Saturn_Europa
Senior Member
- Location
- Fishing Industry
- Occupation
- Electrician Limited License NC
I work for a humanitarian organization in Borno, Nigeria.
I am in charge of the electrical work in a new hospital we are building. The old hospital called me with an emergency and this is what I showed up to.
I replaced all damaged wiring and breakers. It was a complete rat nest and an absolute disaster. After the repair I tested voltages. Please note 230v/400v three phase system.
N to Phase 1 : 230 v
N to Phase 2 : 400 v
N to Phase 3: 230 v
N to ground: 230 v
At the generator: the frame of the generator to the neutral on the main 4 pole disconnect it was 230v.
I went to the main distribution board and turned breakers off until the voltage returned to normal. 230v phase to N and 400 v phase to phase. The problem was the breaker to the Ministry of Health's MOH offices.
My theory is that its essentially an ungrounded system. One phase went to ground at the MOH offices and thats what caused the crazy voltages. When another phase went to ground it caused the fire.
From the frame of the generator to the neutral at the generator main breaker there is 80 ohms.
There is only 4 wires from the genset to the main disconnect. Its 4 core armored cable from the main disconnect to the distribution board. The armored metal is cut back and not grounded to anything. There is a ground at the distribution board but from what I can tell its going directly to ground rod and not carried back to the source.
My solution is bond the neutral to genset frame. Then carry the ground wire to the main distribution board.
The organization I work for has done TT grounding systems in the past. I really dont want to screw anything up 4 weeks before we leave this hospital and move to the new one with a proper TNS system.
Is it possible that what I was reading was a open neutral?
I am in charge of the electrical work in a new hospital we are building. The old hospital called me with an emergency and this is what I showed up to.
I replaced all damaged wiring and breakers. It was a complete rat nest and an absolute disaster. After the repair I tested voltages. Please note 230v/400v three phase system.
N to Phase 1 : 230 v
N to Phase 2 : 400 v
N to Phase 3: 230 v
N to ground: 230 v
At the generator: the frame of the generator to the neutral on the main 4 pole disconnect it was 230v.
I went to the main distribution board and turned breakers off until the voltage returned to normal. 230v phase to N and 400 v phase to phase. The problem was the breaker to the Ministry of Health's MOH offices.
My theory is that its essentially an ungrounded system. One phase went to ground at the MOH offices and thats what caused the crazy voltages. When another phase went to ground it caused the fire.
From the frame of the generator to the neutral at the generator main breaker there is 80 ohms.
There is only 4 wires from the genset to the main disconnect. Its 4 core armored cable from the main disconnect to the distribution board. The armored metal is cut back and not grounded to anything. There is a ground at the distribution board but from what I can tell its going directly to ground rod and not carried back to the source.
My solution is bond the neutral to genset frame. Then carry the ground wire to the main distribution board.
The organization I work for has done TT grounding systems in the past. I really dont want to screw anything up 4 weeks before we leave this hospital and move to the new one with a proper TNS system.
Is it possible that what I was reading was a open neutral?
