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House wiring questions

43
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Location
Kenner Louisiana
Not getting a permit is one way to make sure it will pass inspection. :D

Just as a FYI for others reading the thread, saying its a portable generator doesn't get you out of the violation. If you have a MTS then its assumed you are also doing manual load management so its not an issue. If its an ATS the assumption is the generator could be subjected to the full connected load. Automatically connecting a source to a load its not able to handle is the problem.
I’m in the building stage now. Once it is wired I will determine if load shedding is needed. According to my calculations and using soft starts on my AC I may only need my pool equipment to be disabled during running. Thanks for all the info.


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43
49
18
Location
Kenner Louisiana
Any views on this wiring


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Scoobyshep

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I’m in the building stage now. Once it is wired I will determine if load shedding is needed. According to my calculations and using soft starts on my AC I may only need my pool equipment to be disabled during running. Thanks for all the info.


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Active load management, use it to inhibit large loads pool ac water heater etc.

Another possibility is to set a sub panel for critical loads.

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DieselAddict

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I'm in the planning stage of a new house now. I'm going to be using a combination of utility power and solar power with generator backup. Since its a clean slate project its not expensive to put in two load centers. One is for all the "critical" loads and the other is for any regular loads. Fridge, lights, entertainment, water, etc will be on the critical loads panel. Dryer, water heater, oven, (big power stuff) etc will be on the normal utility panel. Since the solar is sized for the critical loads there is no issue with using the inverters internal transfer switch to bring in utility power as needed. I'm putting on an external computer controlled disconnect to remove utility power from the inverter in case I want to do that for any reason BUT the inverter also has a generator input and it will start a connected generator in case the batteries/solar is not keeping up during a utility outage.

This may sound on the surface complicated but its actually a lot less complicated if you aren't having to deal with existing systems. Gives you some good flexibility.
 

frank8003

In Memorial
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Follows is an old Florida powerplant guy comment.
Yes, I know opinions are like those holes people speak of derogatorily.

Gee, anything computer controlled would not work here.
Puters fault due to lightning ingress to ground. Very common, very difficult to ground here. Lightning just eats its way backwards to the equipment, like 20K to 200K amps, eats stuff.
You just make sure that whatever you do then do not harm the people down the line that are trying to put all the other peoples' power back on. It is a grave responsibility.
Meet that necessity.
It must be a couple hundred amp air gap throwover, absolute disconnect on meter can side.
 

DieselAddict

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Any views on this wiring


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#3 wire is good for the load. At 100' you'll be well within the recommend voltage drop.

Have you compared the cost of the cable with installing conduit and THWN-2?
 

Coug

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So a generac ATS is controlled by the brain inside the generator. It's relatively dumb.
Without a generator capable of sending a 12V signal through the transfer relay, all you really have is a manual transfer switch with some extra wiring and electron
I just purchased a 97 mep -803a. I will be hard wiring it to a ATS for my 200a main panel. The generator will need 100 feet of cable to the ATS. These are my questions. Do I need a breaker at the generator location upstream of the ATS? If so what amp rating? What size wire do I need to run for this 100’ length to power the entire house 200a panel? And is there anything else I’m missing.
Thanks


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Not getting a permit. It’s a portable generator. This genset will run my entire house with soft starts on my 3 AC units.


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These two things (highlighted and underlined above) are mutually exclusive.
Once it is hard wired to anything, it is no longer a portable generator. The only way to retain portable generator status is if you have all your load wires connected through some type of plug or quick disconnect.
Even if you were to have it on a trailer or something like that, I doubt the local code inspector will let you get away with it (sometimes they will, but in my experience they ALWAYS default to whatever best covers their butt if something goes wrong)


The generator already has a breaker built in, so as long as the wiring is sized properly according to NEC for voltage drop and whatnot there shouldn't be an issue. If they aren't happy with the internal contactor in the genset, then you'll size the breaker according to the wire size and length of run, not about the amount of actual power being run. The breaker is there to protect the wiring from overheating and in case of a short. You are allowed to use a smaller breaker, but never a larger one that the wiring/voltage drop allows for according to code.


Don't forget you will also need to run the control wires along with the power cables to control the ATS from the generator autostart module, as well as whatever you're using to keep the batteries charged up.



Even with soft start on the AC and the generator physically capable of handling the load you have planned, most codes look for the max POSSIBLE load, not the actual load. That means that you will indeed be in violation with this generator unless you install it as a sub panel or add some type of load shedding to it.
 
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Coug

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I'm in the planning stage of a new house now. I'm going to be using a combination of utility power and solar power with generator backup. Since its a clean slate project its not expensive to put in two load centers. One is for all the "critical" loads and the other is for any regular loads. Fridge, lights, entertainment, water, etc will be on the critical loads panel. Dryer, water heater, oven, (big power stuff) etc will be on the normal utility panel. Since the solar is sized for the critical loads there is no issue with using the inverters internal transfer switch to bring in utility power as needed. I'm putting on an external computer controlled disconnect to remove utility power from the inverter in case I want to do that for any reason BUT the inverter also has a generator input and it will start a connected generator in case the batteries/solar is not keeping up during a utility outage.

This may sound on the surface complicated but its actually a lot less complicated if you aren't having to deal with existing systems. Gives you some good flexibility.
Just make sure the inverter system you use is capable of both grid intertie as well as stand alone operation. I've come across a few setups where the grid intertie inverter won't function at all without a signal from the grid. Usually a standby generator will also give it the necessary signal, but not always.

And yes, starting from scratch does make life simpler.
 

DieselAddict

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I already have the inverter. Its a Schneider XW6848. I've been running it on my current house for a couple of years now.
 
43
49
18
Location
Kenner Louisiana
So a generac ATS is controlled by the brain inside the generator. It's relatively dumb.
Without a generator capable of sending a 12V signal through the transfer relay, all you really have is a manual transfer switch with some extra wiring and electron



These two things (highlighted and underlined above) are mutually exclusive.
Once it is hard wired to anything, it is no longer a portable generator. The only way to retain portable generator status is if you have all your load wires connected through some type of plug or quick disconnect.
Even if you were to have it on a trailer or something like that, I doubt the local code inspector will let you get away with it (sometimes they will, but in my experience they ALWAYS default to whatever best covers their butt if something goes wrong)


The generator already has a breaker built in, so as long as the wiring is sized properly according to NEC for voltage drop and whatnot there shouldn't be an issue. If they aren't happy with the internal contactor in the genset, then you'll size the breaker according to the wire size and length of run, not about the amount of actual power being run. The breaker is there to protect the wiring from overheating and in case of a short. You are allowed to use a smaller breaker, but never a larger one that the wiring/voltage drop allows for according to code.


Don't forget you will also need to run the control wires along with the power cables to control the ATS from the generator autostart module, as well as whatever you're using to keep the batteries charged up.



Even with soft start on the AC and the generator physically capable of handling the load you have planned, most codes look for the max POSSIBLE load, not the actual load. That means that you will indeed be in violation with this generator unless you install it as a sub panel or add some type of load shedding to it.
Not sure what part of the county your in but down here, the inspection is no way like you speak. The guy ask for no documentation and just collects your money.


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Coug

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Not sure what part of the county your in but down here, the inspection is no way like you speak. The guy ask for no documentation and just collects your money.


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it varies city/country around here. Some areas don't care, others won't let you do anything without a permit and inspection, and they can get really pissy about things they don't understand. Stanby generators fall under that category for a lot of the inspectors around here.
 

Daybreak

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Howdy,
So far, by what you have stated. You are way in over your head.

You do not want to use a ATS with a 200 amp service and a MEP-803A generator.
ATS = automatic transfer switch
By standards, you would need a generator to fully support your 200 amp panel. That means a 200 amp output.
Load shedding = added breakers which drop when going on generator.

You should be looking for a breakout panel for which has your necessary breakers in it supported up to your generator output. (Mep-803A = 52 amps 120/240)

You need to walk back the thinking of a ATS. The Auto start stuff would work with a breakout panel, just not for a service entrance 200 amp.

Code is the code is the code.
Your insurance company would void any claim for non compliance.

A Manual Transfer Switch would work.
A service panel interlock kit. A 200amp transfer switch, a breakout panel.
A interlock kit would allow you to make use of your entire panel breakers.
 
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43
49
18
Location
Kenner Louisiana
Howdy,
So far, by what you have stated. You are way in over your head.

You can not use a ATS with a 200 amp service and a MEP-803A generator.
ATS = automatic transfer switch
By standards, you would need a generator to fully support your 200 amp panel. That means a 200 amp output.
Load shedding = added breakers which drop when going on generator.

You should be looking for a breakout panel for which has your necessary breakers in it supported up to your generator output. (Mep-803A = 52 amps 120/240)

You need to walk back the thinking of a ATS. The Auto start stuff would work with a breakout panel, just not for a service entrance 200 amp.

Code is the code is the code.
Your insurance company would void any claim for non compliance.

A Manual Transfer Switch would work.
A service panel interlock kit. A 200amp transfer switch, a breakout panel.
A interlock kit would allow you to make use of your entire panel breakers.
An ATS with load shedding is done on every whole house generator that is done around here. They spec out a 22kw a 200 amp ATS. So not Shure why you say I can’t do that with the MEP-803a???


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Daybreak

2 Star Admiral
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An ATS with load shedding is done on every whole house generator that is done around here. They spec out a 22kw a 200 amp ATS. So not Shure why you say I can’t do that with the MEP-803a???


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Howdy,

Sure, with a 22kw generator in place.
For a MEP-803A 10kw, not so much.
Cost prohibitive.
Each shedding breaker is not cheap. You will have to widdle your entire panel down to 10kw.

A generator break out box with only the necessary breakers could be done.

Have you priced out a 200 amp ATS? and one which has the ability for load shedding? and all the load shedding breakers your will need?
 
43
49
18
Location
Kenner Louisiana
Howdy,

Sure, with a 22kw generator in place.
For a MEP-803A 10kw, not so much.
Cost prohibitive.
Each shedding breaker is not cheap. You will have to widdle your entire panel down to 10kw.

A generator break out box with only the necessary breakers could be done.

Have you priced out a 200 amp ATS? and one which has the ability for load shedding? and all the load shedding breakers your will need?
I have a break out panel now in service for my gas standby. I’ve done the math and with soft starts on my ac units and load shedding i will stay in the constraints of the 803. And I’m not sure what cost prohibitive means to me. My house is all smart controlled(every light, pool equipment and ac units). I can control as needed. My neighbor has an 803 and runs his whole all electric house with no issues and his house is much bigger.


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LEOK

Active member
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Location
Gainesville/Fl
I think trying to use a MEP Is a bad idea, get new genset with line monitor controller like the Deep Sea 7200 it will drive the 200 Generac ATS. Plus give you lots of other capabilities. Get ground put in that comes in under 10 ohms and weld the rod connection. Adding Solar into the mix while on Generator adds complexity.
 

Coug

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So to my understanding that 200 amp transfer switch is required because the service to the house is rated at 200 amps. The generator size doesn't really matter as long as it's maximum possible output is LESS than the 200 amps the switch and panel are rated for.

The way the code works though is the generator has to be sized for the max possible load that can be placed on it according to the wiring in the panel. This would be if somehow every single appliance in the house was operating at the same time and had startup surge at the same time. The 803 might handle it for your load, it might not. What works out on paper might not work out in real life.


The article below has a lot of the NEC information regarding generator requirements. Most local jurisdictions will use the NEC (either the newest or one or two editions past) for their requirements.

 
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