Dual services... 130-140V to ground?

[u2slow]

I'm working in a building with a 240V 3? service for 'power', and a 120/240V 1? service for 'lighting'.

There are welding plugs (240V 1?) run off the 'lighting' service. The strange part is I get ~130V from one leg to ground, and ~140V from the other leg to ground. [img]confused.gif[/img]

I speculating the POCO is using a high-leg 3? arrangement to supply the two services [img]graemlins/hmmm.gif[/img]

Is my voltage-to-ground reading indicative that the welding plug is not properly bonded? (i.e. measuring delta-system capacitive 'ground' instead?)

I ran out of time on this visit... I'm going to delve into it further next time.

<font color="#a62a2a" size="1">[ May 15, 2005 06:18 PM: Message edited by: u2slow ]</font>

[rmurphy]

Sounds like an interesting one. The answer to these questions may direct your search a bit. What is your voltage at the Panel...line to line, line(s) to neutal, line(s) to bond? Are you getting to same reading at all the welding plugs? How old are the sevices? Good Luck! These little mysteries are a fun part of our trade!

[chris_r]

!

<font color="#a62a2a" size="1">[ June 20, 2005 12:53 AM: Message edited by: Bubb ]</font>

[jbird23]

Originally posted by u2slow:
I'm working in a building with a 240V 3? service for 'power', and a 120/240V 1? service for 'lighting'.

There are welding plugs (240V 1?) run off the 'lighting' service. The strange part is I get ~130V from one leg to ground, and ~140V from the other leg to ground. [img]confused.gif[/img]

I speculating the POCO is using a high-leg 3? arrangement to supply the two services [img]graemlins/hmmm.gif[/img]

Is my voltage-to-ground reading indicative that the welding plug is not properly bonded? (i.e. measuring delta-system capacitive 'ground' instead?)

I ran out of time on this visit... I'm going to delve into it further next time.
<font color="#a62a2a"><font size="1">[ May 15, 2005 06:18 PM: Message edited by: u2slow ]</font></font>

<font size="2" face="Verdana, Helvetica, sans-serif">Hello, I just read your post, in regards to you question 130 volts & 140 volts to ground readings from phase a & b , do you have 240 volts between phases? if not the problem might be at the transformer bank or vault , the transformers might not be calabrated and be on the high side by about 10 to 17 percent which would explain the high reading to ground. each transformer has to to be calabrated at the transformer tap for the specific voltage needed,wether it is a wye or detlta configeration if the calabration is out by 10 to 17 percent, it will affect the voltage at the device or equipment. most devices and/or equipment will accept a highr voltage up to 10 percent over.I do not believe that the problem is in the bonding from the welder to the main panel, unless there is no system ground , in which you will get unusual voltage readings beceause of the delta configuration and no main ground, that should not be the problem if the main electrical system has a main ground and the taps are set correctly wether it is wye or delta.
hopefully this sheds light on your problem, Jason

<font color="#a62a2a" size="1">[ July 02, 2005 06:00 PM: Message edited by: jbird23 ]</font>