Beast of Burden

[Chamuit]

I am going to be testing a for a bad neutral on a house. Trying to figure out if there is a bad neutral from the POCO or if the problem is between the SES and the sub panels.

When you are testing for a bad neutral, have any of you use a "beast of burden" to apply an unbalanced load? What do you use to test this?

Just looking for ideas to help me out. Tips trick or hints.

TIA

 

[__dan]

The power company here sometimes uses a 'beast of burden' hair dryer type device. I've told them more than once they can throw it out, only because they plug it in and it tests OK and they drive away. I've had to call back and make sure they promise to climb the pole and yank on / remake the connections.

Last couple of times I just go straight to the washer and pop it in spin cycle for a couple of seconds with the Fluke 87 on it in min max recording. The starting load of the spin cycle is probably a lot more than the big hair dryer. If voltage drops to anything less than 105 or so at starting, I'll keep looking for a bad connection.

A sure tell for a bad neutral with that arrangement, if the voltage drops when the washer spin cycle starts, with a bad neutral, voltage is going high on the other leg at the same time. Look for voltage drop at the washer and then check the other phase to neutral voltage again (for the voltage to go higher) with the washer starting spin

Without thinking too much about it, I usually go in order, pop the main panel cover and take a look or a screwdriver to the mains, same at the meter socket, walk the overhead triplex to look for burned crimp barrels, look at the triplex for tree branches rubbing on the drop. Then I go to the electric range and turn on one or two burners and make sure they heat and the lights do not go brighter / dimmer. Next is the washer load with the Fluke 87 and after that is the call to the utility that I've checked and the bad connection is probably outside.

 

[renosteinke]

I had a house that was driving me nuts ... absolute first-class wiring job, and the guy kept having appliances die. As luck would have it, I was at the panel, meter on the feed, one time when the 'surge' happened. Sure enough, the neutral tap at the transformer was bad. Only after the PoCo had fixed it did the two other homes served by that same tranny admit that they too had experienced issues.

All I can suggest, for an intermittent issue such as this, to put a recording meter on the feed from the PoCo. I believe Fieldpiece has such a datalogger for about $185. If your volts coming in are all over the map, chances are it's the PoCo. If you've killed your main, then there's no doubt.

 

[hurk27]

If I have to test, it's more likely because I have a city water ground feeding to another service providing a return path, you can used the loads on 1/2 the panel as a load tester, first thing I always do is turn off every other phase breaker in the panel, and any two poles, so that only one leg is loaded, turn off the main and lift the water ground then turn the main back on, be carefull as you will have 120 volts on the grounding if you have a bad neutral, then if you can measure 120 volts to ground from the meter can, to earth you have lost the neutral at the riser or at the pole.

Also if they have cable TV disconnect it at the grounding block as it will also provide a path to the MGN, and can burn up under a load.

Just make sure you know where everyone is, that no one goes near anything grounded to the service.

Using a load bank with the water ground connected can give a false indication of a good neutral, any this is what happens with many service men from the POCO's. you have the same danger when using a load bank that can damage equipment and put a raised voltage on the grounding, so even using a load bank, make sure you shut off the main and or branch circuit breakers, and make sure no one is near anything grounded, lift the water ground if a city supply, and cable is disconnected, before you load the neutral.

 

[220/221]

Call APS/SRP first and let them load test their end.....for free. APS has a slick unit with two meters built in. They flip a switch to load either 1500 or 3000 watts to one leg at a time and the voltage for both legs is displayed. The SRP guys use this 1000 watt old ass soldering iron looking thing with one hot lead attached to a screwdriver. Safety first


I usually use something handy with a heating element. Sometimes I'll bring my PVC heater. Other times a space heater, hair dryer or toaster.

 

[Chamuit]

It's APS. They came out and put their tester on the SES voltages were "okay". Did a visual on the pull section. This panel is about 5 years old and they have been having problems before this panel was put in. Making me think that the source power is the problem. It could be the feeder wires from the main section and to the sub panels as well.