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Connecting and insulating wires in high temp environments

Discussion in 'General Electronics Discussion' started by primuspaul, Feb 18, 2018.

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  1. primuspaul

    primuspaul

    91
    1
    Feb 7, 2018
    How do I connect and insulate wires in high temp environments? I'm talking about 600-700 F heat, so soldering and heat shrink are not possible.

    I have this crimper:

    https://www.amazon.com/gp/product/B0045CUMLQ/

    jaws.png

    Often when I try to crimp open barrel connectors, I either get loose connections that come apart or the crimp is so tight that half of the wire strands get cut! Can someone give me some advice? Are there alternatives to crimping in high heat environments, like welding the wires together somehow? I was also considering brazing wires together with low melting point brazing rods, since I have a soldering iron that goes as high as 899F. I also have this butane torch:
    https://www.amazon.com/gp/product/B000WOHSHM
    Will that get hot enough?

    And what's the best way of isolating the wires from each other and nearby metal chassis?
     
    Last edited: Feb 18, 2018
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,497
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    Jan 21, 2010
    Use the correct crimping tool and connectors for the wire you're using.

    For really high temperature stuff, bare solid wire covered with woven fibreglass and kept physically separate from other wiring and the chassis.

    And yeah, using something with a higher melting point that the ambient environment is good :)
     
    hevans1944 likes this.
  3. primuspaul

    primuspaul

    91
    1
    Feb 7, 2018
    That's what I'm asking. What is the correct crimping tool? For example, what jaw do I use with this:
    https://www.ebay.com/itm/100pc-Open...ket-BL2-195A-0-TAB-4mm-RoHS-CALY/141181794951

    and how do I tell the gauge if the wire and pick the appropriate jaw section?
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,497
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    Jan 21, 2010
    There documentation for the connector should give you all the information you need. If these are cheap connectors with no documentation, then you're a bit on your own.

    I tend to use crimp connectors which have a hollow cylinder to place the wires in before crimping. Individual strands can't escape, and because you don't crimp right up to the end the strands are protected.

    If you're having trouble with these connectors, you may be able to try a bootlace ferrule to protect the wire. These are typically crimped using a tool that crimps them in a square or hexagonal pattern.

    Having the correct crimping tool is important. The cheap ones you get from auto stores are a recipe for poor crimping, especially if combined with connectors that don't match them.
     
  5. primuspaul

    primuspaul

    91
    1
    Feb 7, 2018
    I didn't get mine from an auto store, I got it from Amazon and it's a pretty good brand. I never thought about using cord end terminals. I do have a tool that can crimp them, however. So you crimp the wire in a cord end terminal first, THEN insert and crimp the crimped cord end into the final terminal?

    So far I've only been able to find the wraps they use for tail pipes as far as insulation is concerned. Anyone else come across any high temp insulation that resists 700-800 degrees F?
     
    Last edited: Feb 19, 2018
  6. kellys_eye

    kellys_eye

    4,275
    1,147
    Jun 25, 2010
    Many ratchet crimp tools like the one shown have an adjuster to set the maximum crimping pressure and if it's set 'too tight' will cause core 'snipping'. Check the tool user instructions.

    Silicon sleeving is good for high temperature wiring or, as already suggested, woven fibre glass. If you check out the major electronics suppliers you should be able t see what they have a stock delivery items for this purpose and get the datasheet for them that reveals precisely the temperature range you can use them in.

    For the range you want (around 400C) you should look for acrylic saturated fibreglass sleeving
     
    Last edited: Feb 19, 2018
  7. Bluejets

    Bluejets

    4,993
    1,048
    Oct 5, 2014
    Could also look at fibreglass cable as used in cookers etc....from memory about 1.5 sq mm (15a) and ceramic terminal blocks
     
  8. Tha fios agaibh

    Tha fios agaibh

    2,168
    727
    Aug 11, 2014
    It's worth mentioning that you can often get away with much lower temp ratings by simply re-routing the wire or using shielding. This can be done with a metal shield, silica fabric, fiberglass, conduit...etc.

    When I splice in high temp areas such as furnaces, I usually just use standard uninsulated crimping lugs such as T&B, and then cover them with fiberglass sleaving that can be purchased by the roll. Then I secure it from sliding with stainless steel cable ties or aircraft cable.
     
  9. primuspaul

    primuspaul

    91
    1
    Feb 7, 2018
    Can you link to an online source that sells that sleeving?
     
  10. primuspaul

    primuspaul

    91
    1
    Feb 7, 2018
  11. FuZZ1L0G1C

    FuZZ1L0G1C

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    Mar 25, 2014
    If you have an electrical component store near you, the type that stock heating elements, thermostats, etc they should sell fiberglass sleeving per meter, used for insulating wires.
    As this sleeve is soft and flexible, simply slide it over the un-crimped conductor, cutting it slightly longer than wire end.
    Slide it back before crimping, then once connector / lug is crimped, the sleeve will naturally butt up against the connector as it re-expands.
     
  12. primuspaul

    primuspaul

    91
    1
    Feb 7, 2018
    What if I'm crimping a wire to a wire and need the sleeve to slide completely over, and then some, over the crimped wire section? There's nothing for it to "butt up" against so there's a good chance the sleeve can slide again after installation, exposing the bare metal crimp. I was wondering if there was something I can tie on both sides of the crimp to tighten each side of the sleeve to the insulated wire underneath.
     
  13. FuZZ1L0G1C

    FuZZ1L0G1C

    368
    118
    Mar 25, 2014
    Electrical Heat-Resistant tape, sold at many hardware stores.
    Being adhesive-backed, and the woven glass fiber incredibly strong, you can either tightly wrap the ends of a glass fiber sleeve which sits over the ferrule, or tape-wrap the entire connection.
    The tape is white, with a woven cloth texture, and is distributed here as '3M' electrical tape.
     
  14. primuspaul

    primuspaul

    91
    1
    Feb 7, 2018
    3M electric tape can resist up to 800F temperatures? I thought pretty much all of these adhesives and PVC/Vinyl-based tapes melted even before solder. Can you provide a link to this heat resistant tape?
     
  15. Tha fios agaibh

    Tha fios agaibh

    2,168
    727
    Aug 11, 2014
    Screenshot_2018-02-20-04-59-58-1.png
    like I said I use stainless steel ties, or aircraft cable (over it)to secure it from sliding off the splice. I wouldn't use tape (over it) because it usually starts to unravel.
    But, using tape over the crimp but under the sleeve is ideal to make a nice smooth (no big lump) base for the sleeve.
     
  16. primuspaul

    primuspaul

    91
    1
    Feb 7, 2018
    I tried those ties, but they don't form a very good friction connection with the wire. Seems the "lock" on those ties makes them less than ideal for clamping tightly onto small/thin objects like a wire. Seems they work better on things at least 0.5-1 inch in diameter.
     
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