Power Company - Electric Meter  - Page 1
Forum section: electronics / repair

author: vidarr
author_rank: Frequent Contributor
timestamp: March 17, 2024, 06:25:53 pm
content: Not sure where to post this, but I found an electric meter in a dumpster at a construction site that looks like it is in very good condition, but it may need some repair. Coincidentally, I am working on an automated hydroponic and aquaponic system and thought maybe I can use this as a meter to record the power usage of the greenhouse. Potentially, the exact power consumption can be separated from the rest of the property's power usage.Since this is mains power and I am not an electrician (but I am an architect and engineer), I want to get some idea of whether this is something I am capable of doing. There are two lines going into the greenhouse; one is for the receptacles (20 amps); another is for the lights (15 amps). Is there an easy way to put this in series with both of those lines?From the pics, it looks like 9, 10, and 11 have the most wear. Ports 9 and 10 still have the copper wire sticking out. It looks like both ports have/had four wires connected. There is a diagram on the front of the meter, but I am not expert enough to know exactly what it means. Would both incoming lines be separated, receptacles and lights (separate live wires and share the neutral) and the outgoing lines sharing those three ports, or do the receptacles get their own two ports and the lights get their own two ports, with the outgoing sharing those four ports?I am still researching this online looking for a manual, or at least someone's explanation. Thought it would be a good idea to post it here, because you guys are smart and probably can explain it better than any other sources.Thank You!edit: I don't know why the forum flips the images upside down. It is very annoying. My apologies.

author: CaptDon
author_rank: Super Contributor
timestamp: March 17, 2024, 08:28:02 pm
content: It was designed for 3 phase operation. I don't know if it will work with two single phases that could be 0 degrees or 180 degrees phase relative to each other Do you know if your two feeds are in phase or reverse phase from each other. The meter has a voltage reference for each phase and the conventional pass through current loop for each phase as well as the ground/earth reference for voltage. Being 'electronic' it may do the additive calculations regardless of relative phase. Try it and see I guess?

author: CaptDon
author_rank: Super Contributor
timestamp: March 17, 2024, 08:34:45 pm
content: They show it as desiring a 'Y' connection. Try it and see. Try to get a close 'guestimate' of what you think it should be reading and then compare to an actual 'usage' as indicated by the meter. It may simply work and be accurate even though you may only be using two of the three phases and the phase relationship won't be the expected 120 degrees.

author: pcprogrammer
author_rank: Super Contributor
timestamp: March 17, 2024, 08:50:31 pm
content: First try it with only one of the lines going to the greenhouse. Only connect one of the phases and the neutral. The two connections in the middle look to be for the neutral wires, so take the line for the sockets (2 wires) coming into the greenhouse and connect them to the left two holes from the middle. (3 and 4 maybe) then connect the two holes right from the middle (5 and 6 maybe) to the greenhouse sockets.Try to see if your mains is actually based on a live and a neutral wire. You can do this with a multimeter and AC voltage measuring to the ground. If both show a voltage of 120V (depends on what is used in your country) then it is not live and neutral, but two live wires with a phase difference.If this becomes to complex already just forget about it. To dangerous to play with.Only when you are sure it is live and neutral you can test it with a single line. Make sure to connect the neutral wires in the two middle holes. When that works you can try it with the line for the lights, but only after making sure it is also based on live and neutral and that the two neutrals on the two lines are the same.Be aware that things can go bang with a flash and that mains voltage is not something to just play with.

author: vidarr
author_rank: Frequent Contributor
timestamp: March 17, 2024, 11:49:03 pm
content: OK, first I will do this:"Try to see if your mains is actually based on a live and a neutral wire. You can do this with a multimeter and AC voltage measuring to the ground. If both show a voltage of 120V (depends on what is used in your country) then it is not live and neutral, but two live wires with a phase difference."I understand what that means in totality and feel comfortable enough to do this. I am almost certain it is a live and neutral setup.Then, I will do this:"Only when you are sure it is live and neutral you can test it with a single line. Make sure to connect the neutral wires in the two middle holes. When that works you can try it with the line for the lights, but only after making sure it is also based on live and neutral and that the two neutrals on the two lines are the same."This I understand, as well, except the part about the "middle holes".Testing the live and neutral I can easily do. Once I determine the live and neutral (I am almost certain that there is a live and neutral, vs phase difference) of say the power to the lights, I need to plug the Live line into which port? and the Neutral line into which port?I ask because I don't understand what you mean by "the two middle holes"; there are two rows, top and bottom. All of the ports/holes are numbered. I can edit the image with photoshop to show the numbers if they can't be seen in the pics. I don't want "that things can go bang with a flash" Ahahaha.Man, I really appreciate the help! I have been learning so much from you guys and this forum!Thank You!!!

author: vidarr
author_rank: Frequent Contributor
timestamp: March 17, 2024, 11:55:57 pm
content: Quote from: CaptDon on March 17, 2024, 08:34:45 pmI live in a "condo" which is in a 10 story building. I believe we are all on a single phase, unless someone needs two phases to their house. The building itself has/uses three phases. Tomorrow I am going to talk to the building manager to see what he knows. This is Brazil. Anything stupid could be the case.

author: pcprogrammer
author_rank: Super Contributor
timestamp: March 18, 2024, 07:25:00 am
content: The numbers are hard to read, and only the bigger holes have screw terminals by the looks of it. Of the smaller holes only two seem to have some sort of connection and these are probably for digital readout of the meter.When you add a picture with clearly numbered holes, I can tell you which numbers are the ones to use, but with the middle ones I mean the ones that on the top, where the screws are, there is no plastic divider between the screws.

author: soldar
author_rank: Super Contributor
timestamp: March 18, 2024, 07:43:42 am
content: The connection diagram is right there, on the face of the meter.Starting from left input phases 1,2,3, and neutral, output neutral, output phases 3,2,1I think you can probably connect a single phase and neutral and it should work.

author: vidarr
author_rank: Frequent Contributor
timestamp: March 18, 2024, 03:39:35 pm
content: Quote from: soldar on March 18, 2024, 07:43:42 amThat makes sense now. I didn't know how to read that diagram. I also verified that there is a neutral line. I also verified that the entire place has no ground wires (except the electric showers).What I don't understand now is if I am taking the two lines, one from the lights, and one from the receptacles, how can I secure both of them in the "phase one" port (with both neutrals going to the first neutral port)? Then, both the lights and receptacles going out from the same, far right, phase one port? They are on separate breakers. Does that matter?It seems like if the receptacles tripped their breaker, they would just "pull" power from the light's line.Could I use the phase one port for the lights and the phase two port for the receptacles? And, I do realize I am using the meter in a way it was not intended, but if it can work like this that would be great. If not, I will put it in the parts bin, or back in the dumpster. No loss.Also, the way it was previously hooked up, they were using ports 8, 9, 10, and 11. All the ports on the right (outgoing) show pretty much no signs of wear.Thank You!

author: pcprogrammer
author_rank: Super Contributor
timestamp: March 18, 2024, 03:52:49 pm
content: Use separate ports for the two live wires to keep at least those apart from each other. The neutrals can be connected if the come from the same mains board.But best to first try with only one and check if the meter is registering any current consumption.Then add the other one and see if you get higher readings that make some sense.

author: soldar
author_rank: Super Contributor
timestamp: March 18, 2024, 04:02:29 pm
content: Quote from: vidarr on March 18, 2024, 03:39:35 pmYou cannot do that. Separate circuits need to remain separate.IFyou have two circuitsAND IFthey both have a common neutralAND IFthe circuit breakers only break the live and not the neutralTHENyou can probably pass one circuit through phase 1 of the meter and the other circuit through phase 2 and the meter should work. It's a shoddy thing to do but it should work.

author: calzap
author_rank: Frequent Contributor
timestamp: March 18, 2024, 06:18:49 pm
content: New, single-phase, single-circuit watt-hour meters can be bought on Amazon and elsewhere for less than US$30. They are UL- or ETL- approved and have a digital display. And show a lot more than watt-hours; things like volts, amps, power factor and frequency. Some have circuit breakers, and some have adjustable alarms.Mike

author: vidarr
author_rank: Frequent Contributor
timestamp: March 18, 2024, 07:54:12 pm
content: Quote from: pcprogrammer on March 18, 2024, 03:52:49 pmI am going to try this tomorrow.

author: vidarr
author_rank: Frequent Contributor
timestamp: March 18, 2024, 07:55:28 pm
content: Quote from: calzap on March 18, 2024, 06:18:49 pmI know, but this was just a random find in a dumpster, not something I was planning to do. If it can work, great; if not, oh well, back to the dumpster it goes.

author: vidarr
author_rank: Frequent Contributor
timestamp: March 18, 2024, 08:02:17 pm
content: Quote from: soldar on March 18, 2024, 04:02:29 pmI am going to make sure the two circuits share a common neutral later tonight. There is a receptacle and light switch right next to each other, so it will be easy to test.Now, whether the circuits breakers break on neutral, this is something I do not know. I imagine the only way I can test this is to connect the two circuits into separate ports (share neutrals) and switch one of the breakers to "OFF"."It's a shoddy thing to do but it should work." Ahahaha. This is Brazil; have you seen our electric showers?

author: drhex
author_rank: Regular Contributor
timestamp: March 20, 2024, 10:26:14 am
content: Also check your breakers, if they are earth leakage circuit types combining neutrals won't work.