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

[bigb]

As far as the sealtight you can run it as far as you want so long as you secure it at the minimum required intervals. As mentioned, it will look unprofessional and will be impossible to pull wire into it. Greenfield or Smurf would be better, and EMT best. Or Romex. The six foot rule comes into play for flexible fixture whips in grid ceilings, they are limited to 6 feet before they have to be secured. The other six foot rule applies to using metallic sealtight for a grounding conductor, the limit used to be six feet but now that all outdoor conduit requires a grounding conductor to be included it is no longer applicable.

[Willie B]

There are support rules for NMLT. Much like conduit it should have support near each end, then 3' or six feet depending on circumstance. You talk of two circuits, one being 60 amps. That'll take big NMLT flex. At least four current carrying conductors, I think you're talking 80% load.
Not how I'd do it. I'd favor a feeder to an outside breaker panel. Then a breaker feeding each load. I'm still unclear if the 60 amp heater is a part of the heat pump, or its own load.

30 years ago it was considered VT didn't have enough heat in the air for a heat pump to work when it was very cold. I never wrapped my brain around it, but somehow supplementing air heat with a bit of electric resistance heat made it work. I no longer hear it mentioned. I'm not clear if it is a heat pump plus heaters, or a heat pump OR heaters.

[tadawson]

Can't speak to this specific system, but all I have seen have a "crossover" temp range when the electric runs with the compressor, si ce the heat from the compressor/pump does not just quit, but falls off as the temp decreased. My system, for example, has a dual speed compressor as well as two stage electric, so stages electric in as needed after going to high compressor. Below a certain temp, the compressor will lock out to avoid excessive energy use and potential damage, leaving you 100% electric.

[William McCormick]

It is most often seen with electric heat in the airhandler and a condensing unit. My point was it is not automatically a problem to have the airhandler and a condensing unit on the same breaker/circuit. The high load will only be in one unit at a time. The airhandler fan is always part of the load but not the heat strips and compressor at once so it is all good.

Yea his situation is different heat pump and heat strips in the airhandler. Both high draw. Both can run at same time. Not a coincidental load.

They can never be on the same circuit, because they both run together for AC. In the winter some heat pumps run with the strip heaters so again never can the outdoor unit be run on the same wire. It is done all the time and it is not to code and is not safe. The air handler could be on fire and no one knows what breaker shuts it off. And because they usually feed the air handler that is supposed to get a max 25 amp breaker with the sixty amps in the outdoor disconnect it is very wrong.

Sincerely,

William McCormick

[William McCormick]

There are support rules for NMLT. Much like conduit it should have support near each end, then 3' or six feet depending on circumstance. You talk of two circuits, one being 60 amps. That'll take big NMLT flex. At least four current carrying conductors, I think you're talking 80% load.
Not how I'd do it. I'd favor a feeder to an outside breaker panel. Then a breaker feeding each load. I'm still unclear if the 60 amp heater is a part of the heat pump, or its own load.

30 years ago it was considered VT didn't have enough heat in the air for a heat pump to work when it was very cold. I never wrapped my brain around it, but somehow supplementing air heat with a bit of electric resistance heat made it work. I no longer hear it mentioned. I'm not clear if it is a heat pump plus heaters, or a heat pump OR heaters.

The air handler has strip heaters in it. And if they are the right ones for his unit they will also have a molex that feeds the control board.

I always put a disconnect at the air handler with strip heaters as well but I put a disconnect with an external throw. If the air handler is just for AC then I put in a two pole switch in a metal box and attach it to the air handler, or near it, and bond it at the box and in the air handler.

Sometimes the plug in disconnects can throw some hot metal so I do not use them inside. If the job will bear it I put disconnects with an external throw for the outside unit as well.



Sincerely,

William McCormick

[William McCormick]

There are support rules for NMLT. Much like conduit it should have support near each end, then 3' or six feet depending on circumstance. You talk of two circuits, one being 60 amps. That'll take big NMLT flex. At least four current carrying conductors, I think you're talking 80% load.
Not how I'd do it. I'd favor a feeder to an outside breaker panel. Then a breaker feeding each load. I'm still unclear if the 60 amp heater is a part of the heat pump, or its own load.

30 years ago it was considered VT didn't have enough heat in the air for a heat pump to work when it was very cold. I never wrapped my brain around it, but somehow supplementing air heat with a bit of electric resistance heat made it work. I no longer hear it mentioned. I'm not clear if it is a heat pump plus heaters, or a heat pump OR heaters.

And I always put in a convenience outlet if I wire in the condenser. The electricians forget to do it a lot and it is code. For lights and vacuum pumps it is nice to have one. Other wise the HVAC guy runs 100 feet of extension cord to an outlet that has no ground or his extension cord ground prong breaks off and his vacuum pump casing is energized by the hot wire in the extension cord.

Sincerely,

William McCormick

[William McCormick]

He can't because both can have high draw at airhandler with heat strips and the heat pump that runs too.

Not for heat pumps systems.

The standard split unit system with electric heat in air handler they will often hit the air handler first with the heat strips at enough amperage for that unit #10's/30 for 5 KW #8's/45 for 7.5 KW or #6's/60 for 10 KW then you can split off that line and feed a smaller or even similar sized load/condenser compressor. Usually the compressor is less than needed for electric heat.

They allow you to reduce the wire at the airhandler too simply because the compressor can not draw more than it uses or is fused at. Your could have #6's feeding a 10 KW air handler and then reduce to #10's and head out to a condensing unit and fuse it at 30 amp or less(or whatever size the condensing unit needs)all running off a single 60 amp in the panel. It does not need matching protection to the wire size ahead of that wire reduction it is only needs the proper size fuses feeding the equipment of the same size draw.

You cannot run #6 for 10,000 watts of strip heat and the indoor fan motor because you have to allow 2.5 times the amperage for the fan motor. You would be at fifty amps just for the strip heaters and the blower motor. You can only do 8,000 watts of strip heat on number six wire. And this leaves nothing to power the outdoor unit. If guys are doing that they are doing it wrong.

Sincerely,

William McCormick

[William McCormick]

I donjt know one piece from another but isnt the minimum circuit and max breaker listed? If its got a max obviously cant be part of a larger combined circuit???

You have to see the mini splits, most come with SJO cord to connect the outdoor unit to the indoor units. And they leave you no place to ground at the indoor unit. So people just run SJO cord which is extension cord wire to carry 240 volts to the indoor units through the walls.

The Mitsubishi units have a place to land MC cable.

Sincerely,

William McCormick

[Willie B]

You have to see the mini splits, most come with SJO cord to connect the outdoor unit to the indoor units. And they leave you no place to ground at the indoor unit. So people just run SJO cord which is extension cord wire to carry 240 volts to the indoor units through the walls.

The Mitsubishi units have a place to land MC cable.

Sincerely,

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.

[bigb]

Correct me if I am wrong but on a mini split I thought the indoor units were 24V DC.

[Willie B]

Correct me if I am wrong but on a mini split I thought the indoor units were 24V DC.

I believe 240 volt. Mostly there are valves & relays, I believe they work at lower voltage. The blower is line voltage & they all are built across the pond. Most I've seen do not use a neutral conductor 240 only.

[danielplace]

You cannot run #6 for 10,000 watts of strip heat and the indoor fan motor because you have to allow 2.5 times the amperage for the fan motor. You would be at fifty amps just for the strip heaters and the blower motor. You can only do 8,000 watts of strip heat on number six wire. And this leaves nothing to power the outdoor unit. If guys are doing that they are doing it wrong.

Sincerely,

William McCormick

William,
We are talking a normal split A/C system. Not a heat pump system.

The heat strips never run if the condenser is running. Heat or Cool not both EVER. It can not run both at once.
Cool fan/compressor Heat fan/heat strips. Eh ?

I have been doing this for a really long time. Ran power for many 10 KW air handlers in that time. We run #6 to them all.
Even if it was in Romex for residential work.
In normal split a/c system the heat strips are not on if the outdoor unit is on. Heat is the strips cool is the condenser. Eh ? The outside doesn't draw anything when in heat mode with heat strips running. In cool the airhandler fan runs and the condenser so no problem no where.

10KW is most common unit installed in 3 BR 2 Bath houses. We never ran any 4-2 to anything for certain. The heat strips I believe on some are actually 9.6 KW for a total with fan just able to use #6 on a 60 amp breaker. The #6 on 60 amp is installed in every installation I have ever seen using 10 KW airhandler and I have seen a bunch.

The non coincidental wiring method of tapping off the airhandler power is very common but not my preferred way of doing it but many hundreds of thousands of them are wired that way all over. The airhandler and the condenser sure as heck share the same circuit safely legally and properly with zero reasons for any issues related to the way it is fed.

[Willie B]

I've seen 10? 25 amp breakers in 43 years as an electrician. Never seen A 25 amp GFCI. If you have your heart set on a GFCI, I suggest a fusible, or circuit breaker equipped raintight (NEMA3R) disconnect at the outdoor unit. Use a QO230GFI in the breaker panel.
Or run a feeder (#4 SER) to a NEMA3R panel near the machine.

I don't see the logic of GFCI for a fixed machine. Equipment ground is assured through many precautions I bet you will not use that ARE required by code.

Make that 53 years as an electrician. I don't count pretty much too good.

[Sberry]

When they say that it does say max breaker, doesnt mean its the actual. If it was mine it would be 20 if it worked ok and worry about it later.

[danielplace]

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.

[SweetMK]

Make that 53 years as an electrician. I don't count pretty much too good.

If my math is right, that equates to the year 1969,,
1969 is the year I started HVAC technical school at Connelly Tech in Pittsburgh PA,,
(I just Googled it, the building is now called the Energy Innovation Center,,,,,,,)

Technical school was the only school exemption to being drafted,, so technical school it was,, two year Associates Degree.
The US Navy thought I needed 34 weeks of Welding School, so I never went to work using my HVAC training, other than a year of co-op work/school time.

The only reason HVAC was selected at the technical school was that one of my friends father owned a HVAC business, and said he would hire us if that was our education choice.
That guy passed away, and the HVAC business closed before we finished school. Alcohol was hard on MANY fathers back in the 1960's,,,

[Sberry]

I read most of it, good. I can barely count to 10 but the outdoor might need to be on a current limited circuit, might be able to wire it all together if there was additional protection and heavy enuf wire. We build our own coolers before and I simply add a 6 space panel to the stand alone units. I wired something upm the other day and took a breaker and 2 spaces, wasnt a bad thing but right after I did it, oh shate, could have been easier and conductors were rated for it.

[SweetMK]

Just so everyone can say they have seen one "in the wild",, here is the pic of my 25 amp breakers.
I noticed a significant weight difference,, the GFCI breaker weighs almost exactly double the weight of the regular breaker.

The GFCI breaker is sold by "DDA Distributors, LLC"
When the package arrived, it is printed "ZORO" in several locations
The address on the package turns out to be Graingers Warehouse, 701 Grainger Way, Minooka IL.

How many layers deep do these companies have to hide to avoid lawsuits??

[SweetMK]

I JUST noticed,, I get to use my ROBERTSON screwdriver,, I think this will be the third time I have used Robertson, since discovering it,,

[Sberry]

It aint that,,, its every step someone has figured how to add something to the price. So much anymore is delivered to the vendor in a white box, can change or add a sticker depending on who its sold thru. On slower moving items maybe even warehouse only a few sold by several vendors.

[Sberry]

Say there is a cAll foir a dozen a day in a city, could offer ift for sale by 100 different stores, might even stock it at a couple like auto parts chain does and yank it back if its ordered elsewhere.

[Sberry]

I see a regional outfit that has 3 or 4 deliveries from a main to their stores a day. I can see them stopping by HF at any given time to pick a tool or even stock some.

[bigb]

I JUST noticed,, I get to use my ROBERTSON screwdriver,, I think this will be the third time I have used Robertson, since discovering it,,

That's so you can use your torque screwdriver on it.

[SweetMK]

That's so you can use your torque screwdriver on it.

I do not have one of those,,, yet,, I only have a calibrated WRIST!!

[William McCormick]

William,
We are talking a normal split A/C system. Not a heat pump system.

The heat strips never run if the condenser is running. Heat or Cool not both EVER. It can not run both at once.
Cool fan/compressor Heat fan/heat strips. Eh ?

I have been doing this for a really long time. Ran power for many 10 KW air handlers in that time. We run #6 to them all.
Even if it was in Romex for residential work.
In normal split a/c system the heat strips are not on if the outdoor unit is on. Heat is the strips cool is the condenser. Eh ? The outside doesn't draw anything when in heat mode with heat strips running. In cool the airhandler fan runs and the condenser so no problem no where.

10KW is most common unit installed in 3 BR 2 Bath houses. We never ran any 4-2 to anything for certain. The heat strips I believe on some are actually 9.6 KW for a total with fan just able to use #6 on a 60 amp breaker. The #6 on 60 amp is installed in every installation I have ever seen using 10 KW airhandler and I have seen a bunch.

The non coincidental wiring method of tapping off the airhandler power is very common but not my preferred way of doing it but many hundreds of thousands of them are wired that way all over. The airhandler and the condenser sure as heck share the same circuit safely legally and properly with zero reasons for any issues related to the way it is fed.

Until someone wires in or programs their own nest and both are running together. It is just a bad idea an accident waiting to happen.

Sincerely,

William McCormick