Grease revisited

Discussion in 'Landscape Lighting' started by steveparrott, Oct 18, 2010.

  1. steveparrott

    steveparrott Sponsor
    Posts: 1,182

    I just had a call from a contractor reporting an orange film forming on the inside of MR-16 bullet lenses with 50W lamps. I'm pretty sure the film was caused by out-gassing from the grease the contractor applied to the lamp pins.

    This led me to do a little research on greases used for this purpose (incl. reading the many posts on this topic here).

    One of the things that surprised me was the misuse of the term 'dielectric', and the fact that some contractors use dielectric (non-conductive) grease and others use conductive grease.

    Most expert opinion seems to discourage the use of non-conductive (dielectric) grease on socket contacts because it can interfere with the socket/pin connection - in fact, the connection can only be made because pushing the pin in the socket scrapes away the grease. Some claim that the resultant connection has more resistance than when there is no grease, and that this resistance can result in voltage drop and excess heat in the socket.

    It makes more sense to use conducting grease (if any) because this makes for a good contact and protects against corrosion. In fact, one popular grease used by our forum readers is the Sanchem No-Ox-ID "A Special" - a conductive grease (although many posts referred to it incorrectly as a dielectric grease).

    Getting back to my intial complaint (orange film residue) - the contractor didn't know what type of grease was used, but regardless of it being conductive or non-conductive, I'm guessing the 50W lamp pushed the heat past its specs.

    As you may know, CAST doesn't grease its sockets and doesn't recommend its use. We believe that our solid nickel pins mated to the solid nickel socket contacts are sufficient.

    Comments on the grease issue welcome.
     
  2. irrig8r

    irrig8r LawnSite Platinum Member
    Posts: 4,535

    Interesting observations Steve.

    So, I did a quick search on "conductive synthetic grease" and got this list of manufacturers:

    http://www.thomasnet.com/products/conductive-grease-35691401-1.html


    Would a grease rated to 200 deg F be appropriate in lighting fixtures? Is 500 deg F overkill?

    I'm assuming synthetic is better than petroleum-based, but that's just because I'm thinking of volatile compounds released by heating... maybe even depositing on the inside of lenses.

    Keeping moisture away from the connection between pins and socket seems an obvious goal to me... grease is kind of a backup solution when moisture isn't completely excluded by the fixture design and construction....
     
  3. steveparrott

    steveparrott Sponsor
    Posts: 1,182

    Our sockets are rated for 250 degrees C (482 degrees F). You could shoot for that.
     
  4. Prolightscaper

    Prolightscaper LawnSite Member
    Posts: 65

    an orange film forming on the inside of MR-16 bullet lenses with 50W lamps

    some of the cheap straight from china MR-16 bulbs out there emit all sorts of funky stuff inside a small fixture like that.

    I would never put a 50 watt in a small fixture body. It gets as hot as a branding iron and is not safe to the touch. What happens when a small child comes along?

    Is that fixture rated for a 50 watt lamp. If so I still would never put a 50 watter in there. It's just pure common sense.
     
  5. steveparrott

    steveparrott Sponsor
    Posts: 1,182

    The lamp was a quality brand, so I don't think the lamp was the problem. The fixture is UL rated for 50W, but it does get very hot. We put heat shields on all our bullet sockets specifically to direct heat away from the socket for those who use 50W lamps.
     
  6. Prolightscaper

    Prolightscaper LawnSite Member
    Posts: 65

    We put heat shields on all our bullet sockets specifically to direct heat away from the socket for those who use 50W lamps.

    How does a heat shield installed inside a 3" X 2" closed oven direct heat away from a socket? :confused:
     
  7. Alan B

    Alan B Sponsor
    Posts: 406

    The same way a heat shield/reflector deflects heat away from anything else. It doesn't mean the socket is cool, but its reflects much of the heat. The body gets hot, but not near as hot as the lamp for example.
     
  8. INTEGRA Bespoke Lighting

    INTEGRA Bespoke Lighting LawnSite Platinum Member
    Posts: 4,102

    Hey "Prolightscaper", you seem to be quite the contrarian here on the forum. All this challenging, posturing and questioning and yet we don't know who you are. :confused:

    So how about doing all of us here in the Lawnsite Family a small favour and tell us your name, business name, background and that sort of thing. Having some knowledge of, or reference to one's work and experience can go a long way to better understanding.

    Thanks.
     
  9. Alan B

    Alan B Sponsor
    Posts: 406

    Steve,

    Guilty as charged. Thank you for the correction. Volt uses "Conductive Grease" on all our sockets and choose Sanchem No-Ox-Id and are very happy with it. We have had zero socket failures and zeros issues with it.

    It is not just a conductive grease but tolerates high heat and does less prone to liquefying and evaporating (wax based instead of petroleum based). We tested many greases and found it performed the best (sometimes I give out too much info!).

    With my boating/marine experience I would strongly choose to have my electric connections greased, and Volt believes contractors should grease their fittings, including sockets, even when using good metals like nickel on nickel connections. We have never had one socket failure, however 2 years is not a long enough track record to draw much from.

    Good luck to you, however for now Volt will stick with and believe in pregreasing our sockets and screws with grease.

    Cheers!

    Sincerely,

    Alan
     
  10. David Gretzmier

    David Gretzmier LawnSite Gold Member
    Posts: 3,645

    grease is also not only for the springs and contacts within a socket, it helps prevent galvanic corrosion between dissimilar metals with electrical current involved of the pins and the sockets. many of you may have seen dry white powder on the pins of bulbs you have removed that have been in place far past thier useful life. This, over time, will rot stainless pins into the socket. I seem to see it more with the ultra 10000 hour bulbs that were pretty popular several years back, or bulbs that I replace that are 3 years old plus.

    This is especially important with the newer LED retrofit bulbs. without yearly bulb changes, those pins need to be periodically cleaned and sockets regreased.

    we currently use a 3M clear synthetic grease that lists electric sockets on the label, purchased locally from Grainger. I am not sure of the 3m number. I believe it was reccomended a few years back by someone on this forum.
     

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