Can I Run Power 24 Feet Using Liquid Tight Flexible Conduit??

[William McCormick]

Sorry for getting a little off the OP's topic.

The 10KW heat is only 41.6 amp

Typical plate from a unit. The circled are the 10KW units. At 240 volt it is 54.9 amps max 60 amp breaker

Only needs 54.9 and since you can't install a 55 amp breaker because they do not exist code allows a 60 amp.

The #6 wire is good for the 54.9 amps it needs so no problem.



Here is a 10KW max breaker size 50 amp.

But you have the motor in the air handler that is supposed to be calculated at 2.5 times its amperage. I can assure you running the heaters that close to the wires capability will leave you with discolored hard insulation.

Sincerely,

William McCormick

[danielplace]

But you have the motor in the air handler that is supposed to be calculated at 2.5 times its amperage. I can assure you running the heaters that close to the wires capability will leave you with discolored hard insulation.

Sincerely,

William McCormick

Yea the name plates are all wrong. Lol. You really think they didn't figure in the blower motor load ?

I am sure they are running the wire so hot it is melting insulation in hundreds of thousands of homes with airhandlers with 10KW heat in them that were run in #6.

Really don't matter. They are that way and they work and have not heard of any mass fires in South Florida from airhandlers burning up or needed their wiring upgraded. Been working for 43 years and never had a single call to replace the #6 run to the airhandler.

https://forums.mikeholt.com/threads/...-heater.48352/

[danielplace]

William,
You keep mentioning 3 times the amp draw of the blower fan is needed but keep in mind that the airhandler blower motor would never need extra amps for starting it because it surely has it.

If running 10 KW heat, then it has #6 wire and 60 amps to start it. A little tiny 1/3-1/2 hp motor on 240 volt with #6's should start pretty well don't ya think.

The heat strips never come on until there is positive airflow from the blower. The manufacturer knows this so there is really no need for figuring extra in to start the blower motor.

[farmersammm]

I personally don't like the electric tape. Haven't even used it for years on vehicle 12v systems(which cause more fires than you can imagine)

I always worry about stray stands of wire eating through the tape, and contacting something.

[SweetMK]

I personally don't like the electric tape. Haven't even used it for years on vehicle 12v systems(which cause more fires than you can imagine)

I always worry about stray stands of wire eating through the tape, and contacting something.

So, do you use heat shrink??

[bigb]

I personally don't like the electric tape. Haven't even used it for years on vehicle 12v systems(which cause more fires than you can imagine)

I always worry about stray stands of wire eating through the tape, and contacting something.

Harbor Freight tape is good for one thing: pulling wire. For electrical use (rarely needed) it's something good like Scotch 33 and for engine use it's Engine Harness Tape. I can't imagine a lot of 12 volt fires unless folks are running unfused wires. I remember back in high school when vans were popular guys would wire up their stereos and amps without bothering with fuses, when that sh!t shorts out in a van full of carpet, bean bag chairs and wood paneling it's all you can do to just bail out, there's no stopping it unless you can get to the battery in a hurry and remove a cable. Back then cars had a lot of metal with sharp edges in the dash to short out wires.

[William McCormick]

William,
You keep mentioning 3 times the amp draw of the blower fan is needed but keep in mind that the airhandler blower motor would never need extra amps for starting it because it surely has it.

If running 10 KW heat, then it has #6 wire and 60 amps to start it. A little tiny 1/3-1/2 hp motor on 240 volt with #6's should start pretty well don't ya think.

The heat strips never come on until there is positive airflow from the blower. The manufacturer knows this so there is really no need for figuring extra in to start the blower motor.

We only put fifty amp breakers to number six wire here that is the code.

The heat strips turn on first and then the sequencer turns on the fan.

Sincerely,

William McCormick

[William McCormick]

Most mini splits use a cable designed & listed for the purpose to interconnect outdoor to indoor unit. It's a listed (UL) paired unit, so no additional overcurrent protection for the indoor unit beyond that provided by the heat pump pair manufacturer. Indoor unit gets its power from outdoor, & might be fused at 30 amps.

I can't say I've seen electric heaters in the outdoor, or indoor units except old machines that used them to boost air heat in very cold weather. We had numerous phone company buildings in the 1970s had this arrangement. These had either two breakers inside the outdoor unit as disconnect & overcurrent, or a 6 circuit raintight breaker panel on the wall of the building. Aside from that, heat pumps only became practical in our climate in the last ten years.

You cannot run that NM stranded four wire outside though, so you need to cover it with seal tight anyway. And some inspectors want the liquid tight to be terminated in a box inside. So it becomes a nuisance either way. If it is available I get the rubber coated MC cable. But lately they do not even have the NM stranded four wire much less the rubber coated MC cable.

The control cables are coming 16/3 now, so that you can pull them through 1/2” liquid tight ahead of time and then just pull it all through the house rather nicely.

Sincerely,

William McCormick

[bigb]

We only put fifty amp breakers to number six wire here that is the code.



Sincerely,

William McCormick

That would be code for NM #6 from the 60C column (required), 55 amps. #6 THWN/THHN/XHHW etc. is allowable to start from the 75C column which starts you at 65 amps before any de-rating. We generally run #8 THWN-2 in pipe for 50 amps.

[William McCormick]

That would be code for NM #6 from the 60C column (required), 55 amps. #6 THWN/THHN/XHHW etc. is allowable to start from the 75C column which starts you at 65 amps before any de-rating. We generally run #8 THWN-2 in pipe for 50 amps.

Having done a lot of HVAC I have seen too many units melt or toast wiring because they were low on freon and were starting and stoping for several days. I have even seen number four wire burn off its insulation while not tripping the breakers feeding it, from the compressors starting and stopping. It was that one job in particular that made me think that it is up to the electrician not just the codes.

Sincerely,

William McCormick

[bigb]

Having done a lot of HVAC I have seen too many units melt or toast wiring because they were low on freon and were starting and stoping for several days. I have even seen number four wire burn off its insulation while not tripping the breakers feeding it, from the compressors starting and stopping. It was that one job in particular that made me think that it is up to the electrician not just the codes.

Sincerely,

William McCormick

Of course it's always up the the electrician, codes are just a minimum standard. My reason for the post was because you said #6 was code for 50 amps and since that's not the whole story I wanted to put the whole story out there for those who are interested, a lot of folks read these threads and the info should be accurate. It wasn't to tell you what size wire to use, that's your decision.

[Sberry]

See,,, if a guy would have answered this outright on post 3 and not incited it just a touch along the way it wouldnt have made 3 pages.

[William McCormick]

See,,, if a guy would have answered this outright on post 3 and not incited it just a touch along the way it wouldnt have made 3 pages.

You can run liquid tight even in commercial buildings if you secure it along the way. It is just that it is not the A job. Sometimes there is no choice or other choices would be more dangerous. But in a home if you do not have to run any NM cable you are better off in my opinion. Steel armored cable stops the EMF around the wires that has been proven to cause cancer.

But best practice is not to plan on liquid tight. You cannot easily pull wire through it at all.

Sincerely,

William McCormick

[Willie B]

You cannot run that NM stranded four wire outside though, so you need to cover it with seal tight anyway. And some inspectors want the liquid tight to be terminated in a box inside. So it becomes a nuisance either way. If it is available I get the rubber coated MC cable. But lately they do not even have the NM stranded four wire much less the rubber coated MC cable.

The control cables are coming 16/3 now, so that you can pull them through 1/2” liquid tight ahead of time and then just pull it all through the house rather nicely.

Sincerely,

William McCormick

I think a mini split must be a different animal than those I've seen. Those being installed here are heat pumps/air conditioners. The outdoor unit contains the compressor, the indoor unit has no heavy electrical load.

You are correct, it is unacceptable to use NM-B in wet locations. There is a product sold at any wholesaler where heat pumps are sold listed for the interconnect of outdoor & indoor units.

As for supply, inspectors vary as to supplying the disconnect with NM-B. I'm more likely to run PVC through the house sill with female adapter & non watertight connector. I strip the jacket & paper off the portion inside the conduit. I haven't had an inspector object to the practice. I've discussed it with one inspector, his answer was you should be using THWN(-2) from indoor to disconnect outdoor.

It's a concern anywhere you supply any load in a wet location. Light fixtures for example, to comply with the letter of code, must you substitute UF-B for NM-B? You are entering a wet location.

[danielplace]

I think a mini split must be a different animal than those I've seen. Those being installed here are heat pumps/air conditioners. The outdoor unit contains the compressor, the indoor unit has no heavy electrical load.

You are correct, it is unacceptable to use NM-B in wet locations. There is a product sold at any wholesaler where heat pumps are sold listed for the interconnect of outdoor & indoor units.

As for supply, inspectors vary as to supplying the disconnect with NM-B. I'm more likely to run PVC through the house sill with female adapter & non watertight connector. I strip the jacket & paper off the portion inside the conduit. I haven't had an inspector object to the practice. I've discussed it with one inspector, his answer was you should be using THWN(-2) from indoor to disconnect outdoor.

It's a concern anywhere you supply any load in a wet location. Light fixtures for example, to comply with the letter of code, must you substitute UF-B for NM-B? You are entering a wet location.

In residential a wall or ceiling mounted light fixture is perfectly fine fed with romex. No house needs any UF for anything unless you are wiring outside of the structure. Then it still doesn't. UF is garbage. Do it right in PVC and THHN outdoor or in ground. You can usually even go down a line cover or a pipe down out of the soffit with romex as long as stopping before the ground. Not likely any inspector is going to require UF for any of that. Dry location in that pipe above ground only coming down to terminate. Don't suggest you run any PVC or EMT on the outside walls and put romex in it. That may very well get turned down.

Usually your installing a light box flush in the wall for 90% of all fixtures so your never even in wet location to begin with.

The immediate inside of a wall or ceiling mounted fixture is arguably not a damp location. The fixture is in the damp location but since it is designed as such the inner compartment you are entering is still dry location or exception made however you want to call it because it is ok to do for sure.

Nobody including the contractors/inspectors for cities/counties want a bunch of nasty *** UF up in all the switch boxes that is for certain when just not necessary to add that expense for nothing.

Millions of houses have and are getting wired with just romex. Lots of outside lights all over. Certainly a disconnect for the A/C condensor. The Carflex/Sealtite needs THHN.

As for stripping off the sheath some inspectors do not like that. Most don't look or care. Really should never be a need to do that. Sure it makes it easier to push it in but the sheath is part of the cable and the EMT or PVC is just protection for the cable not a replacement for the sheave on the cable. It needs to stay intact up to the box it is entering.

The interconnect wire is part of the mini-split package in 90% of the units sold. You only feed the outdoor unit with a circuit and it feeds back into the airhandler. A good amount of them are DC inverter units. Both the compressor and even the air handler on many of those will be DC too.

The quality mini splits I have seen used in many IT rooms for buildings are Mitsubishi and they are all standard 240 volt unit at both ends even though the condenser gets the input circuit and then it feeds back out of terminals of the condenser to feed out to the air handler. There is no heat or reverse cycle. Strictly a/c units.

[bigb]

In residential a wall or ceiling mounted light fixture is perfectly fine fed with romex. No house needs any UF for anything unless you are wiring outside of the structure. Then it still doesn't. UF is garbage. Do it right in PVC and THHN outdoor or in ground. You can usually even go down a line cover or a pipe down out of the soffit with romex as long as stopping before the ground. Not likely any inspector is going to require UF for any of that. Dry location in that pipe above ground only coming down to terminate. Don't suggest you run any PVC or EMT on the outside walls and put romex in it. That may very well get turned down.

Usually your installing a light box flush in the wall for 90% of all fixtures so your never even in wet location to begin with.

The immediate inside of a wall or ceiling mounted fixture is arguably not a damp location. The fixture is in the damp location but since it is designed as such the inner compartment you are entering is still dry location or exception made however you want to call it because it is ok to do for sure.

Nobody including the contractors/inspectors for cities/counties want a bunch of nasty *** UF up in all the switch boxes that is for certain when just not necessary to add that expense for nothing.

Millions of houses have and are getting wired with just romex. Lots of outside lights all over. Certainly a disconnect for the A/C condensor. The Carflex/Sealtite needs THHN.

.

There is a code reference for wire that is passed thru an exterior masonry wall, or an earthen wall. Here we have a lot of masonry and mud adobe homes and we are required to run UF to the exterior boxes when they are in masonry or mud adobe, we also are required to sleeve it in PVC where it goes thru the block or the adobe. We also have a code amendment regarding earthen construction and burnt adobe construction (which is baked blocks with no hollow cells), we are allowed to run UF in the mortar joints keeping it the required distance from the finished surface. We are also allowed to run UF in mud adobe. No NM allowed in either of those 2 instances. In more recent years the requirement for wall insulation has made it necessary for new burnt adobe construction to have wood fur outs inside for the insulation which has made wiring them 10 times easier, the older ones are a single wall of 8x8x16 baked adobe blocks, sometimes bare on both sides and sometimes plaster applied directly to the inside surface, no insulation at all. Wiring one of those is not fun and required you to be on site as the masons built the walls.

[Willie B]

In residential a wall or ceiling mounted light fixture is perfectly fine fed with romex. No house needs any UF for anything unless you are wiring outside of the structure. Then it still doesn't. UF is garbage. Do it right in PVC and THHN outdoor or in ground. You can usually even go down a line cover or a pipe down out of the soffit with romex as long as stopping before the ground. Not likely any inspector is going to require UF for any of that. Dry location in that pipe above ground only coming down to terminate. Don't suggest you run any PVC or EMT on the outside walls and put romex in it. That may very well get turned down.

Usually your installing a light box flush in the wall for 90% of all fixtures so your never even in wet location to begin with.

The immediate inside of a wall or ceiling mounted fixture is arguably not a damp location. The fixture is in the damp location but since it is designed as such the inner compartment you are entering is still dry location or exception made however you want to call it because it is ok to do for sure.

Nobody including the contractors/inspectors for cities/counties want a bunch of nasty *** UF up in all the switch boxes that is for certain when just not necessary to add that expense for nothing.

Millions of houses have and are getting wired with just romex. Lots of outside lights all over. Certainly a disconnect for the A/C condensor. The Carflex/Sealtite needs THHN.

As for stripping off the sheath some inspectors do not like that. Most don't look or care. Really should never be a need to do that. Sure it makes it easier to push it in but the sheath is part of the cable and the EMT or PVC is just protection for the cable not a replacement for the sheave on the cable. It needs to stay intact up to the box it is entering.

The interconnect wire is part of the mini-split package in 90% of the units sold. You only feed the outdoor unit with a circuit and it feeds back into the airhandler. A good amount of them are DC inverter units. Both the compressor and even the air handler on many of those will be DC too.

The quality mini splits I have seen used in many IT rooms for buildings are Mitsubishi and they are all standard 240 volt unit at both ends even though the condenser gets the input circuit and then it feeds back out of terminals of the condenser to feed out to the air handler. There is no heat or reverse cycle. Strictly a/c units.

I typically work with one State Electrical Inspector for a period of years. I've outlasted several changes of inspector thus far.
All of the inspectors have disagreed with your position that a flush mounted box is not in a wet location. When the fixture mounted on it need to be listed for wet or damp locations, they consider the box to be wet location. None have insisted on UF, or other wet location listed supply for flush mounted boxes. All urge a proper job of sealing the fixture to exclude water. All encourage techniques to keep drips from causing corrosion in the wire nuts & drip loops, with wire nut pointing up. I don't believe this appears in code, it's only good practice. I see all the time a fixture properly installed, but damaged to allow water into the box.

All inspectors I've dealt with agree a surface mounted wet location box & any outdoor wiring must be suitable for wet locations. The concept of running NM-B cable through a outdoor siding, into the back of a disconnect, or other surface mounted enclosure, is subject to the approval of the Authority Having Jurisdiction.

My practice is to assume the caulking I place between siding & box might fail. I prefer to exit the siding with PVC conduit, or sealtite. I enter the bottom of the box (disconnect) . If supplied by NM-B I strip jacket & paper from it before entering the conduit. I use a female thread adapter & NWT connector inside the building to pass it through.

[Sberry]

I see all the time a fixture properly installed, but damaged to allow water into the box.

I aint out there every day but have seen more than a couple rotted boxes water gets in. NM-B seems is ran to outdoor boxes all the time thru walls. Inside that fixture box is not sposed to be a wet location. But,,, the listed wet covers are mostly pitiful junk, I put flashing over that stuff. Nothing in code says a guy cant add extra.

[bigb]

I don't know why so many people use caulk and seal all around a box and end up trapping water in. I only caulk the top and sides and if exposed to direct rain I cut a slot in the bottom of the gasket.

[Willie B]

I don't know why so many people use caulk and seal all around a box and end up trapping water in. I only caulk the top and sides and if exposed to direct rain I cut a slot in the bottom of the gasket.

The big book specifies required drain holes. If memory serves they specify a range of acceptable hole sizes.

[William McCormick]

Yea the name plates are all wrong. Lol. You really think they didn't figure in the blower motor load ?

I am sure they are running the wire so hot it is melting insulation in hundreds of thousands of homes with airhandlers with 10KW heat in them that were run in #6.

Really don't matter. They are that way and they work and have not heard of any mass fires in South Florida from airhandlers burning up or needed their wiring upgraded. Been working for 43 years and never had a single call to replace the #6 run to the airhandler.

https://forums.mikeholt.com/threads/...-heater.48352/

You guys have square wave down there, and probably 208 that can make the difference. I used to manufacture three phase heating equipment and the units down there ran much cooler than the units up here in NY.

You guys only get 8,666 watts out of 10,000 watt strip heaters. And they are only drawing 41.6 amps. Our 8,000 watt strip heaters draw the same 41.6 amps.

Sincerely,

William McCormick

[Norcal01]

The 2020 NEC requires a GFCI for A/C condensing units, and caused a s*** storm because a number of units do not play well with GFCI's & were never tested with them because UL standards do not require them to be, all because a unit was not properly grounded a fault occurred & some kids were electrocuted, while always sorry when people are injured or die, when the work done failed to meet basic standards, the answer is not to add to the requirements, the doofus who hooked it up wrong needs some prison time at hard labor.

[danielplace]

The 2020 NEC requires a GFCI for A/C condensing units, and caused a s*** storm because a number of units do not play well with GFCI's & were never tested with them because UL standards do not require them to be, all because a unit was not properly grounded a fault occurred & some kids were electrocuted, while always sorry when people are injured or die, when the work done failed to meet basic standards, the answer is not to add to the requirements, the doofus who hooked it up wrong needs some prison time at hard labor.

They have have just completely lost their minds with every circuit of residential requiring AFCI and/or GFCI even on the equipment, the GDO, everything.

[Willie B]

There is always competition among electricians. One electrician ignores the new code changes, gets away with it. Next electrician complies with the rules, costs more. Most building owners, ALL general contractors choose the low price.

In VT there is no inspection of private homes. It seems to me any work that is inspected, inspectors look the other way for some electricians.

[Sberry]

We are under inspection for all of it,,,, they really lean on residential and probably with good cause.