MEP-803A wiring into the home

[Bmxenbrett]

You may find that DB wire and digging a trench to be cheaper than soow wire. No rolling it up and storing it also. That also means it can be hardwired and someone not knowing to much can go and use the generator if your not around.

 

[stugpanzer]

That's a 5v drop under no load conditions. Once you put a load on that line, you will see an additional drop as current begins to flow.

Current and voltage are ALWAYS inversely proportional, meaning as current rises, voltage drops and vice versa.

Motors of any type will not like it if it goes too low. A motor cannot tell if it is being under voltage or physically over loaded torque wise, the result is the same which is excessive current draw and the production of heat.....sometimes lots of it and if it stalls, it will burn up.

If you cheap out on the main feed, you are just begging for problems further down the line. It would be hard to justify the "savings" buying a smaller conductor cable and then having an expensive repair bill on a heating system or other appliance.

Good points!

 

[stugpanzer]

You may find that DB wire and digging a trench to be cheaper than soow wire. No rolling it up and storing it also. That also means it can be hardwired and someone not knowing to much can go and use the generator if your not around.

Apologies to the OP as I feel I hijacked his thread but my application is 75' and I want to have the ability to use the same cord for home backup as well as elsewhere since my MEP is on a trailer. I don't relish the idea of carrying a 4/4 cord around and so when someone mentioned the Type W wire that is why I am digging into this subject!

Hard wiring for my home application would be difficult due to placement of the generator and the meter (which is near where the transfer switch would be).

 

[Farmitall]

Apologies to the OP as I feel I hijacked his thread but my application is 75' and I want to have the ability to use the same cord for home backup as well as elsewhere since my MEP is on a trailer. I don't relish the idea of carrying a 4/4 cord around and so when someone mentioned the Type W wire that is why I am digging into this subject!

Hard wiring for my home application would be difficult due to placement of the generator and the meter (which is near where the transfer switch would be).

A two wheel dolly is $39+- at Harbor Freight. Modify one to roll your cord up on and wheel it instead of carrying it.

 

[stugpanzer]

That's a 5v drop under no load conditions. Once you put a load on that line, you will see an additional drop as current begins to flow.

Current and voltage are ALWAYS inversely proportional, meaning as current rises, voltage drops and vice versa.

Motors of any type will not like it if it goes too low. A motor cannot tell if it is being under voltage or physically over loaded torque wise, the result is the same which is excessive current draw and the production of heat.....sometimes lots of it and if it stalls, it will burn up.

If you cheap out on the main feed, you are just begging for problems further down the line. It would be hard to justify the "savings" buying a smaller conductor cable and then having an expensive repair bill on a heating system or other appliance.

I do have a question on this. I read somewhere that NEMA codes call for motors to be able to function, with no issues at 90%. If I read that right and if true then that means a drop of 24 volts or 12 volts per leg on my AC Condenser (208/240 rated motor) should be able to continue running as low as 108 volts per leg or 216 volts. For my home backup I do have two AC Condensers and two furnace blowers of which I would only run one in the event of an outage. I have sump pumps as well. All other electronics that I might use have their own regulated power supply with more sensitive ones on their own UPS so they should be OK would think and then I have the usual electric stove (would limit it's use in an outage), microwave, lighting, etc. I don't believe I would ever draw what the MEP-803A can do under my circumstances but sure would appreciate any advice or input on my scenario. Do I understand NEMA standards on electric motors properly?

 

[stugpanzer]

A two wheel dolly is $39+- at Harbor Freight. Modify one to roll your cord up on and wheel it instead of carrying it.

Good idea! Are you suggesting I use THHN instead of cord to roll it up and store?

 

[Farmitall]

Good idea! Are you suggesting I use THHN instead of cord to roll it up and store?

No, THHN is made to be put into(cabled)into some type of conduit or jacket for protection, it is not for use as exposed conductors.

If you use THHN you must protect it. It has poor UV protection if any and the outer coating will shed. Its also quite fragile and will not take repeated rolling and unrolling like SO type cables with rubber insulation and fine strand conductors.

 

[stugpanzer]

No, THHN is made to be put into(cabled)into some type of conduit or jacket for protection, it is not for use as exposed conductors.

If you use THHN you must protect it. It has poor UV protection if any and the outer coating will shed. Its also quite fragile and will not take repeated rolling and unrolling like SO type cables with rubber insulation and fine strand conductors.

I thought so but was just clarifying!

 

[DieselAddict]

Your calculation is correct. As already pointed out that lowering the voltage will cause more heat rise in the motor. Excess heat shortens equipment life. I doubt any of us here could say by how much.

Where you can its advisable to keep the voltages more on the high side of the standard. If cost is not an issue I always go a size bigger than I need on the wire.

 

[Farmitall]

I do have a question on this. I read somewhere that NEMA codes call for motors to be able to function, with no issues at 90%. If I read that right and if true then that means a drop of 24 volts or 12 volts per leg on my AC Condenser (208/240 rated motor) should be able to continue running as low as 108 volts per leg or 216 volts. For my home backup I do have two AC Condensers and two furnace blowers of which I would only run one in the event of an outage. I have sump pumps as well. All other electronics that I might use have their own regulated power supply with more sensitive ones on their own UPS so they should be OK would think and then I have the usual electric stove (would limit it's use in an outage), microwave, lighting, etc. I don't believe I would ever draw what the MEP-803A can do under my circumstances but sure would appreciate any advice or input on my scenario. Do I understand NEMA standards on electric motors properly?

Your loads would be additive. If one appliance starts and runs drawing current and creating a voltage drop, then another kicks in and draws more current and creates more voltage drop, then another, and another the end result could be catastrophic if your wire size feeding the devices is too small.

You need to consider total current requirement and size the feed for the distance to the load to eliminate voltage drop. And its never a good idea to operate on the edge of capacities.

 

[Hard Head]

You would not be happy with low voltage being supplied to your home from the power company! Buy a larger conductor not a smaller one just because the insulator can take more heat! Treat your transmission circuit as critical. Every circuit you feed in the building also has a loss! Don't buy a cable to heat and rob your system of power. Low voltage damages motors due to increased amperage. Free EE advise.

 

[jaxbill]

You may find that DB wire and digging a trench to be cheaper than soow wire. No rolling it up and storing it also. That also means it can be hardwired and someone not knowing to much can go and use the generator if your not around.

I'm beginning to reach this conclusion. Honestly, I could probably rent a trenching machine for 4 hours and still save money compared to buying the right type of portable cable. I need to go back to the drawing board.

 

[Farmitall]

You would not be happy with low voltage being supplied to your home from the power company! Buy a larger conductor not a smaller one just because the insulator can take more heat! Treat your transmission circuit as critical. Every circuit you feed in the building also has a loss! Don't buy a cable to heat and rob your system of power. Low voltage damages motors due to increased amperage. Free EE advise.

Exactly!

 

[Hard Head]

Don't forget to call 811 before you dig!

 

[Bmxenbrett]

You may find that DB wire and digging a trench to be cheaper than soow wire. No rolling it up and storing it also. That also means it can be hardwired and someone not knowing to much can go and use the generator if your not around.

 

[DeadParrot]

Another thing to consider before trying to cut a corner to save money is tolerances. Motors, and other gizmos, have an acceptable voltage range in part to cover manufacturing variations. What ever the motor is spinning also has mfg variations. If both motor and load variations are such that the load is larger then expected and the motor is less efficient then expected, your current draw is already larger then expected. As long as everything meets specified tolerances, you are covered.

Now add in voltage drop from your emergency cable. The out of spec line just got closer.
Have you had that voltage meter on your generator certified? 5% tolerance in electronics is usually considered good. So that 120V indicated on your meter might be 126v or 114v. If the gen output is 114v at the generator lugs, what will it be at the transfer switch, at the motor input?

If all of your tolerance variations happen to shift in the same way, bad stuff could be the result.

 

[69birdman]

Here's what I did,
I wanted to keep it mobile so I mounted it to a 1500lb Axel 4x8 trailer. I park it 25' from power end of house, which has no windows. I used 30' of #6 SOOW with 50amp connectors & receipticles on unit and house. I can pull an old stove out of a shed ,plug it right in and give it an exercise ,whenever l want. 1' of #6 THHN from lug to output box then 7' of #6 THHN from input box to 50amp breaker.

 

[jaxbill]

Here's what I did,
I wanted to keep it mobile so I mounted it to a 1500lb Axel 4x8 trailer. I park it 25' from power end of house, which has no windows. I used 30' of #6 SOOW with 50amp connectors & receipticles on unit and house. I can pull an old stove out of a shed ,plug it right in and give it an exercise ,whenever l want. 1' of #6 THHN from lug to output box then 7' of #6 THHN from input box to 50amp breaker.

I like that setup a lot. I don't have a great way to move the trailer. I wish it were light enough to use a trailer dolly but I've been told it might be too heavy.

 

[Guyfang]

Your loads would be additive. If one appliance starts and runs drawing current and creating a voltage drop, then another kicks in and draws more current and creates more voltage drop, then another, and another the end result could be catastrophic if your wire size feeding the devices is too small.

You need to consider total current requirement and size the feed for the distance to the load to eliminate voltage drop. And its never a good idea to operate on the edge of capacities.

I don't post much in this arena. Its not what I know best. Too many other smart guys out there, so I just don't do it.

So, why am I here? Well, I follow everything generator wise, just to be able to do just this. At the end of the day, the whole thing rotates around You need to consider total current requirement. Everyone repeats it, over and over again, but not everyone "Gets it".

Everything about a house hook up hinges on this fact. Everything. Its the very first thing anyone tosses out in these threads. You simply can not figure gen set size, wire size AND length, hook up gear, safety gear and on and on, until you figure TOTAL current requirement. And then toss on a SAFETY SWAG!!! As has been mentioned, its not good to operate on the edge of the envelope.

Why don't you guys set down and write something for new guys. A guide to this many legged animal, "House Hook Up made simple, 101".

 

[jaxbill]

I agree. That's why I started this thread trying to validate the need for 60A connectors (to get the most out of the 803) and validate the need to up-size the wiring gauge to account for longer distances. I don't think anyone is trying to cut corners or eliminate a safety margin.

Past threads are split on the opinion for some of these decisions or just didn't cover my circumstance. I never found a sticky FAQ type thread like you're suggesting and that would be a good idea.