MEP-003A hook up question

wsmolloy

New member
5
0
0
Location
West Palm Beach FL
Maybe wrong thread. I clean the gauge and it appears to constantly hold at about 67HZ. After shutting down it now has no output zero Volts on the meter, zero volts on the lugs. Any thoughts why it would work then 5 minutes later not work?
 

screejunk

Member
48
2
8
Location
Vermont
Keep in mind I do not own a MEP-003a, but do own a smaller 3kw MEP-701a and have skimmed over the MEP-003a TM. First a little basic theory your generator internally is either a 6 or 12 lead reconnectable generator (the distinction does not matter for our purposes here) these leads are reconnected in various combinations by the voltage selector switch by the circuit breaker (never turn this switch with the unit running). In practical terms what this means is your generator can be set to output 120/208V Wye 3 phase power (used in commercial 3 phase equipment), 120V single phase only power or 120/240V split phase (often also called single phase) used in household electrical connections. On the generator power connector you will find screw down split lugs marked L0,L1,L2,L3, in 3 phase mode all 4 connectors are used, in 120V only mode only 2 are used, and in household 120/240 split phase 3 are used (2 lines and a neutral). This is where things start to get confusing because these military generators use a different labeling system than residential 120/240 service with its L0 (neutral), L1 (line), and L2 (line). When the selector switch is in 120/240 mode and you are wanting to connect to a residential system (through a transfer switch for safety reasons) then generator L0 connects to house L0 as neutral, Generator L1 connects to House L1 (line ), then Generator L3 connects to house L2 (line) (note the is L3 to L2). This gives you 120 Volts measured from either line to neutral and 240V measured Line to Line. Measuring these line to line and line to neutral volts and amps is what the selector switch on the CONTROL PANEL does, for single phase operation you will only use some of the possible settings for measurement. At this point you may be asking why have both a 120V only and a 120/240 single phase setting on the voltage selector switch, the answer is in 120V only mode you get access to the full output of the generator, in 120/240V mode the output is split into 2 halves with half the output going to each line output and the return coming back through the neutral, in this mode it is more important to balance your loads and so you never draw more than half the total output out of either line (again back to the use of that meter selector switch on the control panel).


Ike

p.s. another important question when wiring a generator up to a home system is the ground bonding of the neutral connection all the references in the TM will talk about grounding L0 (neutral) to the frame and to a ground rod at the generator for stand alone operation. When used with a transfer switch it may be necessary to unbond L0 at the generator from the frame, or use a transfer switch that has a switched neutral if the MEP003 will not run unbonded. The important thing here is that your neutral is only bonded to ground in 1 place (this is usually at the service entrance for a home) this is a point where you should talk over your plans with your local electrical inspector or other electrical professional as code requirements vary from region to region.
THE "PS" here is important. When you connect a generator to a home via a transfer switch, typically only the two hot lines get transferred from grid to generator or vice versa. The neutral is still connected from generator to panel and to the grid. Since this neutral is already BONDED (i.e. tied to ground) in ONE (and only one) place, you should NOT bond your L0 neutral at generator to the frame and to the grounding rod. You can and should ground the generator frame to a grounding rod via the stud on the frame, but DO NOT bond the L0 neutral to the frame (which is grounded via the grounding rod at the generator).

The key is to understand how your transfer switch works. Does it only transfer the hot load lines (typically two hot lines) or does it transfer both the two hot lines and neutral. In this latter case, you would bond L0 to frame and to the rod at the generator set. Comments welcome as this is the tricky bit where an electrician is worth the $$$.
 

Scoobyshep

Active member
334
239
43
Location
Florida
If you are unsure how to hook to a home safely let me know. I can guide you in the right way of doing it.

Sent from my SM-G950U using Tapatalk
 

bones1

Member
854
3
18
Location
Southern Maryland
I set mine up about 5 years ago and I think I followed this or a similar thread somewhere. I just went out and looked at the generator and I have the neutral wire loose and taped off and it's in the shop so no ground rod attached. Never did. have that. I have a 4 wire #6 100 ft so cable going to the house Generac panel. It's one of those all in one 200 amp panels with a motor in the center that switches to backup power when working with Generac home standby models. It won't sense with the Mep-003 set. So neutral taped off and no ground rod am I correct?. Here is the panel https://www.electricgeneratorsdirec...dfppYd4ty4-o7brHQTsBY80CdukxECrhoC4yMQAvD_BwE

installation wiring pdf https://www.electricgeneratorsdirect.com/manuals/5449manual.pdf

I don't think it switches neutrals, maybe a pro could look. Edit. It does not switch neutrals.
 
Last edited:

derf

Member
924
8
18
Location
LA
For your house you want 4 wires. Two hot, one neutral, one ground. In general the neutral and ground go to the same place but the neutral is designed to carry loads and the ground is not.
Voltage between the two hot wires should be 220-240V and that will run 220V things.
Voltage between either hot wire and neutral should be 110-120V and that will run 120V things.
You need to figure out exactly what is connected to what. Pics would help but an electrician or very wise friend might be in order here.
 

derf

Member
924
8
18
Location
LA
Also, the Generac switch you linked to only has a 125 Amp switch. So, you will not be able to run everything you would normally run on your 200 Amp service. The generator may be able to power everything but 125 is only 62.5% or 200. This means you may not be able to run your central AC and electric stove and electric oven and electric dryer all at the same time like you can on regular 200 Amp service.
 

bones1

Member
854
3
18
Location
Southern Maryland
Correct. Appliances are gas and ac/ heat units are mini splits in parts of the house. I only am concerned with running the well and mini splits and tv computer, fridges and small stuff. Only 2 people live here so we're good with 125 A. And thanks for looking. I got it with the Mep003 's output in mind.
 

derf

Member
924
8
18
Location
LA
Sounds like you are on the right track. But, from where I sit you still need that neutral, if you don't have it. That panel allows the service to power everything and the generator to power everything below the transfer switch, which seems like a good setup if everything is wired correctly. Find out where your four wires go. You'll probably find two hots and a neutral and a ground that may terminate somewhere other than where your stray, taped off neutral wire is. From looking at the manual it seems like you need the "15 Amp sensing breaker" to be hooked up somehow and when it sees no service power and correct generator power it should switch into generator mode.
Was this system installed and tested, and now you're having trouble or was it ever tested and working correctly? Or, is this the first time you've tried to use it and it's not working?
 

bones1

Member
854
3
18
Location
Southern Maryland
Sounds like you are on the right track. But, from where I sit you still need that neutral, if you don't have it. That panel allows the service to power everything and the generator to power everything below the transfer switch, which seems like a good setup if everything is wired correctly. Find out where your four wires go. You'll probably find two hots and a neutral and a ground that may terminate somewhere other than where your stray, taped off neutral wire is. From looking at the manual it seems like you need the "15 Amp sensing breaker" to be hooked up somehow and when it sees no service power and correct generator power it should switch into generator mode.
Was this system installed and tested, and now you're having trouble or was it ever tested and working correctly? Or, is this the first time you've tried to use it and it's not working?
[/QUOTE
The electrician installed the panel, I got it inspected and it has never been tested with a generator. I am looking to do that now. It's been 5 years and I want to check the wiring from house to generator but I believe it is correct at the generator with the neutral to ground connection disconnected and taped off. I will double-check today and see if I did in fact do that. The utility power has not gone out once in 5 years since I bought the generator. The utility company upgraded the street to underground.
 
Last edited:

Coug

Well-known member
904
425
63
Location
Olympia/WA
So to answer the most recent few posts,

I set mine up about 5 years ago and I think I followed this or a similar thread somewhere. I just went out and looked at the generator and I have the neutral wire loose and taped off and it's in the shop so no ground rod attached. Never did. have that. I have a 4 wire #6 100 ft so cable going to the house Generac panel. It's one of those all in one 200 amp panels with a motor in the center that switches to backup power when working with Generac home standby models. It won't sense with the Mep-003 set. So neutral taped off and no ground rod am I correct?. Here is the panel https://www.electricgeneratorsdirec...dfppYd4ty4-o7brHQTsBY80CdukxECrhoC4yMQAvD_BwE

installation wiring pdf https://www.electricgeneratorsdirect.com/manuals/5449manual.pdf

I don't think it switches neutrals, maybe a pro could look. Edit. It does not switch neutrals.

I just want to ask for clarification. When you say you "have the neutral taped off" do you mean the neutral wire going from generator to breaker panel, or do you mean the wire/bar between the neutral lug and the ground lug? If the one between neutral and ground, then you're good. You shouldn't need/have a ground rod on the generator because there can be a voltage differential on the ground path between the two ground rods that can mess things up. The older NEC code said to ground generators, but the newer ones say not to if it's tied into the house's ground system.

No, neutrals are not switched by the transfer switch, because they should be permanently wired into the system. If it isn't connected to the neutral buss bar, then you have no 120V circuits, or they will be completing their path using a 120V circuit from the other leg, which means you're going to be putting 240V through it. If all the loads are balanced perfectly this won't be an issue, but that's extremely unlikely. Either this or they will be completing it on the ground path instead, which isn't a good thing, as the purpose of ground is more like an emergency exit path for electricity, it should NEVER have live current.

By any chance did the installer also run any smaller wires in with the #6 cable? (on a Generac standby there should be 3 more wires if newer than 2008 ) If so you could probably rig up a switch (like a light switch) to tell the transfer panel to operate and transfer to generator power (or you could do it with a 12V battery with trickle charge or some other method of a constant 12V power source)

Sounds like you are on the right track. But, from where I sit you still need that neutral, if you don't have it. That panel allows the service to power everything and the generator to power everything below the transfer switch, which seems like a good setup if everything is wired correctly. Find out where your four wires go. You'll probably find two hots and a neutral and a ground that may terminate somewhere other than where your stray, taped off neutral wire is. From looking at the manual it seems like you need the "15 Amp sensing breaker" to be hooked up somehow and when it sees no service power and correct generator power it should switch into generator mode.
Was this system installed and tested, and now you're having trouble or was it ever tested and working correctly? Or, is this the first time you've tried to use it and it's not working?

This is a dumb transfer switch, like all of Generac's switches. Dumb in this case meaning that the transfer switch does not control/initiate the transfer process. What happens is there is a 12V circuit coming from the generator that is always live. When the generator is up to speed and wants the switch to transfer, it grounds out the other end of that wire to complete the circuit, which allows the transfer switch to do it's thing (in this case rotate a knob that disables one breaker and then enables the other, it's ALWAYS break before make on these residential type switches)

So that "sensing breaker" is for power to the generator controller to see what utility power is doing (should be a dual pole breaker, so 240 volt, connected to N1 and N2). There should also be a 15 amp 120v breaker that is on the transferred portion of the panel that goes to the generator to keep the battery charged up if this were a normal Generac standby from within the last 8-10 years. if it's from before about 2008 they used a lot of individual components (auto voltage regulator, transformer, control board, battery charge board), and from 2008-2012 or so they did a few different things (none of this is actually relevant to the current topic, but thought I'd share anyway)


(I might not know as much about the MEP series generators as a lot of the guys here, but I AM a Guardian level Generac Certified Repair Tech (just means commercial level, 150KW and below) so I can at least help out on things like this ;) )
 

bones1

Member
854
3
18
Location
Southern Maryland
The electrician installed the panel, I got it inspected and it has never been tested with a generator. I am looking to do that now. It's been 5 years and I want to check the wiring from house to generator but I believe it is correct at the generator with the neutral to ground connection disconnected and taped off at the generator. I will double-check today and see if I did in fact do that. The utility power has not gone out once in 5 years since I bought the generator. The utility company upgraded the street to underground. Neither the electrician nor the inspector had never seen this type of panel so they weren't much help with how it worked. I ran the 3 or more smaller wires myself, they are deadheaded in the panel and would like more information on how to use/ connect a switch to operate the Generac panel motor, I've looked for information online to do this for years as well and you are the first with any information on it. Thank You sir.
 

Scoobyshep

Active member
334
239
43
Location
Florida
So to answer the most recent few posts,




I just want to ask for clarification. When you say you "have the neutral taped off" do you mean the neutral wire going from generator to breaker panel, or do you mean the wire/bar between the neutral lug and the ground lug? If the one between neutral and ground, then you're good. You shouldn't need/have a ground rod on the generator because there can be a voltage differential on the ground path between the two ground rods that can mess things up. The older NEC code said to ground generators, but the newer ones say not to if it's tied into the house's ground system.

No, neutrals are not switched by the transfer switch, because they should be permanently wired into the system. If it isn't connected to the neutral buss bar, then you have no 120V circuits, or they will be completing their path using a 120V circuit from the other leg, which means you're going to be putting 240V through it. If all the loads are balanced perfectly this won't be an issue, but that's extremely unlikely. Either this or they will be completing it on the ground path instead, which isn't a good thing, as the purpose of ground is more like an emergency exit path for electricity, it should NEVER have live current.

By any chance did the installer also run any smaller wires in with the #6 cable? (on a Generac standby there should be 3 more wires if newer than 2008 ) If so you could probably rig up a switch (like a light switch) to tell the transfer panel to operate and transfer to generator power (or you could do it with a 12V battery with trickle charge or some other method of a constant 12V power source)




This is a dumb transfer switch, like all of Generac's switches. Dumb in this case meaning that the transfer switch does not control/initiate the transfer process. What happens is there is a 12V circuit coming from the generator that is always live. When the generator is up to speed and wants the switch to transfer, it grounds out the other end of that wire to complete the circuit, which allows the transfer switch to do it's thing (in this case rotate a knob that disables one breaker and then enables the other, it's ALWAYS break before make on these residential type switches)

So that "sensing breaker" is for power to the generator controller to see what utility power is doing (should be a dual pole breaker, so 240 volt, connected to N1 and N2). There should also be a 15 amp 120v breaker that is on the transferred portion of the panel that goes to the generator to keep the battery charged up if this were a normal Generac standby from within the last 8-10 years. if it's from before about 2008 they used a lot of individual components (auto voltage regulator, transformer, control board, battery charge board), and from 2008-2012 or so they did a few different things (none of this is actually relevant to the current topic, but thought I'd share anyway)


(I might not know as much about the MEP series generators as a lot of the guys here, but I AM a Guardian level Generac Certified Repair Tech (just means commercial level, 150KW and below) so I can at least help out on things like this ;) )

MOST transfer switches dont switch the neutral, BUT there are some out there that do so it is very important to find out and setup your system accordingly.
 

Scoobyshep

Active member
334
239
43
Location
Florida
The electrician installed the panel, I got it inspected and it has never been tested with a generator. I am looking to do that now. It's been 5 years and I want to check the wiring from house to generator but I believe it is correct at the generator with the neutral to ground connection disconnected and taped off at the generator. I will double-check today and see if I did in fact do that. The utility power has not gone out once in 5 years since I bought the generator. The utility company upgraded the street to underground. Neither the electrician nor the inspector had never seen this type of panel so they weren't much help with how it worked. I ran the 3 or more smaller wires myself, they are deadheaded in the panel and would like more information on how to use/ connect a switch to operate the Generac panel motor, I've looked for information online to do this for years as well and you are the first with any information on it. Thank You sir.
Picture is worth 1000 words, (on windows 10 thats 64 kb(sorry early morning nerd humor)) I wired up a 200 amp generac panel for my 004, but all my controls are custom.
 

Coug

Well-known member
904
425
63
Location
Olympia/WA
MOST transfer switches dont switch the neutral, BUT there are some out there that do so it is very important to find out and setup your system accordingly.
This type does NOT switch neutrals.
It's basic operation is 2 double pole breakers directly across from each other in the panel next to the rotary switch. Power is fed to the lower portion of the panel through those breakers, with only one breaker being engaged at a time.
 

Scoobyshep

Active member
334
239
43
Location
Florida
This type does NOT switch neutrals.
It's basic operation is 2 double pole breakers directly across from each other in the panel next to the rotary switch. Power is fed to the lower portion of the panel through those breakers, with only one breaker being engaged at a time.
The point being, Unless you know exactly whats in at and whats been done it needs to be checked. Too many times have I come across an oddity because someone played Frankenstein.
 

Coug

Well-known member
904
425
63
Location
Olympia/WA
The electrician installed the panel, I got it inspected and it has never been tested with a generator. I am looking to do that now. It's been 5 years and I want to check the wiring from house to generator but I believe it is correct at the generator with the neutral to ground connection disconnected and taped off at the generator. I will double-check today and see if I did in fact do that. The utility power has not gone out once in 5 years since I bought the generator. The utility company upgraded the street to underground. Neither the electrician nor the inspector had never seen this type of panel so they weren't much help with how it worked. I ran the 3 or more smaller wires myself, they are deadheaded in the panel and would like more information on how to use/ connect a switch to operate the Generac panel motor, I've looked for information online to do this for years as well and you are the first with any information on it. Thank You sir.
For those three wires one is ground, one is live, and one is a switched ground. They should have 12V power to them.
Going by wire number (which you won't have, but Generac always does the same numbers)
Wire 0 is ground.
Wire 15B is 12V, and should always have power.
Wire 23 is the switched ground.
Where they connect to the rotary transfer switch you'll see
BAT - (Wire 0 )
BAT + (wire 15B)
XFER (wire 23)

The way it works is when the Gen is ready to take the load, the controller grounds out the XFER wire. This causes the switch to rotate 180 degrees, turning off the utility breaker and turning on the gen input breaker. When the XFER wire is ungrounded the rotary switch will turn back to it's starting position (another 180 degrees) disabling gen input and enabling the utility input.
In theory you could simply put something like a light switch (or other rocker switch with one side on and one side off) between the XFER wire and the ground wire, when the switch is turned to on the panel transfers to gen, when it's off it will rotate back. But that requires a 12V power source that will remain constant and charged up whether the gen is running or not.

Of course, to make it work manually you don't actually have to have the rotary switch powered at all. There is a bar between the utility and generator breakers, you just take those breakers and push them over to whatever power source you want to feed the panel from. Breakers are stiff so it takes a bit of force.

The manual method is probably a lot simpler at this point, if your generator isn't able to operate automatically then there is no reason to need the panel to switch automatically either. The ONLY real advantage to wiring it up to transfer with an electrical signal is if you are physically unable to operate the breakers due to poor health/low strength.


For everything to work automatically you would require some type of electronic control module at the generator end (I know someone makes them for the MEP 8XX series gens, don't know about the MEP-0XX gens)
 

bones1

Member
854
3
18
Location
Southern Maryland
Thank You for the information. I was just thinking of family members switching it over, i can do it easily. Also if I was to purchase a Generac small standby propane generator say a 17 kw to power this panel would that be overkill for this panel and would a 17k run ok on my 330 gal propane tank. It just powers the stove burners and very rarely the heat pump back up gas furnace. That way I could use the auto function I suppose. Just thinking out loud.
 

Scoobyshep

Active member
334
239
43
Location
Florida
003 is pretty easy to automate of thats a route you want to go.

Just something to think of

Sent from my SM-G973U using Tapatalk
 
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website like our supporting vendors. Their ads help keep Steel Soldiers going. Please consider disabling your ad blockers for the site. Thanks!

I've Disabled AdBlock
No Thanks