Posted By: frank
circuit tracer - 08/22/07 04:53 PM
I had to trace a circuit today and found that the tracer was registering in four different branch panels.What would be the cause?
Posted By: electure
Re: circuit tracer - 08/22/07 05:09 PM
Depending on the type of tester you are using you may need to turn down the sensitivity of the tester to find out which panel/breaker is feeding your circuit.
If the panels share a common transformer, they'll often read right through the system on a high sensitivity setting.
What kind of tester are you using??
Posted By: frank
Re: circuit tracer - 08/23/07 03:44 AM
Sorry that was vague.This may be worse.
I have a three phase 208,120 volt branch panel LE-GB4 where breakers #33 and #2 both signal at the finest setting.At the course setting the tracer also only signals around these two breakers.The same is happening in another branch panel LE-GB2 but with only one breaker.Both branch panels are fed from the same power panel.
We just had new power panels Installed and they had opened and closed the distribution breaker up steam of the old power panels many times during plant shutdowns with no problems.Now anything plugged in to these circuits burn up from a surge as soon as the distribution breaker is closed.(i know they could open the branch panel breakers)
Since this is part of the emergency standby system we think it may happen on a power failure.I have installed some blue Hubble surge suppression 4-plex receptacles for now and it may hide the problem but not fix it.
Posted By: WESTUPLACE
Re: circuit tracer - 08/23/07 01:35 PM
Loose or high resistance neutral. Check ALL neutral and bonding jumpers, both in the distribution & branch panels. Also neutrals on the affected ckt, a loose or bad shared neutral on a 120/208 ckt will surely cause problems like this. Also look for a grounded neutral on a ckt. If you close a main breaker and there is a poor or undersized neutral, but also a ckt with a neutral to ground short, when the inrush current is present as the main is closed, it will try to get a ground (neutral) at the lowest resistance point. This can be the neutral to ground point. (and may be thru the affected equipment) Robert