# Fault on a tri-phasic circuit

I work on a industry as an intern and I'm having a trouble. Clearly there's a fault on the net, but I can't figure out which type it is since I'm having strange readings from a basic multimeter. I'm in Minas Gerais, on Brazil, where each phase have 127 V and here it's a very common practice the neutral grounded (there's no difference between the ground and neutral). So, let's go on.

When I measure each live to neutral it gives me 127 V, also does ground to neutral.

When I measure each live to ground:

A to GND: 220 V

B to GND: 0 V

C to GND: 220 V

Neutral to GND: 127 V

If we change the reference a possible voltage on conductors are as follows:

A: 127 /-120°

B: 127 /0°

C: 127 /120°

Neutral: 0

GND: 127 /0°

Anyone have an idea of what's my problem? What's the simplest/cheapest way to solve it?

Thx very much

• The electrical installment is roughly projected and done. Also we do not have a plant and possible the circuit breakers are badly dimensioned. Feb 2, 2015 at 9:24
• It seems like B and Neutral are flipped. Feb 2, 2015 at 9:34

The relationship between phase voltage and line voltage (difference between two phase voltages) is $\sqrt3$ = 1.732. If you multiply 127 by 1.732 you get 219.9 volts. This should reliably tell you that line B is grounded instead of neutral.