MEP Power Distribution

[JR2980]

To all of you that are using MEP-802a's (or 002's or other gensets) without tying it directly to your house panel, how are you distributing the power off of the lugs on the genset?


I don't want to tie the genset into my house box - ideally, I'd like to have some kind of portable distribution panel that I can store in my garage with a coil of cable, then when I need it, take it out, connect the cable to the lugs on the genset, and plug things into the box in my garage as needed. I've got a small house, and wouldn't be looking to power everything, so running an extension cord here and there would work ok for me. My sump pump, freezer and a refrigerator are located in the garage, so they would be close to the distribution panel and easy to plug in and my gas furnace is in a utility room right off the garage, so I could plug it in as well if I needed to. I wont be running AC, and I can run extension cords in to the house to power lights and maybe a computer/TV if needed.

Just wondering how everyone else is handling use cases like this - 5KW seems low to tie it to a home panel, so I cant be the only one using it this way can I? Anyone have any recommendations?



Thanks!
JR

 

[cuad4u]

A quick way is to connect via a an electric clothes dryer receptacle and "back feed" the breaker panel. Most electric clothes dryers are on a minimum 30A circuit which is OK for a 002A. Use a length of 10 gauge cable with a plug that will mate to the clothes dryer receptacle. Make sure you cut off the main breaker and any un-needed breakers and any breakers that would exceed the generator's capacity before closing the main breaker on the generator.

 

[JR2980]

A quick way is to connect via a an electric clothes dryer receptacle and "back feed" the breaker panel. Most electric clothes dryers are on a minimum 30A circuit which is OK for a 002A. Use a length of 10 gauge cable with a plug that will mate to the clothes dryer receptacle. Make sure you cut off the main breaker and any un-needed breakers and any breakers that would exceed the generator's capacity before closing the main breaker on the generator.

Thanks for the input - I'm familiar with back-feeding the panel, but that violates the law in my state (and probably every state). I'd really like to stay legal.




JR

 

[Isaac-1]

I like to keep my MEP-002a rigged to be somewhat portable in case I need to loan it out to relatives during an extended outages, etc. Therefore I have a 120/240 L14-30 twistlock pigtail hooked to the output lugs, and a have a 30 amp 25 ft long drop cord with 4 20 amp push breaker protected outlets on it that plugs into the pigtail for mobile operation. Sort of like this one: https://nooutage.com/B104-DW.HTM except mine is double sided and molded plastic not metal box. For my 10KW MEP-003a I have a similar home made 100 amp distribution box made from a breaker box with outdoor outlets mounted around it with 50 ft of SO cord that I bought used off ebay for cheap. It works, but is a bit heavy to move around.

 

[JR2980]

I like to keep my MEP-002a rigged to be somewhat portable in case I need to loan it out to relatives during an extended outages, etc. Therefore I have a 120/240 L14-30 twistlock pigtail hooked to the output lugs, and a have a 30 amp 25 ft long drop cord with 4 20 amp push breaker protected outlets on it that plugs into the pigtail for mobile operation. Sort of like this one: https://nooutage.com/B104-DW.HTM except mine is double sided and molded plastic not metal box. For my 10KW MEP-003a I have a similar home made 100 amp distribution box made from a breaker box with outdoor outlets mounted around it with 50 ft of SO cord that I bought used off ebay for cheap. It works, but is a bit heavy to move around.

Thanks for the info!

I like the idea of the pigtail off of the lugs - more convenient than attaching to the lugs each time.

Could you post pictures of the portable one as well as the 100amp one when you get a chance?

With your setup, you could never actually use the full 5KW correct? (I'm trying to visualize, so correct me if I'm wrong) With a 30 amp plug, the most you could ever draw would be 3600W (at 120V). I'm guessing that you could hook up 2 30amp connections to the lugs to get the full amount as long as you were careful and didn't overload each leg right?





Thanks,
JR

 

[Isaac-1]

With this portable setup I could draw up to 4800 watts on the MEP-002a plus I could always plug into the front panel outlet for a few extra amps if needed, close enough to the rated output for my purposes, particularly if it was loaned out to someone with poor understanding of load management The generator is set to 120/240V single phase mode, and the L14-30 is a 120/240 connection, with a pair of 120V 20 amp breakers, so 2 standard 20 amp outlets (room to plug in 4 cords), one wired to each hot / neutral connection. So 2x20x120 = 4800 watts. Which is as you noted is still 6 amps short of the rated 26 amps at 120/240VAC. I also have a similar drop box setup on my 3KW MEP-016D with a metal outlet box with 4 outlets (a 20 amps and a 15 amp) that is not breaker protected, the MEP-016D is set up 120V only though.

 

[steelandcanvas]

Thanks for the input - I'm familiar with back-feeding the panel, but that violates the law in my state (and probably every state). I'd really like to stay legal.

JR

Good call JR...not only is Cuad4u's advice illegal, it's extremely dangerous to use electrical parts in a manner for which they were not intended.

 

[Keith_J]

I was given a 12 outlet box that was fed off 10 AWG 3 C SJOW service cord. Originally, it was for a Compaq computer server. It has two 15amp circuit breakers, one for each 6 NEMA 5-15 outlets (standard house 120 VAC outlets). It is all surge protected (line-neutral-ground).

It was only single leg but with a little rewiring, it is now 2-leg which reduces the load on the 10 gauge feeder line. Both circuit breakers work and they have been tested. It also has two 20 amp fuses for double protection.

I have it pigtailed for load terminals but a locking plug could always be installed.

 

[JR2980]

Thanks for all the input guys - keep 'em coming!

It seems that a home-built solution is the way to go, so I guess I'm going to need to start reading up on AC and 1/3 phase power. My background is DC, and while I had some AC primer training, its been a while and definitely not my strong suit.





JR

 

[Ratch]

If you're just going to build a box to hold outlets (either 110v/15a duplex, 30/50a dryer, 110v/20a, etc), the possibilities are endless and easy.

You could put a dryer plug on the side of the genset, build a mini-breaker panel box at the end of 100' of rubber-jacketed 10/4 with a dryer plug at the other end, and you're good to go.
You could put a mini breaker panel on the genset leading to a box with a dozen receptacles, then extension cord everything, etc.

While it's illegal to backfeed a panel, there's not really anything more unsafe about it if you're physically disconnected from the utility and using the properly rated breakers and wiring. Heck, the cheapest UL approved "transfer" switches are just backfeed breakers with a physical interlock to the main breaker. I could buy a retrofit to my 1973 main panel that's just a backfeed breaker with a metal obstructing tab on the lever, or a retrofit panel cover to add an interlock to my existing breakers. It's illegal because you could kill a utility worker by accidentally backfeeding the grid, not because it's a safety issue relative to the panel.
Some people will actually pull the meter from the meter pan before backfeeding as a way to be certain it's disconnected and provide a visual indication to utility crews (breaking the meter seal is also usually illegal, but I did it when I needed to replace a breaker panel, and the utility company was fine with that, came back and resealed it some time later).
I don't know where I heard it, maybe on this board, but I heard utility crews will not even service your neighborhood if they hear a genset running and can't tell if you have a transfer switch. That could be BS (no crew ever seemed to care or ask if I had a xfer switch when my MEP was loudly powering my house), but it makes the point that backfeeding is dangerous to utility crews.

Take that as you will... I personally neither endorse or oppose violating NEC by backfeeding through an unapproved panel... When you start playing with household voltages at capacities that can kill you, you're pretty much presuming you're going to be able to do things without creating large safety hazards, but the world still isn't made of nerf.
I've seen approved switches fail unsafely (granted, you could see the failure coming in the switch design and you'd wonder how it ever got approved). The right person can do it right for the rest of their life, the wrong person can do it right until it kills them or someone else. That's why there's code... But there's nothing inherently dangerous about backfeednig a disco'd panel.

 

[Isaac-1]

On the safety of backfeeding:

As I see it there are 2 big safety issues with the common dryer plug method:

1, the plug itself if live when the generator is running and it is a non-locking plug, meaning those prongs are live if anyone were to unplug it while the generator is running.

2, There is a potential of killing linemen (pole top transformers are bidirectional and will step up that few hundred volts up to a few thousand) if you ever mess up the sequence switching the breakers, this may not be a problem if you know what your doing and are alert. The big problems come in if you may not be there and a family member that does not know what they are doing tries to switch things, or perhaps you are not alert, have been awake for 3 days, etc.

On the topic of utility companies and servicing houses with running generators, you see a lot of variation on this topic, some utility companies require registration of transfer switches, and if they see a generator hooked to a house without one registered on file they will assume backfeeding is going on. So it is probably worth it to check with your local utility company. Some even have subsidy programs to help pay for transfer switches.

 

[JR2980]

Hey guys - I appreciate all the input so far.

I didnt mean to turn this into a back and forth on back-feeding with my response earlier. I know that backfeeding can be just as safe as anything else if done properly every time. The potential safety issues with backfeeding are a problem for me personally, but just as big are the potential legal issues. If you screw up even once and hurt someone, they (or their heirs) will own you; if you have a problem and your house burns down, you're screwed. Insurance will not pay if you're operating illegally, and if you hurt/kill someone, you'll end up facing charges and do time. For me, its just not a risk that I'm willing to take when there are some fairly straightforward ways to do it and stay legal.

Thanks for all the discussion, and keep the ideas coming......and if you have pics of the system you use, please post 'em; I'd like to see some of your setups.





Thanks!
JR

 

[Ratch]

Well yes, a live male plug is insanity... That's why genset plugs for the house are male, so the jumper is a safer female-to-female.

Sorry, I didn't mean to make it a backfeeding debate, either, although I guess I did.

 

[TucsonVTXF]

I would install an outlet for your RV on the outside of your house...

 

[captain]

dedicated and appropriate sized breaker in your panel with an interlock. The correct sized nm (or thhn with conduit) in the house to an outlet outside. SO cord from the gen to a twist lock or pin and sleeve plug. make sure to use 4 wires L1, L2, G and N. unbond ground and neutral at gen. This is not expensive on a 5kw or 10kw gen. At 15kw it gets costly and heavy.

 

[lonesouth]

I'm looking at building a breakout box to mount on my trailer. Currently planning to use a 24 circuit load center with 10 of the slots feeding 20 amp 120v receptacles, and additional slots feeding a 50amp 240v outlet and a 30amp 240v twist lock. That should pretty well cover all of connection options. One thing I have not figured out yet, is a box in which to house all of the outlets. Ideally this will be somewhat weather resistant, but I'm at a loss thus far to find something that fits that.

Also, I'm thinking about adding ammeters for each circuit to show to draw and to indicate that the outlet is hot.

 

[DieselAddict]

I'm looking at building a breakout box to mount on my trailer. Currently planning to use a 24 circuit load center with 10 of the slots feeding 20 amp 120v receptacles, and additional slots feeding a 50amp 240v outlet and a 30amp 240v twist lock. That should pretty well cover all of connection options. One thing I have not figured out yet, is a box in which to house all of the outlets. Ideally this will be somewhat weather resistant, but I'm at a loss thus far to find something that fits that.

Also, I'm thinking about adding ammeters for each circuit to show to draw and to indicate that the outlet is hot.

Hoffman boxes of sufficient sizes can be found second hand. They are pretty cheap used. Get one that is deep and mount lots of outlets inside. You make some generous sized holes in the bottom to accommodate cords with connectors on them. For the large outlets you mount them either on the sides of the box or on the inside top so the connectors and cables have plenty of room to turn towards the bottom of the box and exit.

Mount the amp meters on the cover of the box with a master disconnect switch and you have a very nice setup that is weatherproof. All of the outlets are concealed inside.

Edit - I just did a quick search and there are several good candidates on Ebay under $200.

 

[LuckyDog]

Surprised no mentioned this: http://www.surpluscenter.com/Electr...s/120-240-VAC-GENERATOR-PANEL-BOX-11-3306.axd

I mounted one to my 002A and a 50 Amp welder plug. I have a second one that I may put a SOJ cord on, to plug into the panel and get away from the generator (i.e. run into a garage). Just an idea.


ETA: I rewired it internally. The two 20 Amp CBs feed the 120 outlets. The 30 Amp outlet is wired direct to the generator and relies on the generators master circuit breaker.

 

[lonesouth]

I saw those after a little more digging. Have 3 on order. Still planning to run the breaker box, with individual breakers for each outlet, and will replace the 30amp outlets in two of the boxes with a 20 and 50, so I've got most of the common plug ends covered.

 

[lonesouth]

BTW, I just discovered what these panels were used on.

B&S gensets

http://www.instructables.com/id/Eas...ermine-your-generator-plug-type-and-amperage/