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Discussion Starter · #1 · (Edited)
I need to add a 50a inlet with a transfer switch so I can feed various circuits during power outages.
In reviewing the setup it appears an easy path to outside for adding the 50v inlet would be to feed 6g wire back from the breaker and interlock through the wall where the power is coming in from my outdoor main cutoff and then branch off of that box down or to the right.

Is this ok to do? Meaning to operate off of the main cutoff box. Otherwise I’d just have to bore another hole through the stucco which is doable but certainly not preferable unless needed.

I can turn off the whole house power via the main breaker outdoors but the power feed into that breaker will still be hot from the meter. As you can see from the pictures the power in will be in the way but I could work around it. I know to steer clear of the lugs but is that a bad idea to even be working around the hot cable even though it is coated?
I appreciate any and all advice.


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Yes, that looks fine to me. The wire coming through the wall is feeder since it is after the main breaker. You are allowed to have feeder and other feeder in the same conduit.

310.15(B)(3)(a) thermal derate won't apply since the two feeders are mutually exclusive and cannot be used at the same time.

You can use #8Cu THHN for 50A. Normally I'd be shouting from the treetops to use aluminum for cost savings, but you're going 4 feet for Pete's sake.

Use EMT conduit and metal boxes and ground will be taken care of, provided the passthru through the wall is also metal conduit.
 

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Do you have a main on the indoor panel? You must have an interlock in conjunction with the main. That is to say you cannot be physically able to turn on both utility main and generator input at the same time.
I suggest that you contact a pro in your area. You can not connect 50 volts to a 120/240v system with out a lot of problems.
I suggest that you contact a pro in your area. You can not connect 50 volts to a 120/240v system with out a lot of problems.
clearly they meant 50 amps
 

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Discussion Starter · #7 ·
Thanks for the input so far.
to the question about the interlock- it will be on the first inside panel which is in the garage opposite that outdoor main box. It too has a main breaker which would cut the power from the utility to the house.

I planned to run the wire from the inside panel new 50a breaker through that conduit (where the feed is coming in) and out the side or bottom of the outdoor box. I would have looked to put the interlock on that outdoor main panel but it isn’t built for another breaker.

Here is the pic of the panel inside the garage.

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Discussion Starter · #9 ·
Yes there is. It’s a Cutler Hammer panel.

My question is whether it’s ok to be manipulating that live 120v input from the meter which comes straight across and then up to the top lug. I’ll no doubt touch the insulated wire when installing the conduit and then pulling the wire.That’s really the only part that has me wondering. I believeI’ve done enough research on the rest.
 

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In the OP there was a mention of a transfer switch. A transfer switch could be installed and operated without touching the main breaker. The OP also said he was wanting to feed various circuits during power outages. That is exactly what the transfer switch is designed to do. I encourage the OP the purchase a transfer switch with the desired number of circuits and follow the installation instructions.
 

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Discussion Starter · #14 ·
Please do not kill a lineman. I'm sure you can make it work, but doubt you have any chance at all of doing it such that your friendly lineman is protected.
I appreciate your confidence in me. It’s very helpful on a forum like this. I’m not an idiot and an interlock can be done right and safely.
 

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In the OP there was a mention of a transfer switch. A transfer switch could be installed and operated without touching the main breaker.
There are (at least) 2 kinds of transfer switches. You're thinking of the 6/8/10 circuit "Reliance style" transfer switches.

OP meant a different type of transfer switch, which is one gigantic DPDT knife switch rated for 200A.

The OP also said he was wanting to feed various circuits during power outages. That is exactly what the transfer switch is designed to do. I encourage the OP the purchase a transfer switch with the desired number of circuits and follow the installation instructions.
I encourage OP not to to get a 6/8/10 circuit "Reliance style" one. Those belong in the 1970s. They are incompatible with many things (MWBC, AFCI, GFCI) and a novice installer will miss the subtleties, and create a hazard situation. It doesn't help that they're a spaghetti mess to install. These are a choice of last resort for panels that can't take another kind.
 

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There are (at least) 2 kinds of transfer switches. You're thinking of the 6/8/10 circuit "Reliance style" transfer switches.

OP meant a different type of transfer switch, which is one gigantic DPDT knife switch rated for 200A.

I encourage OP not to to get a 6/8/10 circuit "Reliance style" one. Those belong in the 1970s. They are incompatible with many things (MWBC, AFCI, GFCI) and a novice installer will miss the subtleties, and create a hazard situation. It doesn't help that they're a spaghetti mess to install. These are a choice of last resort for panels that can't take another kind.
The OP was talking about a transfer switch because that is what he said. The OP was also talking about stalling a 50 amp. breaker, the very breaker needed to install a transfer switch.
I just believed what the OP post. Where did you get what the OP MEANT??


 

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What distance from the main panel to the aux power source?
Given 50A, assuming 240v & a 75C system & 4% or less voltage drop over the length:
With copper it’s #8 & you can go to 150’ length & the copper weighs 30 lbs.
With aluminum it’s #6 & you can go to 150’ length & the alum weighs 11 lbs.

Scrap price/lb, $3 for copper & $0.60 for aluminum. Sounds like aluminum for you! :D
 

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The OP was talking about a transfer switch because that is what he said.
OP also said interlock, so that doesn't mean anything. But cut yourself some slack: it's normal to have a bit of word salad when talking to novices, and sometimes you have to approach it with a neutral perspective and look for clues.


Where did you get what the OP MEANT??
easy path to outside for adding the 50v inlet would be to feed 6g wire back from the breaker and interlock through the wall
That was fairly clear to me. Message 7 settles it: they mean a sliding-plate style of interlock on the existing 40-space CH panel inside. And that is consistent with the interest in making use of the conduit currently being used by the utility feeder to receive power from an outside inlet.

It's a simple, cheap and compact setup presuming a sliding plate interlock is available.

That is a very nice thing. They started with a "main panel", added a sliding plate interlock and possibly a motor drive to allow automatic throw... gave you as many as 12 additional breaker spaces, and then went to "thru lugs" to feed ALL the breakers in your regular panel. It's a good choice for sticking between a meter-main and a full panel, and I can see where you would think that a good fit for OP. I would say, versus a sliding plate interlock,

  • possible ATS
  • more breaker spaces, a very big deal IMO
  • large box to mount somewhere
  • more complex 200A cable routing, and that can't share a conduit, so 2 conduits to plumb
  • cost
 

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Discussion Starter · #19 ·
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I should have posted a completion post a while back. Reading back over this I should have posted this being more thoughtful as I was just typing it out on my phone and not proofing which led to some typos and “word salad” as was noted. Rambling quickly can do that and was not my intention. I do appreciate those who were attempting to be helpful. This is labeled as a DIY chat room which would indicate it is a place for thoughtful and capable DIYers to trade ideas and check plans with others.

I ended up using an interlock and have a backup safety in that the main supply can also be switched by it’s master breaker. Either way with the interlock it is not possible to backfeed to the supply lines. I had to move the breaker which feeds a sub panel to make room which was no problem. I plan to turn all breakers off and then after switching over the the generator I will engage a few breakers for our refrigerators and then some various outlets along with the furnace blowers and just rotate the breakers as needed. No plans to power everything as this was just an emergency backup project.

I didn’t post anything about the natural gas line but of course I had to add a tee and gas cutoff with quick connect for this as well. All in all very happy to have done this.

As you can see from the first picture this panel labeling is sloppy and a mess. It appears the original installer when they built the house was not only sloppy but wasn’t good with English spelling. Relabeling will be a project for another day…
 
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