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DIY interlock for generator

20K views 60 replies 19 participants last post by  tylernt 
#1 ·
#5 ·
No good

It's a great diy scheme however I am sure somewhere, somehow, some date long ago someone already did this and probably isn't among the living anymore. Naturally or by accident.
As long as man has been alive people have tried to save a buck and lost their lives.
Don't mess with electric install an approved interlock or have one installed by a real electrician.
The codes are written for a reason so people don't die.
 
#4 ·
Anyone got some ideas? Thanks!
Yes. You can't do it. The kit has to be UL listed. If you make your own, it is not listed and is a code violation.
 
#6 ·
If it was just his life, maybe the objection wouldn't object be as great.

But, if his jury rig device fails to work properly and he back feeds the grid, he could kill one or more linemen. (Usually, the 120V becomes 12,000V when you back feed the first transformer)

Trying to save a few bucks for the approved and tested device is not worth the risk you are putting onto others.
 
#7 ·
The scary thing about that instalation is tha someone randomly drilled and put screws into that dead front. Part of the UL listing that approved devices get include the install instructions for the particular panel it is to be installed on. A homeowner engineered device like that could come in contact with the bus bars inside the box with less than favorable results.
 
#9 ·
What is unbelieveable is that you appear to have ignored numerous people that have told you that making your own interlock is in no way correct code-wise or liability-wise. I guess you are just one of those that keeps going until they get the answer they want. :furious:
 
#11 ·
I have a new Siemens panel, 150amp, series A, type 3R.



I wouldn't mind buying a lockout kit but can't find the one for my panel, though maybe it's just bacause I don't see one that suits my budget and eye.
 
#15 ·
I wouldn't mind buying a lockout kit but can't find the one for my panel, though maybe it's just bacause I don't see one that suits my budget and eye.
For a Siemens panel that new just look on the cover sticker. It will list the part number of the factory interlock.
You do not always have to spend $150 at interlockkit.com for one of these things.

Sorry if you think you cannot find "one that suits your budget or eye", but that is just how it goes. DO NOT diy hack something together.
I already get the impression that you are the type to do whatever you want regardless of the consequences so I'll just leave it at that.
 
#12 ·
Could you please advise me where in the NEC that says the interlock has to be "listed" ? There is a lot of discussion going on in the "Electrician Talk" forum and everyone has a difference of opinion. If you know where it is "SO" stated, could you please share that article section? Thanks
 
#18 · (Edited)
Could you please advise me where in the NEC that says the interlock has to be "listed" ? There is a lot of discussion going on in the "Electrician Talk" forum and everyone has a difference of opinion. If you know where it is "SO" stated, could you please share that article section? Thanks
The kits made by interlockkit aren't UL listed, and that may be what they're discussing at Electrican Talk.

Here's what their site says:

Tested for use with UL 67 Listed Panelboards
Ref. Wyle Laboratories Test Report T52431-01
Wyle is a Nationally Recognized Testing Laboratory authorized by OSHA for UL standard 67 and recognized by all 50 US States.
http://www.interlockkit.com/warranty01.htm

Wyle is no longer a Nationally Recognized Testing Laboratory. I believe it was when they did the testing on interlockkit's products.

***

That has nothing to do with interlock kits made by other companies.

This also doesn't necessarily mean that the interlocks made by Interlock Kit don't work. I have read somewhere that some inspectors won't pass them because they are not UL listed, however, and that they have had trouble getting them permitted for jobs in one state (I believe it is Washington). If someone with real experience can shed light one this, that might help some other readers.
 
#13 ·
I'm over at that site quite a bit, and I don't remember a discussion about generator interlocks not being listed.

90.7 Examination of Equipment for Safety. For specific
items of equipment and materials referred to in this Code,
examinations for safety made under standard conditions
provide a basis for approval where the record is made generally
available through promulgation by organizations
properly equipped and qualified for experimental testing,
inspections of the run of goods at factories, and servicevalue
determination through field inspections. This avoids
the necessity for repetition of examinations by different
examiners, frequently with inadequate facilities for such
work, and the confusion that would result from conflicting
reports on the suitability of devices and materials examined
for a given purpose.
It is the intent of this Code that factory-installed internal
wiring or the construction of equipment need not be
inspected at the time of installation of the equipment, except
to detect alterations or damage, if the equipment has
been listed by a qualified electrical testing laboratory that is
recognized as having the facilities described in the preceding
paragraph and that requires suitability for installation in
accordance with this Code
 
#16 ·
Model number W4040L. Hey, and while I was looking at the cover sticker I found the interlocks it accepts! ECSBPK01,02,03,05,06 or 07. Prices range from $20 to $60. I guess I'll go for the cheapest one, why not?

Thanks for all the help - those of you who did!

puttster
 
#17 ·
Model number W4040L. Hey, and while I was looking at the cover sticker I found the interlocks it accepts! ECSBPK01,02,03,05,06 or 07. Prices range from $20 to $60. I guess I'll go for the cheapest one, why not?
That is exactly what I was talking about, the part number of the interlock. Most companies do make factory interlock kits for a fraction of the cost of aftermarket.
 
#20 ·
What COLDIRON said in his first post: don't get too confident when you're messing around with your main entrance. Lot of amps in there will mess you up real bad - real fast. Be careful! Paying an electrician $100 to install this is so much cheaper than getting injured. Had a friend wiring in a new circuit to his main panel, touched a conductor in the box accidentally, it shocked him and sparked a little. He reacted instinctively by pulling back very quickly and when he did, knocked his head on the nearby stair riser so hard he fell over almost knocking himself out and breaking his finger when he fell! Again, just be careful. That DIY interlock thing on youtube looks like a complete hazard.
 
#22 ·
It's the same panel as mine just with a 150 amp breaker and not a 200 I am going to be installing the interlock kit on mine this spring. I refuse to tie my generator into my main panel without all listed devices being installed and installed properly. For now I just use an extension cord for the fridge and some other small stuff and in the winter some small heaters.
 
#23 ·
#24 ·
Looks kind of dangerous but with a UP approved interlock, what to worry?
An inlet is only dangerous without an interlock or transfer switch. The interlock/t-switch ensures that utility power will never energize the male prongs.
 
#25 ·
How can you afford a generator if you are too poor to buy an interlock kit?

I wouldn't even consider an interlock kit. Either run extension cords directly from your generator to the appliances you need to power, or install a proper transfer switch.

I'm cheap, and I just went through this myself, trying to decide on how to hook up my generator, and after doing the research, I concluded that a transfer switch is the best and most economical way to go. Now I'm just trying to figure out exactly what kit to order, but the whole thing will probably set me back about $300.

A basic transfer switch isn't that much more expensive than an interlock kit. Your still gonna have to spend money on wiring and inlets and whatnot, so I would do it properly while you're at it.

You might be able to fabricate your own interlock, but how are you planning on getting that through inspection? Having the inspector come back twice is probably gonna set you back more than the $100 - $200 you saved on not just getting a transfer switch from the get go.
 
#26 ·
A basic transfer switch isn't that much more expensive than an interlock kit. Your still gonna have to spend money on wiring and inlets and whatnot, so I would do it properly while you're at it.
An OEM interlock, from the panel manufacturer can be substantially cheaper than a transfer switch and is much easier to install - and UL Listed and approved.

In addition, under generator power your transfer switch bypasses AFCI and GFCI breakers - a possible issue with your inspector and it also limits the number of circuits you can run. My Murray interlock affords AFCI protection and allows me to choose any circuit to be powered.
 
#27 ·
In addition, under generator power your transfer switch bypasses AFCI and GFCI breakers - a possible issue with your inspector and it also limits the number of circuits you can run. My Murray interlock affords AFCI protection and allows me to choose any circuit to be powered.
HUH?:huh:
 
#29 ·
When I made the post I was thinking he means the typical 6 or 10 circuit type transfer switch panel. The last post confirms it.

When on generator mode, you bypass any AFCI or GFCI breaker protection. Power is being fed from the generator, through the transfer switch circuit breaker, and then into the switched circuit. There is only one neutral from the transfer switch, not one for each circuit.
 
#32 ·
My Idea for a 120 Volt Genny tied into a sub



This is my Idea that I had the other day. I am not sure it if meets code or not. I have a couple of spare 50 amp breakers so I don't have to pay for that, and all of the other breakers would move out of my existing box. I did inquire with the local electrical inspector, and he say you may make a 120 Volt only panel by tying busses together but the panel had to be labeled "120 Volts ONLY" and the tie has to be the right gauge wire to handle potential load. He suggested bringing in the entrance from the main panel on a breaker and then tying the bus together on the main lugs for the sub panel.

i haven't ran the back feeding part for a generator by him yet though.

The Ideal here is that the Double pole breaker for the Gen. can only be engaged when the main breaker is disconnected. One pole brings the Gen power in and the other pole energizes the other bus. This allows me to still draw my circuits off of both sides of the transformer for a balanced load when under normal power but when the generator is engaged the whole panel goes 120 Volts from the Gen.

I have read that is is legal to run 120 off of a single pole in a double pole breaker, but i haven't found the actual NEC code for it.

The panel is $39, The Interlock is $25 (From Square D) The breakers I already have from when I they replaced my electric service 6 years ago (Insurance Company paid for it, because of storm damage and they wanted all new from the entrance to the panel and all breakers) They left me all the old stuff so I have it all.

This diagram is only showing the hot wires at this point, not the neural or ground. i will isolate the ground and neutral buss and run two separate wires from the main. The Gen will also be grounded to the same ground rod as the main panel outside.

Would appreciate feedback or comments.
 
#38 ·
One last question. I'll have a 10 ga cable from the generator to the receptacle on the beaker panel box. What is the minimum gauge needed from the receptacle to the breakers (about 18")? Generator is a 4000 watt peak and breakers will be dual of 15 amps each.
 
#39 ·
One last question. I'll have a 10 ga cable from the generator to the receptacle on the beaker panel box.
By receptacle, you mean an inlet with male prongs, right?

What is the minimum gauge needed from the receptacle to the breakers (about 18")? Generator is a 4000 watt peak and breakers will be dual of 15 amps each.
What size is your backfeed breaker? If 30A, use 10ga. If 20A, use 12ga. If 15A, use 14ga. The size of the generator breakers is unimportant, go by backfeed breaker size.
 
#43 ·
Here is my set up. Pictures

Siemens Load Center P4260B1225CU is my Load Center here. I upgraded (rather lateral'ed) my Main Load Center from SIEMENS G4040MB1200.

Bought the whole new Load Center Assembly and just swapped the "GUT" out. In the process, I ended up going from 200A to 225A. Surprisingly I found the P4260B1225CU Load Center from Amazon.com for $169 including shipping.

I had to DREMEL cut the piece of metal (on the Dead Cover) between the Main Breaker and the Generator Breaker, otherwise the interlock "feature" of the KIT would not work. How many of you all had to do what I did, I am wondering.... See pics below.

Note the small sticker on the kit that said, "UL LISTED". I guess this is why Siemens can demand and fetch $50 for a lousy small piece of metal.... Tse.. tse..




 
#46 ·
I had to DREMEL cut the piece of metal (on the Dead Cover) between the Main Breaker and the Generator Breaker, otherwise the interlock "feature" of the KIT would not work. How many of you all had to do what I did, I am wondering....
While mine is a different version of that interlock, I didn't have to cut any sheet metal. Just hold the main breaker interlock out of the way when you put the cover on. Both interlocks clear the panel cover easily.
 
#58 ·
Been a while, I am the OP. I have my list of materials and was just waiting for hurricane season to purchase them. Waiting and thinking.

Near my back door are two recepticles, each on different power bars, #12 and #18 breakers. If I wheeled the 4000 watt generator up close to them, used two 14 ga 120v suicide wires to power those circuits, could I accomplish the same thing as my interlock plan, electrically? Obviously it would be somewhat less safe because I would have to remember to plug in the wires and open the main power breaker before starting the generator.

Are there any other differences in these two approaches?

puttster
 
#59 ·
#12 and #18 breakers.
What's a #18 breaker? Breakers come in 15A, 20A. Wire comes in 14ga, 12ga. 18ga is too tiny for electrical wiring.

If I ... used two 14 ga 120v suicide wires to power those circuits, could I accomplish the same thing as my interlock plan... I would have to remember to plug in the wires and open the main power breaker before starting the generator.
An interlock forces you to turn off the main before backfeeding your generator. If you have to "remember" to do it, that's the exact opposite of an interlock.

Suicide cords and "remembering" are illegal and dangerous. The only way you can be safe and legal is to use a UL-listed interlock (or transfer switch) and a generator inlet. Not sure what else there is to discuss at this point, unless you need help selecting and installing your UL-listed interlock and generator inlet.
 
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