Oh, maybe it ISN'T on a dedicated circuit!

[Rusty.Harris]

We have a school system and all of a sudden (about the time it started getting COLD outside) they complained about a 65ppm color machine (20amp) that starts firing off
fuser errors. Tech replaced the fuser unit and a few days later it did it again. I told him to check the AC socket for a neutral-ground voltage. Also asked if it has an ESP filter
on the circuit and he said yes. Brought it in and I checked. Had over 100 entries in the last 9 months. About 30 for a month. Most were surge/drop outs. This ESP didn't have
the neutral to ground because it was an older one. Tech went back, showed them the printout and he checked the N-G and when the machine was running it was spiking OVER
four volts! He told them to have an electrician check the circuit to make sure it was a dedicated outlet.
Couple days later they said the machine did it again, electrician said the outlet was good bla bla bla.
Couple more yes it is, no it isn't and then one of my supervisor techs went there and had the school electrician with him and he said after seeing the N-G voltage, "oh, looks like
you have a common mode issue" (tech's jaw hit the floor when he said that...DUH! someone gets it).
But the school said it wasn't a problem, so, we pulled a like machine from the other side of the school that service history showed NO issues, and swapped the machines.
NEXT day the machine that has NEVER had a problem, had the same fuser code as the original machine.
And here's the kicker. The school said "oh, well maybe that outlet isn't a dedicated line?" YA THINK?
Most likely some "Susie secretary" doesn't like the cold, plugged in her space heater and is pulling a bit too much juice.
That, or the wiring in the building needs to be replaced.
THIS is why my hair is gray!

[Duplicator]

Good gravy. It's that time of year again isn't it?

I had a similar story once. However, they were plugging their space heater into the same outlet as the UPS on the server rack.... via an extension cord from the office.... Every time the secretary got cold the breaker would trip, the UPS would drain, and the entire network would go down. Arg!

[bsm2]

Pretty easy to tell if on a decated .line trip the breaker and see what else turns off

[slimslob]

In the early days of the RBC 1, the West Coast Royal dealer support tech told me a story about an incident one of his other dealers had encountered. The breaker for the circuit the RBC has on kept tripping but nothing else was affected. It turned out that the wall outlet circuits in that building were single outlets on multiple floors and a secretary 2 floors below had an electric space heater under her desk.

[BillyCarpenter]

Pretty easy to tell if on a decated .line trip the breaker and see what else turns off

I've been down this road before and its not quite so simple. For starters, a school is a big building. Secondly, if the guilty device isn't plugged in, you going nowhere fast.

An electrical diagram of the building would be nice, if its still accurate.

[BillyCarpenter]

We have a school system and all of a sudden (about the time it started getting COLD outside) they complained about a 65ppm color machine (20amp) that starts firing off
fuser errors. Tech replaced the fuser unit and a few days later it did it again. I told him to check the AC socket for a neutral-ground voltage. Also asked if it has an ESP filter
on the circuit and he said yes. Brought it in and I checked. Had over 100 entries in the last 9 months. About 30 for a month. Most were surge/drop outs. This ESP didn't have
the neutral to ground because it was an older one. Tech went back, showed them the printout and he checked the N-G and when the machine was running it was spiking OVER
four volts! He told them to have an electrician check the circuit to make sure it was a dedicated outlet.
Couple days later they said the machine did it again, electrician said the outlet was good bla bla bla.
Couple more yes it is, no it isn't and then one of my supervisor techs went there and had the school electrician with him and he said after seeing the N-G voltage, "oh, looks like
you have a common mode issue" (tech's jaw hit the floor when he said that...DUH! someone gets it).
But the school said it wasn't a problem, so, we pulled a like machine from the other side of the school that service history showed NO issues, and swapped the machines.
NEXT day the machine that has NEVER had a problem, had the same fuser code as the original machine.
And here's the kicker. The school said "oh, well maybe that outlet isn't a dedicated line?" YA THINK?
Most likely some "Susie secretary" doesn't like the cold, plugged in her space heater and is pulling a bit too much juice.
That, or the wiring in the building needs to be replaced.
THIS is why my hair is gray!

I liked the way you handled the situation. I don't think you could have handled it any better.

[Rusty.Harris]

We had another one "back in the day", late 90's. Another school. Customer said machine would reboot. Of course the tech couldn't find any issue with the machine.
Just happened that a tech was there during class change and it did it. On the other side of the wall was a boys bathroom that had recently installed a HOT air dryer.
Yep, that was it!

[bsm2]

I've been down this road before and its not quite so simple. For starters, a school is a big building. Secondly, if the guilty device isn't plugged in, you going nowhere fast.

An electrical diagram of the building would be nice, if its still accurate.

Wow open your ears and learn

Usually anything on a share you can check with your meter
Decated line mean decated . I assume you know how to use one. Or if your company has a power tracker that monitors the device. Yes it's that easy

We also had one on a dedcated line that would power off brand new machine I monitor the line voltage and would drop to 100volts and machine would turn off. Turned out it the neutral line was not tighten down..
Problem solved

[Rusty.Harris]

Follow up!

Tech went back with an electrical engineer and he found the problem. The feed for the circuit for the machine was SPLICED into multiple circuits and the GROUND wires were all
WRAPPED together instead of going to their appropriate grounds.
After they ran the ground wires appropriately, gee wiz! The N-G voltage under load, went from over 4 volts, to 0.02 volts!

Idiots!

[bsm2]

Follow up!

Tech went back with an electrical engineer and he found the problem. The feed for the circuit for the machine was SPLICED into multiple circuits and the GROUND wires were all
WRAPPED together instead of going to their appropriate grounds.
After they ran the ground wires appropriately, gee wiz! The N-G voltage under load, went from over 4 volts, to 0.02 volts!

Idiots!

Good job

[BillyCarpenter]

Follow up!

Tech went back with an electrical engineer and he found the problem. The feed for the circuit for the machine was SPLICED into multiple circuits and the GROUND wires were all
WRAPPED together instead of going to their appropriate grounds.
After they ran the ground wires appropriately, gee wiz! The N-G voltage under load, went from over 4 volts, to 0.02 volts!

Idiots!

I think ground is ground. All grounds go back to the breaker box and all are connected. So, you can tie them all together, or not tie them together, and it's all the same since they all tie back to the EGC. As long as the connection is sound.

[BillyCarpenter]

Wow open your ears and learn

Usually anything on a share you can check with your meter
Decated line mean decated . I assume you know how to use one. Or if your company has a power tracker that monitors the device. Yes it's that easy

We also had one on a dedcated line that would power off brand new machine I monitor the line voltage and would drop to 100volts and machine would turn off. Turned out it the neutral line was not tighten down..
Problem solved

I've never seen anyone with this much confidence that has no idea what he's talking about. If you could read, he said the machine wasn't on a dedicated circuit. Are you with me? Keep following.

In a situation like this, the end goal isn't to locate every outlet on the same circuit. No, the goal is to find the device that is "plugged in" and causing the overload., Still with me? Good.

So, what if the device isn't plugged in? And even if it is plugged in, how do you know which device is overloading the circuit., I could give you the answer, but I'll let you tell us.

[slimslob]

Follow up!

Tech went back with an electrical engineer and he found the problem. The feed for the circuit for the machine was SPLICED into multiple circuits and the GROUND wires were all
WRAPPED together instead of going to their appropriate grounds.
After they ran the ground wires appropriately, gee wiz! The N-G voltage under load, went from over 4 volts, to 0.02 volts!

Idiots!

Many years ago I had a customer running their accounting system on a token star network where the hub for the network was built into the SCO Xenix based server. The receptionist was randomly getting errors. The first few times I went out, everything was working fine while I was there. Then one day while I was there she turned her calculator to use it and I got a shock touching the computer case. It turned out there was a floating ground om the wall outlet and a ground fault in the calculator. With the calculator powered ON the voltage from the computer case to the mount screw for the wall outlet was 60 Volts. That computer had been getting its ground through the shield of the coax cable.

[BillyCarpenter]

Many years ago I had a customer running their accounting system on a token star network where the hub for the network was built into the SCO Xenix based server. The receptionist was randomly getting errors. The first few times I went out, everything was working fine while I was there. Then one day while I was there she turned her calculator to use it and I got a shock touching the computer case. It turned out there was a floating ground om the wall outlet and a ground fault in the calculator. With the calculator powered ON the voltage from the computer case to the mount screw for the wall outlet was 60 Volts. That computer had been getting its ground through the shield of the coax cable.

In a way, you got lucky that you were touching the PC case when she turned on her calculator and saw it when it happened. Electrical shock not withstanding.

[slimslob]

I've never seen anyone with this much confidence that has no idea what he's talking about. If you could read, he said the machine wasn't on a dedicated circuit. Are you with me? Keep following.

In a situation like this, the end goal isn't to locate every outlet on the same circuit. No, the goal is to find the device that is "plugged in" and causing the overload., Still with me? Good.

So, what if the device isn't plugged in? And even if it is plugged in, how do you know which device is overloading the circuit., I could give you the answer, but I'll let you tell us.

I have seen all sorts of power horrors and some of them in new construction.

• Brand new building. Electrician failed to connect the ground/neutral bus of a breaker panel on the second floor to the actual ground. In effect they had the equivalent of 240 differential between L1 and L2. Difference in current loads of devices between the 2 legs resulted in resulted in the power supplies being blown on a dozen new Olivetti typewriters we had just sold a law office
• New wind on a doctor's office. Electrical installer swapped one of the hot legs with the stinger. Smoked 5 or 6 desktop dictation machines. Luckily it only took the builtin surge suppression devices which I was able to replace.