# What size concrete pad would you use?



## Dargo

I traded my 65kw generator for a brand new Mas Power MEC45DSA (far right hand side generator but with a 200 gallon fuel tank) for my house.  I already have all the conduit in place and this automatic transfer switch installed ASCO 400 amp Service Rated NEMA 1 Automatic Switch by professional electricians.  

Basically, I know I _could_ install all of it myself, but I'd always be worried that if my home ever had a fire or something electrical related, I'd strongly prefer to have a professionally installed and code inspected installed unit.  That leads up to my real question; how much of a concrete pad does it need to sit on?  My electrician, although very knowledgable about my generator, has never installed the concrete pad for any of his customers.  We've decided that the pad needs to be a 6'X12' pad.  Then...., that's when the stories vary depending upon who you ask.  With the larger tank and filled with fuel, the generator has a reasonably small footprint but will weigh around 4300 pounds as installed.

I'm getting ready to go leave and get the lumber to make the form and the rebar.  Right now I'm looking at using 2X10's for my forms, giving me just over 8" of thickness for the pad.  I can't decide whether I should go with the mesh in it or not.  I'm also going to use a tile spade and dig a 'footer' just inside the forms along with generous use of rebar.  I'll still be under the 3 yard minimum load.  With the 'footers', I'm figuring around 2 yards of concrete.  I do have some eroded areas around the base of my bridge where I can have the other yard poured.  Literally, that last yard is costing me $4 because of the minimum charge for delivery.

I will have the generator sitting on 1/2" rubber that used to be surplus conveyor belt material in the coal mines.  Still, I have 4000 pounds of vibrating weight on the pad.  Oh, the conduits for the generator are in place and will actually come up inside the generator from under the pad.  From the outside, there will be no wires or conduit showing.  Should I go ahead and get the fiber anyway?  I don't have a lot of faith in it, but if it helps some, on this small pour, it may be worth it.  Thoughts?


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## bczoom

I wouldn't worry too much about the vibration.  Those units are pretty stable and have their own dampening system.  Your dimensions and thickness sound good to me.

_Now if I was plopping one of those in, besides having its own fuel tank, I'd probably plumb it into a bulk tank as well._


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## tiredretired

That's a lot of concrete there.  Should support that genset very well.


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## muleman RIP

Don't be in a hurry to set that weight on there. Two weeks min. and 3 is better. After that amount of time 4" with wire would support it. Fiber is overkill for weight that is not moving on and off the poured slab.


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## joec

We just removed and re poured a section of concrete here 20' x 30' that gets constant heavy truck from the large garbage truck to semi traffic. It is 4.5" thick of the highest rated PSI rating and no rebar. It replaced the exact same thing that has lasted 25 years of the constant pounding. So basically I would think once it is set it will be fairly stable. I don't see much of a need with out constant traffic of heavy vehicles to make it over a 4" pour using the pig fence if worried about it.


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## Dargo

muleman said:


> Don't be in a hurry to set that weight on there. Two weeks min. and 3 is better. After that amount of time 4" with wire would support it. Fiber is overkill for weight that is not moving on and off the poured slab.



For that size and weight generator, code calls for 6" 4000psi minimum.  I'm not a "minimum" kind of guy, so even 6" is out of the question for me.  Besides, I am having each step of the process inspected per my building permit for setting up this generator.

I guess I'm going with 8" with 1/2" rebar on 12" centers (on their little 2 1/2" stands) with the 1/4" wire matting over that with no mesh.  It isn't costing me $50 to do all that extra.  It would cost me thousands to go back and do it over.  Here in 'earthquake territory', the generator must be secured to the slab if it's sitting on it's own fuel tank.


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## tiredretired

Do it first class and it only hurts once.  Cut corners to save a few bucks and it will hurt many times.  Do it right!


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## BRGTold

I will have the generator sitting on 1/2" rubber that used to be surplus conveyor belt material in the coal mines.      If you think this is needed ..I would only place it under the Feet/Pads that the unit has for support..not under the entire unit..as to me it would seem it would hold moisture and Freeze flake/Rot concrete in the freeze thaw cycle.. Just a thought...


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## tommu56

As important than the thickness is the soil under it be sound.
The concrete has to have good drainage under it to prevent frost heave.
Compaction or not disturbing of the soil under it is important too.


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## Dargo

tommu56 said:


> As important than the thickness is the soil under it be sound.
> The concrete has to have good drainage under it to prevent frost heave.
> Compaction or not disturbing of the soil under it is important too.



Good point.  Fortunately, or unfortunately - depends on what you're doing, my soil is like concrete right now.  Even if the concrete truck was fully loaded with 11 yards (I thought they could only get 10 on a truck, but I have several tickets from where they had 11.1 or 11.2 yards on a truck - which did NOT make me happy when I said 6 yards MAX, since they were driving on my concrete driveway!), it would not even leave marks in the dirt.  I literally crushed the top portion of some form pins trying to get them driven into the ground today.

I have a few pieces of rebar to tie on tomorrow before the concrete gets here, but otherwise I'm ready; for better or for worse.  These one man projects seem to be getting harder for old man Dargo   It's just not nearly as fun as I remember digging in my rock hard clay soil.


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## Dargo

Oh yeah, does anyone else spray the inside of their forms with diesel fuel before pouring?  That's what I've done in the past and the forms come off easily and I don't have any pieces pop off of the slab.


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## muleman RIP

Pump up weed sprayer with diesel works like a charm. I can't quite believe they need that heavy of a slab for your genset. Even full of 200 gallons of fuel it would only weigh 3400 lbs.


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## grizzer

I usually dig down deeper & pour sand for a bed so the slab will float easier during freeze/thaw. The rubber belting might contribute a harmonic if the machine has it's own damping system already engineered for concrete.


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## Dargo

muleman said:


> Pump up weed sprayer with diesel works like a charm. I can't quite believe they need that heavy of a slab for your genset. Even full of 200 gallons of fuel it would only weigh 3400 lbs.



Company said with my larger tank, apparently weighs more, and an upgraded enclosure that the 'operating weight' of my generator full of fluids (antifreeze, oil, fuel etc.) would be right at 4300 pounds.  Right now it's on it's own tandem axle trailer.  We will use my excavator to lift it off the trailer and set it in place when the concrete is ready.  I'll have a somewhat small but very heavy duty trailer then.  My only trailer now is a big dual tandem pintle hitch rig.  A bit overkill to say the least to haul my 4wheeler etc.  More projects...just what I need.  Closing on another rental house Tuesday.  It's going to take some time to quickly get it ready to rent.

Oh, a little 1 gallon pump up sprayer is what I was going to use.  Perfect.  In the past it just seemed to make clean up easier and less adhesion of the concrete to the form.


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## Dargo

grizzer said:


> I usually dig down deeper & pour sand for a bed so the slab will float easier during freeze/thaw. The rubber belting might contribute a harmonic if the machine has it's own damping system already engineered for concrete.



It's dampening system is/was a trailer.  The stuff is 5/8" thick.  I figured 6 4"X4" pads; one on each corner and one in the middle on both sides.  Best places?  Electrician seems to think that would be fine.  He's somewhat lost on those sort of questions.  He knows the electrical part, but apparently my generator is more of a commercial/industrial unit whereas they install the little NG or LPG home units each week.  It did make me feel a bit better when he ordered one exactly like mine after calling the manufacturer to ask them a few questions.  He seemed really impressed with the gen head itself and the Deep Sea brand electronics that come with the unit.  If I needed to run 3 phase, all I have to do is flip a lever inside the machine.  It's already setup for that.  My electrician really liked the idea of having a single and 3 phase generator he could take to job sites.

I'll let everyone know how it works in a month or so.  I'm not going to rush the pad after waiting this long.  I'm told that my concrete will be at maximum strength in 27 days.  That could be pure bullshit, but I'll take their word for it.  It's what they do for a living and they have to have their end product tested to make sure it meets the psi rating quoted.  Oh, it has a 2nd conduit run to it to run the block heater and built in battery tender when I have utility power.  I guess that's probably a good idea.  Just seems to keep raising the cost of the unit.  When I first started, I thought I could get an entire system for what just the automatic transfer switch cost me.


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## muleman RIP

Concrete reaches 80% of strength after 21 days and total strength after 20 years. That was the old rule we always went by. Good deal on the block heater and battery tender. They never drop power on nice sunny days. It seems the colder and  nastier it is outside is when the bad outages occur. Hope you are up and running when the brownouts start.


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## BigAl RIP

Dargo said:


> I traded my 65kw generator for a brand new Mas Power MEC45DSA (far right hand side generator but with a 200 gallon fuel tank) for my house. I already have all the conduit in place and this automatic transfer switch installed ASCO 400 amp Service Rated NEMA 1 Automatic Switch by professional electricians.
> 
> We've decided that the pad needs to be a 6'X12' pad. QUOTE]
> 
> 
> 8" thick pad will be great . 6 sack mix with 1 1/2" rock a will get your PSI strength way up there . I would work with a "Slump test " under 4" . Be careful on adding to much water at the job site . It can dilute your PSI strength  Forget "Bonny fibers" and go with #3 rebar 12"O.C. both ways for a steel rebar mat . Wire tie at every cross . Lap your rebar @ 40 times the diamenterof the rebar . I would not go with 6x6#10 wire  mesh.
> *All concrete can crack* but rebar will give it structual strength where's wire mesh will not .
> Also fill or  sub base should be "virgin soil" or compacted fill @ 90 percent minimum .
> Cure and keep wet for 28 days to gain 80 percent maximum strenght . Vibation can cause lots of damage if used too early .We use carpet, wet down to keep the slab wet and let it cure slowly.
> 
> Better safe than sorry ... JMO


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## Dargo

The day *before* my electricians made the huge change in wiring to allow my generator take over during a power outage we got slammed with another *huge* voltage spike.    I lost the entire contents of 3 refrigerators, the refrigerators, 4 multi-stage A/C units, 2 large dehumidifiers in my safe room and lots more.  Granted, having backup power would not have helped.

However, now that I have 100% capability to run everything on standby power, is there any reasonable way that I can protect my home, and generator, from power surges.  The utility company has billions and a team of attorneys who tell me why they aren't at fault.  I'm not going to win there.  My insurance company, State Farm, lost *all* of my business when they screwed me royally the only time I turned in an insurance claim.  My real question is, is there any way I can reasonably be behind a power spike or lightning strike and be protected?  Hell, I had my Keurig coffee maker plugged into a blue GFCI outlet and it got toasted...along with the toaster. 

I've spent a huge amount to make sure I have power.  Now I need to see what I can do to be protected from these damn power spikes and, what seems just as bad, low voltage, hits?  I'm told my generator will kick in on low voltage and I'm covered there, but what about these spikes?  I'm at the end of the line and somewhat isolated.  Any ideas?


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## Melensdad

Do you have a whole house circuit breaker/surge protector on your electric box?


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## Dargo

No, not really.  It's a very complicated grouping of boxes and conduits, all to pass latest codes, that take up a huge area both inside and outside the house.  The only single place the power is all funneled from is my generator, and that's only if I'm running on generator power.  We pulled a full and complete 'slam' transfer to the generator with 4 A/C units hitting as well as 2 compressors and 3 welders all in the "on" position and the generator barely puffed when it took the load.  I almost wonder if the now 800 amp service I have at my property is more than is really available during peak times at the end of this run.  They've increased the size of wire and transformer twice to try to remedy the problem to no avail.

I'm trying to look and see if there is some sort of 'surge protector' that can at least be installed at the point where power enters the main house.  I don't know if that's possible or if it's economically feasible.  It cost a small fortunate, IMHO, to have all the large battery backup and high joule rated APC installed before my server, office computer and backup module.


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## EastTexFrank

Dargo, like you, I got tired of burning up fridges and freezers and losing everything in them as well as miscellaneous electrical stuff in the house every time there was a spike.  And, just like you, the electric company denied all responsibility for any of it.  However, when we were discussing it, they said that they could install a whole house surge suppressor for the installation fee, equipment fee and a few dollars on my monthly bill.  So for a few hundred dollars I had it done and haven't lost anything to a power surge in 7 years and we get them all the time.  We had 5 power blips just the other night during our 20 minute gully washer and before that would have almost guaranteed smoking something. 

So, the equipment is out there.  I don't know much about the equipment itself as I just told them, "Do it" and they did.


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## Dargo

Thanks, I'll  certainly try that route. Wife just told me our 2 year old stackable front loading washer and drier are fried. If I recall correctly, there goes another 3 grand or so and a half day wasted.


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## Melensdad

EastTexFrank said:


> . . . they said that they could install a whole house surge suppressor for the installation fee, equipment fee and a few dollars on my monthly bill. . .



Mine was installed after a couple fried computers and TV sets.  However mine was installed by a commercial electrician, rather than the power company.  Have not had a problem since.


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## bczoom

What was the cause of the electric spike?

I find it interesting that the power company isn't going to pay.  I encountered a spike once that toasted everything that was running at the time.  It took awhile to get to the right person/people at the power company, but they did pay.

I thought they had to guarantee the voltage +/- a few percent.  Spikes and brownouts are the power companies problem (and liability).


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## Dargo

Ah ha!  Found what I needed.  Installation this week.

Square D Surgebreaker

After talking to all the commercial electricians this last week, if anyone has any amount of expensive electronics in their home, I'd highly recommend having this installed.  I lost 2 refrigerators, 3 flat panel TV's, my coffee maker, a dryer and 3 dehumidifiers...that I've found so farIt's far, far less than you think.  (Hint: I paid more for my APC battery backup/surge protector unit for my computer in my office).


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## Dargo

Severe thunderstorm warnings, tornado watches, flash flood watches etc. are forecasted for us tonight.  Fortunately, after being back-ordered, my final piece of backup power and surge/lightning protection came in and my electricians installed my Square D "Whole House Surge Protector" earlier today.  I have 100 gallons of diesel in the 110 gallon tank, all has been load tested and the electrical inspector just left after giving me a final completion green tag for my generator and surge protection electrical work.

Now just wait, after our power *always* goes out, it won't go out tonight.  Oh well, that would probably be best.  I should finally be set for outages and heavy power spikes.  Power spikes have cost me about half as much as all my generator and surge protection equipment has.  Our power company has multiple law firms backing them where you're guaranteed to never get anything from them.  Anyway, here is the final piece of the puzzle (I hope).

Also pictured is my breaker box/transfer switch box area before whole house surge protector was installed and outside unit.  The grass has grown up around the outside unit now with a passion.  I waaaay over seeded it and put down plenty of fertilizer.  Now that we've gotten rain after having the driest summer on record, it needs mowing about 3 times per week!


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