Pop conduit thru stucco and up into main panel?

[jerryk1234]

Hello!

My electrical utility has decided to take our power away - occasionally - to prevent fires. So I have ordered a modest backup generator. To conveniently power the house without running extension cords everywhere, I need a transfer switch.

I have tentatively identified the switch I'd like to use - a Reliance exterior-rated unit, 30A, 10 circuits. It's quite wide, and will intrude into the space occupied by a telephone/cable box. But it will work if I mount it to the side of the house on 2" spacers.

The main panel is flush-mounted in the exterior stucco wall.
There is a junction box under the main panel that is surface mounted, and communicates with the main panel via a 1.5" conduit with some big wires ( which power our swimming pool, spa & sauna ). The junction box is almost empty.

I propose to mount the transfer switch next to the junction box - with a minimal length piece of conduit. Wires from the switch will go through the junction box and hence into the main panel. There will be 22 12-AWG THHN wires. Two wires for each circuit, plus a neutral, plus a ground. I believe the neutral is needed because there is a pair of wattmeters in the switch.

My question is - how do I get from the junction box into the panel? The existing conduit looks pretty full. So is the bottom of the panel. There are a couple of unused 1/2 inch punchouts, and space in a few romex clamps. There also might be a bit of legal space left in the existing 1.5" conduit - but not enough for 22 #12's!

I suppose I could run a pair of 1/2 flex conduits from the panel bottom , through the stucco, into the junction box. Doesn't look like much fun - the underside of that panel has to be just as crowded as the inside.

There is another concept that would have worked if we didn't have solar - an "interlock" - basically, an elegantly shaped piece of sheet metal mounted to the front of the panel. It slides back & forth, and guarantees that the "generator" breaker is never on at the same time as the main breaker. Can't use it because we have solar. No way to guarantee that the solar breaker isn't on at the same time as the generator breaker.

Anyway - anybody have hints or comments about how to get from the panel into the junction box?

Thanks in advance,

- jerryk1234

 

[Pete999]

Hello!

My electrical utility has decided to take our power away - occasionally - to prevent fires. So I have ordered a modest backup generator. To conveniently power the house without running extension cords everywhere, I need a transfer switch.

I have tentatively identified the switch I'd like to use - a Reliance exterior-rated unit, 30A, 10 circuits. It's quite wide, and will intrude into the space occupied by a telephone/cable box. But it will work if I mount it to the side of the house on 2" spacers.

The main panel is flush-mounted in the exterior stucco wall.
There is a junction box under the main panel that is surface mounted, and communicates with the main panel via a 1.5" conduit with some big wires ( which power our swimming pool, spa & sauna ). The junction box is almost empty.

I propose to mount the transfer switch next to the junction box - with a minimal length piece of conduit. Wires from the switch will go through the junction box and hence into the main panel. There will be 22 12-AWG THHN wires. Two wires for each circuit, plus a neutral, plus a ground. I believe the neutral is needed because there is a pair of wattmeters in the switch.

My question is - how do I get from the junction box into the panel? The existing conduit looks pretty full. So is the bottom of the panel. There are a couple of unused 1/2 inch punchouts, and space in a few romex clamps. There also might be a bit of legal space left in the existing 1.5" conduit - but not enough for 22 #12's!

I suppose I could run a pair of 1/2 flex conduits from the panel bottom , through the stucco, into the junction box. Doesn't look like much fun - the underside of that panel has to be just as crowded as the inside.

There is another concept that would have worked if we didn't have solar - an "interlock" - basically, an elegantly shaped piece of sheet metal mounted to the front of the panel. It slides back & forth, and guarantees that the "generator" breaker is never on at the same time as the main breaker. Can't use it because we have solar. No way to guarantee that the solar breaker isn't on at the same time as the generator breaker.

Anyway - anybody have hints or comments about how to get from the panel into the junction box?

Thanks in advance,

- jerryk1234

Isn't the Utility Company providing you with an adequate back up supply whilst they fiddle with the permanent supply? sounds a bit Heath Robinson to me, but I'm not in tune with the US rules and regs.

 

[jerryk1234]

Isn't the Utility Company providing you with an adequate back up supply whilst they fiddle with the permanent supply? sounds a bit Heath Robinson to me, but I'm not in tune with the US rules and regs.

They are not providing any backup supply, adequate or not. Just turning off the juice. Maybe for as long as 2 or 3 days. The idea is that we have had some tremendous fires in California over the past few years. Some of them were blamed on the utility's equipment. The utility had to declare bankruptcy as a result. So they are watching the weather. When the following combination occurs, they turn off the grid to hundreds of thousands of people:

• High and/or gusty forecast winds.
• No rain.
• Dry vegetation

So far, my own house has escaped turnoff. But the flow of energy no longer seems guaranteed.

We have PV solar. But it is grid-tied. So when the grid goes down, the solar goes down also. This is as it should be, because you don't want to feed power to the grid while people are out there trying to fix it.

 

[Megawatt]

Hello!

My electrical utility has decided to take our power away - occasionally - to prevent fires. So I have ordered a modest backup generator. To conveniently power the house without running extension cords everywhere, I need a transfer switch.

I have tentatively identified the switch I'd like to use - a Reliance exterior-rated unit, 30A, 10 circuits. It's quite wide, and will intrude into the space occupied by a telephone/cable box. But it will work if I mount it to the side of the house on 2" spacers.

The main panel is flush-mounted in the exterior stucco wall.
There is a junction box under the main panel that is surface mounted, and communicates with the main panel via a 1.5" conduit with some big wires ( which power our swimming pool, spa & sauna ). The junction box is almost empty.

I propose to mount the transfer switch next to the junction box - with a minimal length piece of conduit. Wires from the switch will go through the junction box and hence into the main panel. There will be 22 12-AWG THHN wires. Two wires for each circuit, plus a neutral, plus a ground. I believe the neutral is needed because there is a pair of wattmeters in the switch.

My question is - how do I get from the junction box into the panel? The existing conduit looks pretty full. So is the bottom of the panel. There are a couple of unused 1/2 inch punchouts, and space in a few romex clamps. There also might be a bit of legal space left in the existing 1.5" conduit - but not enough for 22 #12's!

I suppose I could run a pair of 1/2 flex conduits from the panel bottom , through the stucco, into the junction box. Doesn't look like much fun - the underside of that panel has to be just as crowded as the inside.

There is another concept that would have worked if we didn't have solar - an "interlock" - basically, an elegantly shaped piece of sheet metal mounted to the front of the panel. It slides back & forth, and guarantees that the "generator" breaker is never on at the same time as the main breaker. Can't use it because we have solar. No way to guarantee that the solar breaker isn't on at the same time as the generator breaker.

Anyway - anybody have hints or comments about how to get from the panel into the junction box?

Thanks in advance,

- jerryk1234

Jerry I just checked and you can pull 70 # 12 THHN singles in an 11/2 PVC Conduit according to the NEC in the annex section in the back of the book
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Hello!

My electrical utility has decided to take our power away - occasionally - to prevent fires. So I have ordered a modest backup generator. To conveniently power the house without running extension cords everywhere, I need a transfer switch.

I have tentatively identified the switch I'd like to use - a Reliance exterior-rated unit, 30A, 10 circuits. It's quite wide, and will intrude into the space occupied by a telephone/cable box. But it will work if I mount it to the side of the house on 2" spacers.

The main panel is flush-mounted in the exterior stucco wall.
There is a junction box under the main panel that is surface mounted, and communicates with the main panel via a 1.5" conduit with some big wires ( which power our swimming pool, spa & sauna ). The junction box is almost empty.

I propose to mount the transfer switch next to the junction box - with a minimal length piece of conduit. Wires from the switch will go through the junction box and hence into the main panel. There will be 22 12-AWG THHN wires. Two wires for each circuit, plus a neutral, plus a ground. I believe the neutral is needed because there is a pair of wattmeters in the switch.

My question is - how do I get from the junction box into the panel? The existing conduit looks pretty full. So is the bottom of the panel. There are a couple of unused 1/2 inch punchouts, and space in a few romex clamps. There also might be a bit of legal space left in the existing 1.5" conduit - but not enough for 22 #12's!

I suppose I could run a pair of 1/2 flex conduits from the panel bottom , through the stucco, into the junction box. Doesn't look like much fun - the underside of that panel has to be just as crowded as the inside.

There is another concept that would have worked if we didn't have solar - an "interlock" - basically, an elegantly shaped piece of sheet metal mounted to the front of the panel. It slides back & forth, and guarantees that the "generator" breaker is never on at the same time as the main breaker. Can't use it because we have solar. No way to guarantee that the solar breaker isn't on at the same time as the generator breaker.

Anyway - anybody have hints or comments about how to get from the panel into the junction box?

Thanks in advance,

- jerryk1234

Jerry just turn the breaker off feeding the wires in the junction box and cut the green wire and tie the wires to the green wire and as you pull out the green you pull in the new wires in the panel and don’t forget to repull the green wire you cut and with all the circuits you need to pull more than one neutral. I would pull a neutral for every circuit or at least 2 circuits per neutral
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Jerry I just checked and you can pull 70 # 12 THHN singles in an 11/2 PVC Conduit according to the NEC in the annex section in the back of the book
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Jerry just turn the breaker off feeding the wires in the junction box and cut the green wire and tie the wires to the green wire and as you pull out the green you pull in the new wires in the panel and don’t forget to repull the green wire you cut and with all the circuits you need to pull more than one neutral. I would pull a neutral for every circuit or at least 2 circuits per neutral

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They are not providing any backup supply, adequate or not. Just turning off the juice. Maybe for as long as 2 or 3 days. The idea is that we have had some tremendous fires in California over the past few years. Some of them were blamed on the utility's equipment. The utility had to declare bankruptcy as a result. So they are watching the weather. When the following combination occurs, they turn off the grid to hundreds of thousands of people:

• High and/or gusty forecast winds.
• No rain.
• Dry vegetation

So far, my own house has escaped turnoff. But the flow of energy no longer seems guaranteed.

We have PV solar. But it is grid-tied. So when the grid goes down, the solar goes down also. This is as it should be, because you don't want to feed power to the grid while people are out there trying to fix it.

They are not providing any backup supply, adequate or not. Just turning off the juice. Maybe for as long as 2 or 3 days. The idea is that we have had some tremendous fires in California over the past few years. Some of them were blamed on the utility's equipment. The utility had to declare bankruptcy as a result. So they are watching the weather. When the following combination occurs, they turn off the grid to hundreds of thousands of people:

• High and/or gusty forecast winds.
• No rain.
• Dry vegetation

So far, my own house has escaped turnoff. But the flow of energy no longer seems guaranteed.

We have PV solar. But it is grid-tied. So when the grid goes down, the solar goes down also. This is as it should be, because you don't want to feed power to the grid while people are out there trying to fix it.

Jerry that junction box is your path to the panel

 

[jerryk1234]

OK, I'm going to go count the existing wires in that conduit ( from the junction box to the panel ), and measure their diameters with a caliper. Then I should be able to use an online NEC calculator to figure out how many #12's I can fit in.

Neutrals: in general, I'm a fan of separate neutrals. I hate it when the lights brighten when the fridge comes on. Not sure if it's needed here though. The way the transfer works, is you have one switch for each individual circuit. So, at the main panel, current comes out of an individual breaker, goes out to the switch box, goes through the individual switch, and comes right back to the main panel, where it is connected to the original load wire. So any neutral in the transfer switch box is not used at all during normal operation.

Running off the generator is a different story. The neutral in the switch is the return to the generator. Also, it serves as the common lead for the twin wattmeters. But the run is very short. I'm pretty sure one beefy neutral will work fine for all of it. Remember - regardless of how many circuits I stack up, the whole thing is rated at 30A - total. There are a couple of existing neutrals in the junction box; maybe I could just tap off one of them with one of those split bolts?

This is the unit I'm considering:

https://www.electricgeneratorsdirect.com/Reliance-Controls-R310A/p61743.html

The disadvantage of this guy is that it's very wide. The advantage? It uses industry standard breakers, so I can put in AFCI's for the bedrooms.

I don't think I'll need to cut & pull any existing wires. The junction box is about 2 inches below the bottom of the main panel. Pretty sure I can just poke individual #12's through from below.

 

[Megawatt]

OK, I'm going to go count the existing wires in that conduit ( from the junction box to the panel ), and measure their diameters with a caliper. Then I should be able to use an online NEC calculator to figure out how many #12's I can fit in.

Neutrals: in general, I'm a fan of separate neutrals. I hate it when the lights brighten when the fridge comes on. Not sure if it's needed here though. The way the transfer works, is you have one switch for each individual circuit. So, at the main panel, current comes out of an individual breaker, goes out to the switch box, goes through the individual switch, and comes right back to the main panel, where it is connected to the original load wire. So any neutral in the transfer switch box is not used at all during normal operation.

Running off the generator is a different story. The neutral in the switch is the return to the generator. Also, it serves as the common lead for the twin wattmeters. But the run is very short. I'm pretty sure one beefy neutral will work fine for all of it. Remember - regardless of how many circuits I stack up, the whole thing is rated at 30A - total. There are a couple of existing neutrals in the junction box; maybe I could just tap off one of them with one of those split bolts?

This is the unit I'm considering:

https://www.electricgeneratorsdirect.com/Reliance-Controls-R310A/p61743.html

The disadvantage of this guy is that it's very wide. The advantage? It uses industry standard breakers, so I can put in AFCI's for the bedrooms.

I don't think I'll need to cut & pull any existing wires. The junction box is about 2 inches below the bottom of the main panel. Pretty sure I can just poke individual #12's through from below.

.
Jerry I wish you the best of luck but do you not have a NEC code book, it’s got the diameter in the book plus how many wires will go in every kind of pipe, flex, etc.

 

[jerryk1234]

.
Jerry I wish you the best of luck but do you not have a NEC code book, it’s got the diameter in the book plus how many wires will go in every kind of pipe, flex, etc.

I have an older one. Probably should get the latest. But does the book even have tables for a mixture of different sized wires?

 

[Megawatt]

I have an older one. Probably should get the latest. But does the book even have tables for a mixture of different sized wires?

Yes it does you will first have to find the size of your existing wires then find # 12 THHN copper wire. Exactly how many number 12 wires do you need and I know you are very intelligent being an engineer but I have worked with several electronics people and no disrespect but they didn’t even how to wire a stop- start button to make a motor run, but when it comes to electronics they was pretty dang sharp. I know you are but trust me the #12 wires will fit and according to the NEC one grounded conductor per branch circuit

 

[Megawatt]

Yes it does you will first have to find the size of your existing wires then find # 12 THHN copper wire. Exactly how many number 12 wires do you need and I know you are very intelligent being an engineer but I have worked with several electronics people and no disrespect but they didn’t even how to wire a stop- start button to make a motor run, but when it comes to electronics they was pretty dang sharp. I know you are but trust me the #12 wires will fit and according to the NEC one grounded conductor per branch circuit

Hey Jerry have they cut your power off yet. This is about the worst fire I have seen in California and I really feel for y’all good luck and god bless

 

[jerryk1234]

Hey Jerry have they cut your power off yet. This is about the worst fire I have seen in California and I really feel for y’all good luck and god bless

Not yet. But I don't trust them.

I just investigated that pipe between the main panel and the junction box. It's internal diameter is 1.5 inches. I don't know what is its type or trade size. It has 7 wires in it:
two black wires, .306" OD, 2 black wires .251" OD, one white wire .251" OD, one green wire .222" OD, and a green wire .164" OD.

So I need to figure out the trade size of the conduit and the trade sizes of the existing wires, and can then plug it all into the Southwire online calculator.

I tried poking a #14 solid that I had laying around from the panel down into the junction box - it went right through.

 

[Megawatt]

Not yet. But I don't trust them.

I just investigated that pipe between the main panel and the junction box. It's internal diameter is 1.5 inches. I don't know what is its type or trade size. It has 7 wires in it:
two black wires, .306" OD, 2 black wires .251" OD, one white wire .251" OD, one green wire .222" OD, and a green wire .164" OD.

So I need to figure out the trade size of the conduit and the trade sizes of the existing wires, and can then plug it all into the Southwire online calculator.

I tried poking a #14 solid that I had laying around from the panel down into the junction box - it went right through.

Jerry if you can push one wire through with no resistance then I don’t think you will have problems with your wires. It could possibly be tight, I don’t know how many wires you want to put in the panel but leave the # 14 in the pipe and use it to help pull the other wires in. Good luck

 

[jerryk1234]

... several electronics people and no disrespect but they didn’t even how to wire a stop- start button to make a motor run, but when it comes to electronics they was pretty dang sharp.

Yeah, I've met guys like that too. I was not an electronics engineer - rather a technician. My work was very hands-on. I became a software engineer in the early 80's. Back then, I built a 450-foot house addition with a permit. I did all the electrical myself - with the sole exception of moving the overhead service to the new box ( that I installed ). There was no way I was going to mess with those unprotected wires. I possibly went a little overboard with the sockets - I think I put one every four feet. And a cluster of sockets where I planned to put the TV set.

Back in that town, I always got the same inspector. He'd refer to me as "the homeowner with his own copy of the NEC".
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Jerry if you can push one wire through with no resistance then I don’t think you will have problems with your wires. It could possibly be tight, I don’t know how many wires you want to put in the panel but leave the # 14 in the pipe and use it to help pull the other wires in. Good luck

It looks like it will work. According to the Southwire calculator, the total fill is around 30% with the existing 7 wires and my 22 wires.

The wires are supplied with the transfer switch.

 

[Megawatt]

Yeah, I've met guys like that too. I was not an electronics engineer - rather a technician. My work was very hands-on. I became a software engineer in the early 80's. Back then, I built a 450-foot house addition with a permit. I did all the electrical myself - with the sole exception of moving the overhead service to the new box ( that I installed ). There was no way I was going to mess with those unprotected wires. I possibly went a little overboard with the sockets - I think I put one every four feet. And a cluster of sockets where I planned to put the TV set.

Back in that town, I always got the same inspector. He'd refer to me as "the homeowner with his own copy of the NEC".

Jerry I’m impressed that you can do this work and that’s where you learn and there is nothing no better than on the job training

 

[jerryk1234]

nothing no better than on the job training

Indeed. I've had fun learning all sorts of things. When we bought our house out of foreclosure, it had been vandalized. Among other things, the two central air conditioners had been mostly removed. I hit the books, took an EPA test, became a licensed HVAC technician, bought air conditioners and refrigerant on the Internet, pulled a permit, and installed my own ACs.

 

[Megawatt]

Indeed. I've had fun learning all sorts of things. When we bought our house out of foreclosure, it had been vandalized. Among other things, the two central air conditioners had been mostly removed. I hit the books, took an EPA test, became a licensed HVAC technician, bought air conditioners and refrigerant on the Internet, pulled a permit, and installed my own ACs.

Jerry if your that good on HVAC I need you at my house LOL have a good day