Author Topic: A/C Electrical Question  (Read 4559 times)

Offline Porcupinepuffer

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A/C Electrical Question
« on: April 18, 2015, 01:34:04 PM »
I'm into a week at Himark for the G2, and heard something new I didn't know. (which is a real shocker since I seem to know way too much)  The teacher was saying we're not allowed using more than 3' of liquid tight to and from the outdoor disconnect switch for the a/c condenser. He's saying if he we need more than that, we must then use ridgid pvc conduit. Is this true? I can picture many a jobs we've done with lots more than 3' of liquid tight. He also stated that we're not supposed to be running wiring through the liquid conduit with sheathing since conduit is made to have individual wires ran through it.

Once you shove wires that are already sheathed through a liquid conduit, you're potentially not allowing for enough heat dissipation that the wiring is rated for... ? This was something I've always wondered, but I've honestly never seen any installer un-sheath their wires when running it through the liquid tight for a/c installs that are old, or new.

It also brings up the second question about the liquid tight we use to protect the furnace from 5' from the floor. Since we're protecting it with liquid tight, would we not be required to have it unsheathed when passing it through the conduit?


Offline nash668

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Re: A/C Electrical Question
« Reply #1 on: April 18, 2015, 05:29:47 PM »
Did he mention it's in the new Electrical code? I heard him say the same half way through a class.

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Re: A/C Electrical Question
« Reply #2 on: April 18, 2015, 07:08:01 PM »
ESA Bulletin 26-24-1 says (See attachments),

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Question 2
Is liquid-tight flexible conduit permitted for the wiring of a central air-conditioner unit from inside a building to the disconnecting means and from the disconnecting means to the outdoor unit?

Answer 2
Yes.  Notwithstanding Rule 12-1302, liquid-tight flexible conduit shall be permitted to be installed in lengths greater than specified in the code for flexibility and simplicity of installation, provided that:
(1) The liquid-tight flexible conduit is supported as required by Rule 12-1308 using the refrigerant lines for support is acceptable.

I'm not sure if Rule 12-1302(2) applies to the 1/2" or 3/4" liquid tight that we use, but it says 1.5m or 5' can be used.  It says for 12 trade size conduit which I believe is 3/8".

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12-1302 Use of liquid-tight flexible conduit
(2) Runs of not more than 1.5 m of 12 trade size liquid-tight flexible conduit shall be permitted for the connection of equipment.

Rule 28-604(5) says a disconnect box can be 3m or 9' away from the air conditioner so I assume the liquid tight can also be 9' in length.

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28-604 Location of disconnecting means
(5) Motor disconnecting means for air-conditioning and refrigeration equipment shall be located within sight of and within 3 m of the equipment.

Offline Porcupinepuffer

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Re: A/C Electrical Question
« Reply #3 on: April 18, 2015, 09:47:50 PM »
Did he mention it's in the new Electrical code? I heard him say the same half way through a class.
I'm thinking he did. I'll have to inquire.

It also seems like it would make the electrical connections hazardous to use conduit if the condenser isn't on wall brackets. It would obviously shift with ground movement and break connections. He also mentioned not using the 90 degree elbow for the electrical connection to conduit at the furnace drop is not right and that the wire can still be damaged at the exposed section... I find the whole thing overkill to begin with. On the Quebec side, there is no additional mechanical protection of the wiring required... I guess someone in Ontario must have been piling up Samurai swords around their furnace and cut the nmd?
Then there's the new tamper proof plugs required in Ontario. Talk about ridiculous

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Re: A/C Electrical Question
« Reply #4 on: April 19, 2015, 08:43:57 AM »
I have seen thousands of furnaces installed with only plastic box connectors.  The space between the conduit and connector is exposed and still passes the ESA inspection.  I haven't seen one install in the last 6 years of new construction that had a fitting that seals the conduit tight to the furnace.

Download ESA Bulletin 12-19-11 - Here

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Question 6
What does the Code require where NMSC enters into short lengths of raceway for final connection to appliances such as furnaces, water heaters, central air conditioners, etc?

Answer 6
Rules 12-906(1) and 12-3022(1)(a)(b)(e) require bushings and/or box connectors to be used where the cable enters/exits a raceway or a cabinet. As an alternative, sharp edges shall be removed from the ends of the raceway and the cable shall enter/exit in a line with the raceway and shall be supported within 300 mm of that point in accordance with Rules 12-510.

Rationale 6
There are several rules that provide direction: Rule 12-906(1) requires the installation of a bushing or equivalent means to protect conductors from abrasion where they issue from a raceway; Rule 12-3022(3) requires a box connector where NMSC enters into an enclosure; and Rule 12-510 requires NMSC be supported within 300 mm of terminations. Acceptable equivalent protection to bushings is when sharp edges are removed from the ends of the raceway so that a raceway provides a smoothly rounded or flared entry for conductors and the cable enters/exits in a line with the raceway and is supported within 300 mm of end of raceway.

As per ESA Bulletin 12-19-11, the NMSC does not need to be unsheathed before it's installed in liquid-tight that serves as protective sleeving,

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The preferred method of compliance is to install a junction box and convert to armoured cable for the drop. Other methods include the use of raceways such as flexible metal conduit, EMT, rigid PVC, liquid tight flex, etc as protective sleeving over the NMSC where it drops to the appliance. Note that Rules 12-1500 and 12-1502 do not permit ENT to be used for this purpose.

NMSC is Non-Metallic-Sheathed Cable.  I can't find anything about using unsheathed wiring in liquid-tight to an air conditioner.  Even with a liquid-tight fitting at the disconnect box, there is still an opening inside that would allow heat to escape, and the end of the liquid-tight inside the house would also have an open end.  I have never unsheathed NMSC to install it in liquid-tight, but maybe that would make fishing the wire through easier.  I'm curious to know if there is a requirement to use only unsheathed cable inside liquid-tight used as a raceway.  I doubt the temperature inside the liquid-tight would exceed 90C.

ESA Rule 22-204(5) is the only thing I could find that might prevent the use of NMSC in liquid-tight and it only applies to wiring in buildings housing livestock or poultry,

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Rule 22-204(5)
Non-metallic-sheathed cable is not approved for installation in a continuous raceway system.

Regardless, Rule 22-204(5) has been amended,

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Rule 22-204(5) Non-metallic-sheathed cable shall be provided with mechanical protection, in the form of rigid steel or rigid non-metallic conduit or other suitable material to protect against damage from rodents, when
(a) installed in exposed locations less than 300 mm above any horizontal surface;
(b) installed in exposed locations on the side of floor joists or other structural members less than 100 mm below the upper surface of the floor joists or other structural members;
(c) run in attics; or
(d) run in concealed spaces.


Offline Porcupinepuffer

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Re: A/C Electrical Question
« Reply #5 on: April 19, 2015, 01:26:31 PM »
I'm impressed with your ability to dig up all this information. I'm used to being around people who think they no longer need to read any codebooks once they have a license... Then again, they're also the ones racking up back charges and infractions.