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Thread: Wiring for a Mini-Split AC system

  1. #31
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    If this SJ cable is what looks like a heavy duty vacuum cleaner cord, then this is cord, not cable. Generally, cord can not be used for permanent premises wiring, and that is why you can't find staples for cord. If you were jumping between two pieces of machine, and that is what the instructions said to use, you may be able to get away with it (especially if there was a plug on the end or the distance was real short). But when you run it in or on the wall, it becomes premises wiring and must be a listed type of wire or cable for that application.

    Is there any reason why you just can't run a 1/2" flex conduit the whole way and pull individual #14 wires through that conduit (typically the minimum size wire you can use)? Are there installation directions for this unit that are intended to apply to the US? Did they say to use a cord type conductor?

    This16ga SJ cord isn't correct from the disconnect to the compressor. This must be #14 wire minimum and a wet area cable (SE, UF) or individual conductors with a W in them (THWN). The remaining wiring is kind of gray because you're going between pieces of equipment, but you still need to use an NEC legal wiring method if running this wiring in or on the building.
    Mark
    Kent, WA

  2. #32

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    Here's where I'm at so far


    I spoke to the company and they told me that this cable is usually up to code. I figured I'd post a picture here and call for the first inspection. There's a 15 amp breaker in the non-service panel that I installed inside the garage. The wires run in the Non-Metalic conduit. Here's the full text of what's written on the two 16 gauge wires, the 14 gauge is similar.
    (UL) SJTW VW - 105C 300V E230919 16AWGX3C
    or
    (UL) SJTW FT2 105C 300V 16AWG3C (hope I got that right).

    To protect the wires going into the house I used a pair of the plastic conduit connectors (overkill I know, but I didn't want to run back to the store). The orange is 10/2 NM that I ran from the NSP. The 14 runs only from the disconnect to the compressor. The 16 gauge wires and the thin gray wire are running from the compressor to the air handler.I'd write more but the family is running to services. Any suggestions before I call the inspector?

    Thank you,
    Dan

  3. #33
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    Don't call him yet....

    The gray wire is low voltage??? If so, it can't share the same raceway as the higher voltage (120/240) stuff.

    The SJTW is cord, not building wire. It is not a permitted wiring method to interconnect things. One of the reasons, is cord isn't necessarily fireproof (it may be, but it hasn't been tested as such). It may be allowed from the disconnect to the compressor (but why use cord when you already have a whip and can use the legal minimum #14 conductors?).
    Mark
    Kent, WA

  4. #34

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    So you're saying that the company sent me something that is completely wrong? That the 14 gauge SJ may be allowed for the 8' from the disconnect but even that could be wrong?

    This is very disheartening. The wires they included are each color coded, 25' long, with individual colors that relate to the wiring diagrams on both ends so they obviously thought these were fine to use. What am I supposed to do now?

    I understand what you're saying, but I'm really hoping you're wrong (nothing personal ). I really don't want to take everything down and start over, but if I have to then I will.

    Slooo,
    What type of systems have you installed? What wires came with them?

    Thank you,
    Dan

  5. #35
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    Manufacturers do all kinds of things that make our life hard. They say things are code required that aren't. They say to do things the code doesn't allow. They totally neglect technical issues in the instructions that are code relevant. They'll say "conforms with all electrical codes", like they could know every local code nuance across the entire 50 states.

    You can try the inspection and hope he either doesn't care, doesn't know, or isn't picky. If he balks, you can show him the manufacturers instructions and hope he considers this all an inter-related system and meant to be used this way by the manufacturer. I thought you bought this SJ cord to use. If it was supplied with the equipment, that will certainly help your argument.

    Did the manufacturer say it was OK to install that small grey cable in the same raceway as the power supply cable (or even the SJ cable)? Does that grey have a voltage rating on the jacket that says 300V or higher?

    A letter-of-the-law inspector may not allow this to be installed this way (SJ cable run in premises raceways). If the inspector is wavering, but wants it changed, it probably won't cost for a second inspection (if that's any condolence).
    Last edited by suemarkp; January 28th, 2007 at 04:00 PM.
    Mark
    Kent, WA

  6. #36
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    I have worked with Fujitsu units, so the gray wire is new to me. What brand is your split system? If you could, try to take good pictures of the schematic so I can take a look at it. Fujitsu has no transformers, so you might luck out and not have any transformers. If that's the case, you should be good to go. If it's not, you can't run low voltage with high voltage. Reson being is low voltage is usually control voltage and is user safe. If you have an arc and it attaches to the high voltage, you have a saftey issue with people who might try to work on there own units. I have seen it happen before. I was working on a home roof top unit and the owner ran all the t-stat wire with the 240 volt wire. The t-stat fried so I checked the voltage of the wires at the t-stat and I had 120 volts to common. Turned out one of the wire nuts failed and welted to the white (heating) wire. Blew the transformer, t-stat, control board, and the gas valve. A little short cut cost him $600 to repair.

  7. #37

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    The first picture I'm including is of the gray wires label. I think it's for defrosting the outdoor unit. It is labeled 300V so it's ok to leave in that conduit, right? Since we're talking about it, it is too long so I was planning on coiling it inside the wall. It has plastic clips at both ends so I can't cut it. If there's any issues please let me know.


    Here's two pictures of the wiring diagram. The first is from the plate and the second is from the manual.




    And, here's one of the plate just in case.


    All the cables except for the 10/2 I ran from the NSP were supplied with the mini-split kit. If I was going to run individual THHN wires that does make thing a bit more difficult because there are clamps inside the covers on the air handler and the compressor. And, it's more difficult because the cables were color coordinated. For THHN I'll need some different clamps???

    Here's a picture from the air handler (the inside component). On the left side are the two SJ cables and you can see the clamp. Wouldn't that indicate that I should stick with the SJ???


    I am curious, Slooo what wires do the Fujitsu units come with? The system is a Celiera from http://www.ac-world.com/proddetail.p...1GW/GX1a&cat=9 .

    Thanks again,
    Dan
    Last edited by Daniel J; January 29th, 2007 at 11:54 AM.

  8. #38
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    The Fujitsu units only require 6 wires between the indoor and outdoor unit. Where do the wires for the gray line terminate on the indoor and the outdoor unit. From what I see, it looks like the gray wire goes to the thermister which would make this a low voltage wire.

    Also, make sure you use refrigerant seal for your flared fittings. This system runs on R410 and runs at high pressures. last thing you want is a flare to leak.
    Last edited by sloooo; January 29th, 2007 at 12:38 PM.

  9. #39
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    This is getting confusing enough that you may want to talk to your inspector before he comes out to determine what he thinks the issues are. In rereading some of thse code, I'm not sure how to handle the grey wire.

    If the grey wire is low voltage, it may be able to go with the SJ's to the air handler (and I'd relocate it through that raceway or nipple if that is easy to do). It may even be able to stay with the orange 10-2, as it is associated with the load the 10-2 is powering. These nipples may even be a "sleeve" and not a raceway depending on what the other end is like (all this cable and cord is run in the walls without a conduit, right?).

    What is missing is the classification of the signals on each cable (power, control, power limited class 1, 2 or 3), and knowing if premises rules must be applied to all wires of an appliance that is in two parts spread apart. The inspector needs to know a lot of information that perhaps he'll know or perhaps its in the manual. Most likely, it isn't addressed at all, so it will be up to his comfort level to decide what to approve or disapprove.

    If you changed to THWN, you could probably use the same clamp that is holding the SJ cables. Individual wires are much more flexible than a jacketed cable or cord. You don't really need much of a cable clamp when using individual #14 THWN wires. You could cable tie them together if necessary.
    Mark
    Kent, WA

  10. #40

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    Slooo,
    I really can't tell where the gray wire ends, I was hoping the schematic would help. I went to the store to pick up the refrigerant seal, but couldn't find it. They did have a few different copper pipe sealants, I picked one up that has a pressure rating of 12,000psi for liquids and 2,600 psi for gases. It's from Hercles and called Block. The mini-split company told me over the phone that the quick couplings would be fine so I probably won't use it. If there's a problem I'll probably get the AC company to supply me with some. Which reminds me, what about a "tap" so they can charge the line more thoroughly like you were talking about? I looked for that but could not find it.


    Mark,
    I don't know what to do about the gray wire. I guess I could run it by itself in the conduit on the right side in that picture. Before you asked if it had a voltage rating on the jacket of 300V or higher. It does; so that means it's ok???

    I did pick up 14 gauge THWN for EVERYTHING and it's thin enough that I could fit the 6 "interconnect" wires and the 3 power wires in one 3/4" piece of conduit. Actually, would that be acceptable? That would take care of the gray wire. I'm not even sure that the gray wire needs to be in conduit, their diagrams and instructions don't mention it. I also picked up some zip ties with a screw hole - that should work fine as a cable clamp in the wall, right?

    Here's the layout. On one wall the air handler is mounted. The conduit leaves the handler and goes down the outside of the wall and there's a wall that is about 4' away. It enters the wall and exits 6" lower to the outside. The compressor is 2' away and there's 7' of conduit (now there's 2) outside going to the connections area of the compressor. For the 5" of space when the wire is in the walls there is no conduit, just conduit clamps to protect the wires from the metal of the service entrance (on the inside) and the non-service-panel (on the outside).

    I'll go ahead and move the 10-2 to the left side of the NSP.

    Thanks again for the help,
    Dan

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