MEP803A Total Output Amps

Yea....getting my 803 in a couple of days. Sitting on a pallet in Tampa. Was doing some calculations and can see that 10kw is not a safe output figure. Some of these can go to 14kw and run all day long. This begs the question that at 14kw 240VAC means a feed output of 58Amps. Much more than the rated output of 51 Amps given as the standard output at .8 pf. While at 12.5kw @240VAC is 52A and a 220V is 56.8A

When tying into the house, shouldn't you use a 60A dual pole circuit breaker for power into the panel after interlock placement?

Why wouldn't you want to use the full output if the genset runs with no issues?

It depends on what you want to spend on connectors, IF you're even worried about the ratings for the connectors/plugs/inlets. Most people say the 50A stuff is rated for far higher than 50A. For 50 A, I think you can do non-twist lock / straight (RV style) or CS6365 flanged locking style but it costs more.

Above 50A gets expensive because this puts you into the pin & sleeve variety connectors. (I think someone makes a non twist lock 60A but I wouldn't use something that could come loose)

Elecdirect sells the cheapest new pin & sleeve components for 60A. You can get used Hubbell on ebay. I hard wired one end of Type W 6 AWG cable (rated @ 87 A) into the existing hole in the MEP. I put the Elecdirect female pin and sleeve plug on the other end. I have the corresponding inlet on the wall. It's IP67 watertight and locks in nicely. FWIW - the pin and sleeve stuff is much larger than I thought but seems heavy duty. It still cost a lot more (probably double compared to 50A parts) but I wanted it rated for the current I could draw, wanted twist lock, and wanted the watertight rating.

I have a 60 A breaker to protect that wiring because as you say, the breaker cost isn't that big of a deal. Overall, I don't think breaker costs increases much until you get to 70 A.

How much continuous load do you expect to put on the generator?

DieselAddict said:

How much continuous load do you expect to put on the generator?

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Every last watt I can safely squeeze out of it. Granted it won't be 100% power 100% of the time but even with load management, there will be times when every watt is needed.

gatorbob said:

It depends on what you want to spend on connectors, IF you're even worried about the ratings for the connectors/plugs/inlets. Most people say the 50A stuff is rated for far higher than 50A. For 50 A, I think you can do non-twist lock / straight (RV style) or CS6365 flanged locking style but it costs more.

Above 50A gets expensive because this puts you into the pin & sleeve variety connectors. (I think someone makes a non twist lock 60A but I wouldn't use something that could come loose)

Elecdirect sells the cheapest new pin & sleeve components for 60A. You can get used Hubbell on ebay. I hard wired one end of Type W 6 AWG cable (rated @ 87 A) into the existing hole in the MEP. I put the Elecdirect female pin and sleeve plug on the other end. I have the corresponding inlet on the wall. It's IP67 watertight and locks in nicely. FWIW - the pin and sleeve stuff is much larger than I thought but seems heavy duty. It still cost a lot more (probably double compared to 50A parts) but I wanted it rated for the current I could draw, wanted twist lock, and wanted the watertight rating.

I have a 60 A breaker to protect that wiring because as you say, the breaker cost isn't that big of a deal. Overall, I don't think breaker costs increases much until you get to 70 A.

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Yeah.....the connectors. They do cost so I'm thinking direct wire from genset to panel. No connectors needed, right from the load terminals to the panel breakers and bound N G strips. When the breakers are occ, I can still load the genset at the L terminals.

USAMilRet said:

Every last watt I can safely squeeze out of it. Granted it won't be 100% power 100% of the time but even with load management, there will be times when every watt is needed.

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Sounds like you didn’t buy enough generator to me.


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It's enough generator. I just want every available watt it can produce to be available. If I put 50A breakers in then I am potentially cutting 8 amps out of the power curve. That's almost 2000 watts.

Two thousand watts run a lot......

If you're not buying connectors, then it's simple in my view. I can't think of any expensive decisions to make regarding 50A vs. 60A.

I would buy the right type of cable (based on how it will or will not be protected) and the right gauge for the distance. If I were burying cable/conduit or running it in an attic in a house I owned, I would buy the largest gauge that is reasonable to work with and I can afford. You're only going to want to do it once. You might change generators one day. You can always terminate to a disconnect inside and/or outside so that your wiring into the panel or generator is smaller (more manageable but rated to support 60A).

Then buy the appropriate size breaker to protect the cable. If you use disconnects with breakers, you can lower the breaker size to match the output of the generator even if your cabling can support higher current. Since I had to transition from cable in a conduit to a portable Type W cable, I used a disconnect outside and it made the job easier for $50.

On your load size. I agree with and understand what you're saying about squeezing every watt out of it. You don't know what you don't know. I think of it as being prepared for the unexpected. If you find out your load needs to be 55 A for 2 hours even once, you don't want to have a 50 A breaker trip given that you own a generator that can output 58A. Especially if the cost difference is only a little more for the breaker and one gauge up in wire size.

USAMilRet said:

Every last watt I can safely squeeze out of it. Granted it won't be 100% power 100% of the time but even with load management, there will be times when every watt is needed.

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Hm. Interesting plan. Not one I generally recommend but interesting none the less.

Going the hard wired route is the best option. Fewer things to cause trouble.

USAMilRet said:

Two thousand watts run a lot......

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Yep. Since you're in FL and assuming you don't have natural gas, that extra 2000 watts might mean the ability to run your normal loads, the oven, maybe a burner, and not worrying about the AC compressor kicking on with full LRA in the middle of all that. Having the kitchen running might make someone happy while riding out a hurricane.

Edit: Like you said, I wouldn't run it at 125% for long periods of time.

I've wired 50amp receipticles/ 6ga awg @ the gen and house, and made a 30' cable with 6/4 SOOW 90c with 50amp straight blade male / cs twistlock female ends. I did go with a 60amp breaker in my interlock panel. My thought was if it were to have a startup surge a little over 50amps ,I wouldn't trip breaker.

Trying to get everything out of what I paid for. Assuming 12.5KW at standard load, that is 52.08 amps @ 240VAC So lets say that I am running a continuous 30A load for my house (lights, camera, action).....no seriously, pool pump (timer), salt water generator (timer), lights, refer, freezer, fans, stove, microwave, water heater (timer), computers (wife works from home) .... So at managed 30 amps continuous draw, the AC wants to kick in. With a soft start, the initial draw of a 3.5 ton unit is about 35 Amps start, running at 15 Amps or so. Now I am at 55 Amps constant draw. With a 50A breaker, trip goes the breaker requiring better load management. With a 60A breaker, no issues unless the generator does not want to put out 13.2kw which does not seem to be a problem with these generators.

So all in all, I just want to maximize the system and ensure that I can draw what the generator wants to put out safely (est @ 12.5kw to 13.5kw). Good question here, what is the surge capability of the MEP803A? I know it will depend on each different generator depending on the total safe sustainable output.

Bottom line - I can manage the loads to ensure that the generator is not "overtaxed" but I want to be able to squeeze everything out of it that I can safely.

As far as the 10KW vs 15KW generator, 15KW is overkill and I would be burning fuel for power that I won't use. With proper load management, I can run my entire household on the 10KW generator. I could do it on a 7.5KW generator but that would require a lot more load management and the sacrifice of some things that I am not willing to give up if I do not have to.

Now, to deal with the pesky neighbors with their extension cords........

I went the same way others have suggested. 50 amp RV connections with 6 ga cable and a 60 amp breaker on an interlock. So far so good. House is all electric with well and 3.5 ton AC/Heat Pump. I do some load management but sometimes I wonder if it's necessary. I'd rather not test to the limit of tripping the unit though.

Load banking has been done monthly with a resistive load. I usually hit it with 52 amps for a while then run it for a couple of hours at 40 amps. I have run it for 8 to 12 hours straight during an outage and baked cookies in the electric range while watching TV in a cool air conditioned house.

Your results may vary.

I'm going the hard wire route also. But I got a deal on some 1 ga wire to go the 40 feet between the generator and the new (manual transfer switch) main panel, the breaker is still only 60 amps per leg to protect the generator input to the house. The wire was about $150 cheaper than using new 4 ga wire, and only a piddling difference with 6 ga. 6 ga vs 1 ga for the same money, I'll go with the bigger wire!

How much overhead in capacity your machine has is something you'll need to test to determine. Where you'll see issues is with starting inductive loads when you are running at say +60% power output. That extra output over 100% can be utilized if you are gentle with load shifts. Assuming you can start your heatpump with the TOP 35a of capacity may not work reliably. Testing will be important to see how much load management is necessary.

Don't think I'll be using the heat pump function much. Maybe 3 nights last year but there is the odd year like when we got 10 or so consecutive nights of sub freezing temps. They say the farmers pulled over 11 millions gallons daily out of the ground to protect the crops. Local wells went dry and sink holes abounded in the eastern part of the county.

But if necessary, I can kill everything and use the heat system and it will only draw 7.5KW for the heating elements. Those have never kicked in so far.

I have to measure the distance and decide where I want to put the generator. I have two locations picked out but one is 35 feet farther than the other is.

I think we're talking about the heat pump compressor for regular AC and regular heat mode. It's a question of how much extra headroom you need to start the compressor whether its in cool or heat mode. I don't think the LRA is any different for cool or heat. Just the direction changes. The scenario Chris brings up is my biggest concern. Like he said, let's say I am at 60% power output and then the heat pump compressor wants to start. With a LRA well over 100 A, what will happen? This starts the whole debate over hard start vs. soft start kits vs. doing nothing.

Make sure you kill both heat strip control connections if you're running in freezing temps. The thermostat control wire and the control wire to the condenser's defrost board. I read someone disabled their "aux" heat on the thermostat but the totally independent defrost cycle caught them by surprise. I think disconnecting the control wires from the air handler is easiest. Of course, you'll have some cold air blowing in the house when the defrost cycle begins because the condenser will run the refrigerant in the opposite direction.

At 52A instead of 50A the breaker isn't going to trip for some time. It's only 104% of load. It's not a binary device, there's some play.

The curve for a SquareD QO puts the trip point for 125% of load at between 150 and 800 seconds. And it's a logritmic scale where under 125% isn't guaranteed to trip, but may.

56A is 112%

I've got all 50A connectors and breakers. The generator has bogged down from overload before anything tripped...

USAMilRet said:

Yea....getting my 803 in a couple of days. Sitting on a pallet in Tampa. Was doing some calculations and can see that 10kw is not a safe output figure. Some of these can go to 14kw and run all day long. This begs the question that at 14kw 240VAC means a feed output of 58Amps. Much more than the rated output of 51 Amps given as the standard output at .8 pf. While at 12.5kw @240VAC is 52A and a 220V is 56.8A

When tying into the house, shouldn't you use a 60A dual pole circuit breaker for power into the panel after interlock placement?

Why wouldn't you want to use the full output if the genset runs with no issues?

Click to expand...

keep in mind if your going to bring the generator up near or st full load that you keep the output balanced load. An unbalanced load can cause a winding to overheat. Put your clamp on the neutral. You should see close to no amps for a good balance. Balanced load also improves fuel efficiency with inductive loads.

It's just a matter of not using the oven and microwave when the a/c is running. You may have to manage the load somewhat but not a big deal - may be overthinking it.
The 803 is a beast and very reliable.