Interlock for Generator

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  #1  
Old 08-07-20, 09:05 AM
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Interlock for Generator

Why are these damned thing SO expensive? A couple of pieces of sheet metal and some screws? They don't even give you the breaker or the receptacle? Some "kit."


And it's not the little UL Approved sticker because I asked my local inspector who said he would pass/fail a DIY setup based on it's performance and integrity.

My question: what kit do I need for my panel? I cannot for the life-of-me, determine which one I need?

My panel is:
Siemens G2020MB1100 -- Series .E -- Enclosure Type 1 -- B2598 100 amp

Looks like this:





TIA!!
 
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08-07-20, 02:01 PM
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I don't know why someone suggested 40A. The gen 120/240 outlet is protected by a 30A breaker so that's the max amps it can supply. Use a 30A double pole breaker in the main panel. I like the inlets that the cord hangs from the bottom, puts less stress on the socket.
Such as this.... https://www.homedepot.com/p/Reliance...E&gclsrc=aw.ds

Edit: Actually there isn't a 40A power inlet, you have to jump up to 50A. Then that is making things convoluted. You could put in a 50A breaker and inlet using #6Cu for a larger gen in the future and use a connection cable that is for a 30A Gen to 50A inlet connection.
 
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Old 08-07-20, 09:25 AM
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Oh yeah, the breaker for the generator will go just under the MAIN, top 2 slots on the right, and it will be a 30 or 40 amp, dual pole. I'll move those 2 red-switched breakers down, there's plenty of room there.

THANKS!!



 
  #3  
Old 08-07-20, 12:00 PM
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This appears to be what you need...
https://www.geninterlock.com/product...h-100a-panels/
 
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Old 08-07-20, 12:13 PM
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Hi, donít see any UL listing on that device.
Geo
 
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Old 08-07-20, 12:23 PM
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It has a UL sticker big as day on it.
 
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  #6  
Old 08-07-20, 12:53 PM
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Thank you sir!!

What size cable should I run from the panel to the receptacle?

And while I got you here, which receptacle do I need?

This is my generator specs and a pic:
Running Watts - 7500w
Starting Watts - 9500w
Rated Frequency - 60HZ
Rated Voltage - 120V/240V
Rated Current - 60A
Receptacles (qty.) - (4) 120V AC; (1) 240V/120 AC; (1) 120V 30A AC; (1) 12V 10A DC




Any advice, observations or suggestions are greatly appreciated.


THANKS!!
 
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Old 08-07-20, 01:14 PM
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The gen 120/240 outlet is 30A, so use 10/3 w/ground NM-b from panel to a 30A power inlet.
 
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  #8  
Old 08-07-20, 01:24 PM
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Got it!

And with a dual pole breaker, that'll "lite up" the entire service, both buses, right?

Someone said to use a 40A dual-pole, 10 amps higher - why would they suggest that?



30Amp Power Inlet

 
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Old 08-07-20, 02:01 PM
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I don't know why someone suggested 40A. The gen 120/240 outlet is protected by a 30A breaker so that's the max amps it can supply. Use a 30A double pole breaker in the main panel. I like the inlets that the cord hangs from the bottom, puts less stress on the socket.
Such as this.... https://www.homedepot.com/p/Reliance...E&gclsrc=aw.ds

Edit: Actually there isn't a 40A power inlet, you have to jump up to 50A. Then that is making things convoluted. You could put in a 50A breaker and inlet using #6Cu for a larger gen in the future and use a connection cable that is for a 30A Gen to 50A inlet connection.
 
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Old 08-07-20, 04:26 PM
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Thanks SO much pattenp - much appreciated!!

Yeah, you're right - 40amp breaker doesn't make any sense? I'm going with just what you suggested.

The only item left is the cable from the generator to the inlet. I'm assuming making one will save money over buying one, correct? Should I use that same 10/3 w/ground NM-b you suggested for the panel-to-inlet run?

Also, in your opinion, which should I make longer - the cable from the panel to the inlet? Or the cable from the generator to the inlet? Or is that a proverbial "6 of 1, half dozen of the other?"


 
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Old 08-07-20, 04:37 PM
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You need to use SJOOW cord and put twist lock plug and socket on it for connecting the Gen to the inlet. You may find it's just as cheap to buy a pre-made cord. The location where you need to place the inlet will determine wire length to go from panel to inlet. Never use NM-b as a cord.
 
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  #12  
Old 08-07-20, 04:48 PM
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OK, I see the UL listing ,wasnít looking at that page.
Geo🇺🇸
 
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Old 08-07-20, 07:49 PM
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Also, in your opinion, which should I make longer - the cable from the panel to the inlet? Or the cable from the generator to the inlet? Or is that a proverbial "6 of 1, half dozen of the other?"
You want the receptacle in a convenient location.
You want enough service cable to keep your generator away from the house.

Pre-made cords are more cost effective so keep that in mind when locating the receptacle.
 
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Old 08-07-20, 09:35 PM
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Thanks again pattenp - thanks PJmax

I'm making up my materials list- gonna be around $300! Dang, that's a lot! But with my luck, once I buy everything and get it installed, I'm pretty much guaranteed to never lose power gain.

Quick observation: I'm buying 10/3 romex (panel-to-inlet) - and the pre-made cord I need (inlet-to-gen) is labeled 10/4 - I'm pretty sure these are the right parts and they go together -- but why do they have those different nomenclatures? Is it just to confuse dummies like me?



50 ft. 10/3 Solid Romex SIMpull CU NM-B W/G Wire




40 ft. 10/4 SJTW 30 Amp 125-Volt/250-Volt 4-Prong L14-30 Transfer Switch Cord/Generator Extension Cord



 
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Old 08-07-20, 09:50 PM
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A cord's specs are the total amount of conductors. 10-4 is four insulated conductors.
NM-b cable is 10-3 w/ground. Still four wires but the ground is bare.
 
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  #16  
Old 08-08-20, 06:27 AM
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So PJmax , needless-to-say, 10/3 romex and a 10/4 extension cord IS, in fact, what I need, correct?

They DO in fact work properly together, right?





 
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Old 08-08-20, 07:09 AM
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The 10/3 NM and the 10/4 cord you've shown is correct. Do you understand the proper installation of NM?
 
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Old 08-08-20, 08:28 AM
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I believe I do, I consider myself quite capable -- I have worked successfully with non-metallict romex many, many times before but alas, I am NO expert, not even close. Really just an eager harry-homeowner who respects safety, doing things right, and the law.

But I'm surely willing, and appreciative, to hear you share your expertise with me about proper installation.

Please do.

Thanks!!

 
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Old 08-08-20, 11:58 AM
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My suggestion is to read NEC Article 334 to make sure you have an understanding of installation requirements.
 
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Old 08-10-20, 06:30 AM
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Did that, thanks.

I have a very good understanding and a strict adherence to regulated safety precautions and text-book installation procedures - that's never been my issue. I have a good-set-of-hands, quality tools and a level head.

But what I don't have - and the reason I so greatly value yours/everyone's advice here, is experience and the expertise of a professional - and the suggestions, the observations, the tricks-of-the-trade if you will, and subtle and the not-so-subtle nuances that come with experience.

Thanks again for sharing, it is very much appreciated.

 
  #21  
Old 08-10-20, 06:11 PM
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I'm in @ratdude's position - tired of the extension cords and with predictions of a worse than usual Atlantic hurricane season, I need to get this done.

Does the breaker power from the generator is fed through need to be GFCI since the outlet (technically inlet) is outside (i.e., a wet area)?
 
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Old 08-10-20, 06:20 PM
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No..... you don't want a GFI on the generator protecting the circuit. Some generators come with the 30A receptacle protected by a GFI breaker. I would not recommend that type of generator.
 
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  #23  
Old 08-11-20, 12:48 PM
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Purchased everything today - Amazon had the best prices. I spent, with tax, a few bucks over $200. Less than I originally anticipated. So far, so good.

- Siemens ECSBPK02 Generator Standby Power Mechanical Interlock - $27.00

- Champion 25-Foot 30-Amp 250-Volt Generator Power Cord for Manual Transfer Switch (L14-30P to L14-30R) - $49.99

- Reliance Controls Generators Up to 7,500 Running Watts PB30 30-Amp NEMA 3R Power Inlet Box, Gray - $49.98

- Q230 30-Amp Double Pole Type QP Circuit Breaker - $9.86

- Southwire 63948422 50' 10/3 with ground Romex brand SIMpull residential indoor electrical wire type NM-B, Orange - $54.62





 
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Old 08-16-20, 04:13 PM
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All supplies have been delivered! Very excited!

Question: This main panel has neutral and ground (white and bare) all attached to the same bus.

Is that okay to do when I wire in the new inlet as well?





(This isn't it but it kinda looks like this.)
 
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Old 08-16-20, 04:40 PM
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Yes, the inlet wire is connected the same way with the neutral bonded.
 
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  #26  
Old 08-16-20, 07:30 PM
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Can NM-B romex be run through a concrete wall to the exterior inlet without conduit? Or is an exterior outlet/inlet considered a wet area by the NEC and UF wire required?
 
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Old 08-17-20, 09:06 AM
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Thanks SO much pattenp - your assistance has been immeasurable.

Is there a min height required by code for the inlet box?

Without adding some conduit to raise it higher, mine would end up about 10" from the ground - outdoors, but in a very dry, pretty sheltered location with no chance of standing/running water ever coming in contact..

(This should be my last question at the risk of becoming a true PITA?)




 
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Old 08-18-20, 03:57 PM
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NM, I raised the inlet up to around 22 inches just because. Tomorrow, I'll do the very last step and that is to add the breaker and wire it to the panel. Even with the MAIN breaker off, those 2 110's will still be live where they are screwed in to the MAIN breaker.

So, should I pull the meter?

I forget, couldn't the braided bare coming from the meter be a threat if there was a short somewhere?








 

Last edited by Ratdude; 08-18-20 at 04:21 PM.
  #29  
Old 08-19-20, 07:23 AM
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***BUMP***

No love for the Ratdude.

I guess I asked too many questions.



 
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Old 08-19-20, 07:54 AM
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Wait for the pros to respond, but just in case you're tempted to act before hearing back, do not pull the meter. I think electricians use safety equipment when pulling and reconnecting the meter. Also, depending on your AHJ, it may not be legal for someone who isn't a licensed electrician or PoCo employee to pull the meter.

You're correct that the screw terminals on the main breaker will still be hot after the breaker is turned off. If your concern is accidentally touching those screws or the exposed ends of the cables entering the main breaker while installing the backfeed breaker and interlock, you could cover that with a few layers of electrical tape, but pros may have other suggestions.
 
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Old 08-19-20, 11:52 AM
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Thanks cartman -- I went ahead and did it without pulling the meter. It was easy - I just work myself up sometimes trying to make sure I'm safe. Pics below.

Hey, while I got you hear - is there a max degree bend you can make in 10/3 romex? I wanted to have some "future use" by perhaps moving the inlet box close to the natural gas/grill - so I made a couple of sweeping bends in the romex before going through the wall to the inlet box.

But now I think I remember that there is a reg on bending cable. You remember?






 
  #32  
Old 08-19-20, 12:06 PM
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"Sweeping bends" sound fine. Think about all those professionally installed panels with 90* bends in the hots as they turn into the breaker.

When you mounted the inlet, did you run any conduit through the wall, or just bare romex through hole just large enough for 10/3 romex? Secured to inlet box with which style of clamp? Some clamps that we use indoors would push the inlet box away from the wall (assuming you ran wire through knockout in the back of the box). I'm still waiting on my inlet box.
 
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Old 08-19-20, 01:48 PM
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Thumbs up

Originally, I planned to run the romex thru the wall, directly into the inlet box. And although I couldn't find any code on minimum height requirements, I felt the box was too low. So, I ran to Homer and picked up the LB (right angle) and a PVC fitting>clamp - I already had some 2", outdoor (gray) PVC so I didn't buy any but it's super cheap $2 bucks for 10 feet) - and raised the inlet box up to around 23 inches.




The clamp to the inlet box I used was one like this:


They're supposed to be screwed into a PVC box with threads so I had to use a locknut ring from a normal metal clamp, and that worked fine. You could do the same but your hole through the house would need to be big enough to accommodate that 1/2" fitting. And that fitting is probably the best way for you to go because it's round, not odd shaped and should fit nicely in a drilled out hole.

One more trick I can share - most clapboards are slanted, so I cut a small shim out of the 1/2 inch PVC conduit, and placed it in the back of the box, centered on the top mounting screw-hole and screwed right thru the middle to make the inlet box sit level and plumb.

 
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Old 08-21-20, 01:40 PM
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I want to run 10/3 wire from the interlock breaker in the main panel out to the inlet. What's the easiest code compliant way to do so?

This is the 30A non-metallic inlet I'm using.



I'd like to run the wire directly into the knockout on the back of the box (KO size is 3/4", but there's a reducer if I want to bring it down to 1/2"). The back of the box does have a slight standoff, so it won't be flush with the wall, providing a little bit of space for a clamp to secure wire as it enters KO.


Hole in basement wall will be in the circled area. Since this is an accessible area, I figure the wire must be in conduit. And if conduit is used, I suppose the wire should be THHN, not romex.


On the exterior wall, the box would go in the red square area. The hole will be ~30" above grade.


I don't have any experience with conduit (just romex behind walls) and the options are confusing. What is the easiest code compliant way to run wire to this inlet box? And preferably making the smallest hole possible in the wall. Thanks for any suggestions.
 
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Old 08-21-20, 06:16 PM
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I'd connect the inlet to a LB conduit body inside via a short piece of conduit through the wall. Then you can run the romex up or down the inside wall or whatever direction you need. You just need to clamp/secure the romex where it enters the conduit.
FYI: Romex can be placed in conduit. PVC conduit is the easiest to use.
 
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Old 08-21-20, 06:27 PM
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I'd connect the inlet to a LB conduit body inside via a short piece of conduit through the wall. Then you can run the romex up or down the inside wall or whatever direction you need. You just need to clamp/secure the romex where it enters the conduit.
If I'm understanding you correctly, LB on the interior wall, connected to rear KO of inlet via short piece of conduit. Preference for LB and conduit material - pvc vs one of the metallic conduit types?

I can't run bare romex from main panel to the LB, can I? Seems like the location is one that is exposes the wire to physical damage, which is why I was thinking a conduit might be required (and thus THHN to keep conduit size down).
 
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Old 08-22-20, 04:44 AM
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The subject to damage in code is somewhat subjective. Not seeing your actual conditions it's hard to say if bare romex is okay to use from the panel to the wall exit. You can use PVC or EMT conduit sleeves where needed to protect the romex. Otherwise use a complete conduit run and pull thhn. PVC is okay, but if you want EMT go for it.
 
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Old 08-22-20, 05:42 AM
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Slight change of plan. It occurred to me that having the inlet box so low to the ground would create a slight hassle when plugging in the generator cord because it's too low to take a look at the downward facing inlet male plug's orientation. If this were a connection I was making regularly, I'm sure I'd get used to the orientation without looking, but since it will only be used during power outages, I could see this being a minor hassle each outage. So I'm thinking drill the hole in same approximate location, but mount the inlet box 1-2ft higher (where the brick is), so that means I'd have conduit running up from the hole to the inlet's side KO.
https://i.imgur.com/qe2DFMY.jpg

As for conduit, I was doing a little reading on the various kinds last night. What about liquidtight flexible non-metallic conduit, such as this: https://www.homedepot.com/p/Southwir...4221/100175539

With PVC or EMT, I'd have to use several fittings to make the run, but with this flexible NM conduit, it seems I could run it with just two fittings - one at the panel and one at the inlet box. Never used this (or any) conduit before, so I'm not sure if there's anything I'm missing that would make it a poor choice for this application.

I guess the THHN sold by the foot at Home Depot is also THWN since it says it can be used in wet or dry locations: https://www.homedepot.com/p/Southwir...4099/204631946
Seems this would be a good choice. Looks like it's available in stranded or solid. Does it matter for this application?

Checking a conduit fill table, looks like 4 #10 wires in 1/2" conduit is not a problem.
 
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Old 08-22-20, 07:15 AM
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And now I'm seeing why you suggested the LB. Even with liquidtight flexible non-metallic conduit, I'd probably need a LB on either side of the hole since it looks like flex conduit can't make a sharp 90* turn, so the LBs are needed to keep the conduit against the wall for aesthetic purposes.

Can I use liquidtight non-metallic conduit with PVC LB fittings? Would those joints need the same PVC glue that's required for PVC conduit and PVC fitting joints?
 
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Old 08-22-20, 07:40 AM
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There are fittings for connecting liquidtight to conduit bodies.
 
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