Could Ground Connection Induce Spark?

Hi,

If I understand you correctly, that means the hour meter works in this type of connection (I thought it wouldnt work). And if the panel ground become ungrounded, the panel would have 240V? I sketched the connection in case i am not clear in my first post. Could connecting the ground from the receptacle to the generator neutral solve the problem?

Yes to both questions.

Hi,

In the given situation, suppose you connect the hour meter between a phase (say "Red") and earth. If there is an earth fault in another phase (Say "Blue") then hour meter will see 415V instead of 240V. It may get damaged and may give spark also in this condition.

As also said, if there is a earth discontinuity, hour meter may not work properly and 240V will stay in the earth line. Assume earth line is disconnected with a small gap or loosely made earth connection somewhere, spark may arise in that location.

Even there is hazardous area enclosure for the hour meter, this situation is to be avoided. You have to connect the hour meter between Phase and neutral of generator only.

Regarding grounding of generator neutral, you have to see check few points. Like whether protection is adequate, can generator be shutdown in case of faults.

According to the sketch above, the original poster's hour meter is in an EEx p panel. So even if it did go phut on 415V, there wouldn't be a flammable gas/air mixture in the panel with which to cause an explosion.

It's interesting that the original poster hasn't stated how the EEx p protection is provided within this panel. Another "rat's nest" from the sub-trained electrician that installed the hour meter between phase and earth, perhaps?

I would be more concerned about the installation of the meter in the panel. In whether he may have defeated the hazard rating. There are sparks from the motor contacts making and breaking with every use of the pumps. Also is the hour meter rated for the environment. It may not be sealed to prevent gases from passing though it into the panel.

If the panel were in the non-hazardous area, or were it in the hazardous area and its enclosure EEx d or EEx p then there would be no concern, as this possibility is covered by the hazardous area assessment, which should be on record somewhere in the facility.

Of greater concern would be a voltage appearing on a disconnected ground somewhere else during earth loop testing and the potential for electric shock to the person carrying out the test.

• Neutral is the return curent-carrying conductor. Always.
• Ground/earth is there solely to operate the circuit protective device in the event of a fault occurring. Always.

One wonders if the electrician that connected this particular hours run meter was adequately qualified, and whether there is a "rat's nest" of similar installations elsewhere in the facility....

I agree with you on that a neutral should have been run. As far as the meter is concerned generally they are rate NEMA 3. From experience any where on a drilling rig can come be a potential hazardous area. Have a friend that I worked and partied with get caught in a gas release that ignited. The source of the ignition was the manifolds on engines driving the mud pumps. That he had shut down. This was land based rig. The pumps are not on the rig floor.

Hi,

In regards with your comment on neutral being the current-carrying conductor and ground being solely for fault protection.

In my case, if I were to connect the ground from receptacle to the generator neutral, current would flow through to the neutral to complete the circuit and would not flow through the ground. Am i correct?

Is grounding generator neutral a normal practise? What if the neutral is not grounded at all? What are the impacts?

They used to use neutral for grounding, but those times are now gone. It worked good... until something like lose contact occurred. It is potential danger, and now it is not a good practice to put intentionally current-carrying conductors on non-current-carrying metal parts; Equipment Grounding Conductor (the one you connected to the grounding slot of your receptacle) is normally non-current-carrying conductor; it shall never be connected to the neutral in any other place but service equipment where it is bonded to the neutral. After that these two wires are separate, of different colors and purposes. Neutral is normally current-carrying conductor, is not intended to touch metal parts; Equipment-grounding conductor is not current-carrying, intentionally put on metal parts of equipment and/or devices. Its purpose is to carry ground-fault current (if phase accidentally touches metal parts) to the point where it is bonded with neutral. Neutral is grounded conductor, so, the equipment (device) is grounded with EGC and there is no potential between earth and equipment.

Generator neutral grounding is a very normal practice. Neutral has the smallest potential with phases, that is why it is chosen to be grounded (some systems do not have neutrals, then they ground one of the phases <sounds strange, but it is necessary to ground one of the wires>).

What if not grounded? Then you can touch any phase, and nothing will happen to you, because there is no complete circuit back to the source. However, if the accident happens, like one wire falls on the ground, you will have potential between the earth and your equipment; grounding will eliminate this potential, and you'll be safe.

<...In my case, if I were to connect the ground from receptacle to the generator neutral, current would flow through to the neutral to complete the circuit and would not flow through the ground. Am i correct?...>

No.

<...Is grounding generator neutral a normal practise? What if the neutral is not grounded at all? What are the impacts?...>

Read the wikipedia article on grounding systems. Get that fuzzy-headed electrician trained adequately before there is another Piper Alpha or Deepwater Horizon.

Quite.

I think you should used proper netural instead of ground point and this the safest way to connect energy meter.Pl. check the following diagram for better unerstanding.

The connection to ground is highly illegal, and some one, could get HURT....! If a neutral isnt available, then the solution is to install a 415-240 transformer, The hour meter is connected to the secondary (240V) side, with suitable protection, (fuses or circuit breaker) in both poles. Norm.

It is okay if he connected to one phase but, in order to get 240v that is accomodated by the meter, he should connect neutral wire that would be coming from the neutral bar and again he should get another meter and connect it to the second phase using the same method.Then that way he would be reading the consumption per hour from each phase.The remaining two terminals in each meter would be then going to the load, in this case a starter.

This is my answer, that is if I understood the question correctly.

The original poster stated it was an hours run meter, not a consumption meter.

As PWslack said you have to maintain the same ground potential in the generator and the receptable to connect the Hour meter to the ground, thats the only safe way you can work on it.

If all connections are properly made I see no problem from here, which is well out of range. The fact he tied in to one leg if power presents no hazard I'm aware of as long as proper connections were made. Joe

Will you keep the NOISE down? Some of us are trying to sleep! <wheeze, splutter>