of your of the post correct.
I was plugging my tester in to check polarity on an outlet (that should have read) 120vac phase (hot/phase conductor to neutral and ground?). All the lights light up so I thought it meant that between hot and neutral I had 220 (240? 220? or 208?). But the strange thing is the hot (should be?) 120vac (to neutral and ground?). Between the hot to ground I have 240vac (208/220/240?).
If I touch a pipe I did not get a shock. How is this possible?
Now the other weird thing is if I shut off the breaker, the tester lights up with 1 light, which means hot (is energized between, EGC equipment grounding conductor?) ground. Is it possible the transformer that is feeding this panel is bad? I have? need? want? primary voltage of 480vac without a good ground.
1. What is the system voltage 277/480 VAC 3 ? wye, 120/208 VAC 3?wye, 120/240 VAC 3? 4 wire delta, 120/240 VAC single phase, or other distribution system type?
2. Between phase (hot) to neutral you read?
3. Between phase to ground (EGC) you read?
4. Between neutral to ground (EGC) you read?
5. What are the phase to phase, phase to neutral, phase to ground and neutral to ground voltages at the panel?
6. What are the phase to neutral, phase to ground and neutral to ground voltages at the outlet with the CB (circuit beaker) on and with the CB off?.
7. You touched a pipe (what type) and what else did you touch?
8. Did you check to see if te CB is defective?
I was plugging my tester in to check polarity on an outlet (that should have read) 120vac phase (hot/phase conductor to neutral and ground?). All the lights light up so I thought it meant that between hot and neutral I had 220 (240? 220? or 208?). But the strange thing is the hot (should be?) 120vac (to neutral and ground?). Between the hot to ground I have 240vac (208/220/240?).
If I touch a pipe I did not get a shock. How is this possible?
Now the other weird thing is if I shut off the breaker, the tester lights up with 1 light, which means hot (is energized between, EGC equipment grounding conductor?) ground. Is it possible the transformer that is feeding this panel is bad? I have? need? want? primary voltage of 480vac without a good ground.
1. What is the system voltage 277/480 VAC 3 ? wye, 120/208 VAC 3?wye, 120/240 VAC 3? 4 wire delta, 120/240 VAC single phase, or other distribution system type?
2. Between phase (hot) to neutral you read?
3. Between phase to ground (EGC) you read?
4. Between neutral to ground (EGC) you read?
5. What are the phase to phase, phase to neutral, phase to ground and neutral to ground voltages at the panel?
6. What are the phase to neutral, phase to ground and neutral to ground voltages at the outlet with the CB (circuit beaker) on and with the CB off?.
7. You touched a pipe (what type) and what else did you touch?
8. Did you check to see if te CB is defective?
Last edited:
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
Vramp, please write in full sentences.
Look for an open neutral. Sometimes, this will light three lights on a tester.
Take Brian's advice, and test all over the place and let us know what you found.
Look for an open neutral. Sometimes, this will light three lights on a tester.
Take Brian's advice, and test all over the place and let us know what you found.
- Location
- Illinois
- Occupation
- retired electrician
Sounds like the system bonding jumper is missing and one of the hot legs has a ground fault.
Don
Don
It is a very old system from 40s to 50s. as far as i know from my readings its 480v with no ground coming from transformer pad outside. Only 3 wires enter into each 5 -400amp 480v fused disconnects each from outside. I see no ground rod. or form of grounding. but my problem is in the old transformer feeding 2 120-240v panels. That is where im getting weird plug tester readings on both hot phases in panel it does the same thing. 240volt reading from hot too ground. And when the breaker is shut off my plug tester lights up one middle light of 3 showing a hot is present but I dont know how this is possible. Everything works properly lights and things plugged into outlets because from hot to nutrel it reads 120v on meter. im going to take more readings tommorrow.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
What prompted the service call?vramp7 said:
When diagnosing (and for our benefit) be systematic about your measurements and observations. Take everything down about one location, and then move on to the next.
Pay attention to where you are taking your readings from: the screws of the breaker, or the conductor itself.
Be safe, wear your PPE.
dan55
Member
- Location
- South Dakota
two phases on the 480. corner ground delta?
brian john
Senior Member
- Location
- Leesburg, VA
2-phase corner yada yada yada.....
No/yes who knows, because they never called us back......
No/yes who knows, because they never called us back......
- Status