Door Contact Help

[sbex55]

I could use some help on door contacts.  I have two double french doors and a single door to arm.  I've attached a picture of the top of one of the doors.

If I'm going to get a recessed contact in the top of the door the only potential location I have is the small metal plate 4-5 inches in from the edge.  The door diagrams show it's hollow under the plate but I can't get any information on the plate itself.  Should I continue to pursue this approach or is it a bad idea?

If I can't use the top of the door I guess my options are either plunger or surface contact.  I've read the plunger type is susceptible to sticking.  Also I really don't have a wire path to the side of the door.  

If a surface makes the most sense, I only need a small hole to fit the wire up through the header but I still need some room to add the EOLR.  Will a 3/8" hole be enough room?  Will a Honeywell surface contact cover the hole through the door frame?

Thanks again for your help!
 
ps - sorry for the sideways pic.  8)

 

[RAL]

Your question is really about where to put the magnet, right, since the contact itself will be embedded in the frame above the door.
 
This seems like a good place to use a rare earth magnet.  You could simply epoxy it to the top of the door without drilling into anything. The main question is whether that metal plate is made of steel or not.  But that's easy enough to tell just by testing it with a magnet to see if it is attracted to the plate.  
 
If the metal plate turns out to be steel, I wonder if you couldn't fit a rare earth magnet somewhere else along the top of the door since they are so thin.  Is there something that would prevent you from using the spot where the wood is exposed? 
 
You should be able to fit the wire and EOLR into a 3/8" hole.

 

[sbex55]

Your question is really about where to put the magnet, right, since the contact itself will be embedded in the frame above the door.
 
This seems like a good place to use a rare earth magnet.  You could simply epoxy it to the top of the door without drilling into anything. The main question is whether that metal plate is made of steel or not.  But that's easy enough to tell just by testing it with a magnet to see if it is attracted to the plate.  
 
If the metal plate turns out to be steel, I wonder if you couldn't fit a rare earth magnet somewhere else along the top of the door since they are so thin.  Is there something that would prevent you from using the spot where the wood is exposed? 
 
You should be able to fit the wire and EOLR into a 3/8" hole.

 
Thanks for the suggestion.   I was not aware I could swap the magnet portion of a recessed contact with another type/shape magnet.  What sizes and shapes can I get and where do I get them?  Would it be possible to find one to fit into the small metal channel shown in the picture?
 
I can't use the wood portion of the door because there is a metal plate in the frame above it.
 
Thanks for the help!

 

[RAL]

Most of the alarm suppliers, including Automated Outlet, carry rare earth magnets, If you google MM400 or MM600, you'll find a number of sources,
The MM400 is a 3/8" diameter magnet, while the MM600 is 5/8".   They usually sell for $1 to $2 each.
 
Despite their small size, they allow for pretty good gap distances.
 

 

 

[42etus]

These guys have what you'll need
 
http://www.kjmagnetics.com/categories.asp?gclid=CIOV6urvoboCFUXhQgod9kQAng

 

[RAL]

If you choose a magnet that is something other than a MM400 or MM600, which are meant for use with recessed contacts, you need to be careful that the magnet has its poles oriented correctly for the way you plan to mount it, otherwise it may not work properly with the contact.
 
Different disc type magnets which may look identical to the MM400/600 may have the north pole facing out, or the south pole facing out, or may have the poles around the edges of the disc.
 
How you plan to mount the magnet on the door matters.  The MM400 and 600 are meant to be mounted flat on the surface opposite the contact in the frame.

 

[JimS]

I think you could put a rare earth magnet on the plate regardless of if it is steel of not.  You could test it easily enough without drilling any holes or cutting anything.  Get the magnet you plan to use and place it on the metal (use tape if not steel or if steel it will stick by itself).  Then hold the switch near the magnet in the position and at the gap it will have.  Might help to have some cardboard or a board the thickness of the final gap.  Then slide the magnet off to the side in different directions slightly so see how much it moves before the contact opens.  Then lift it slightly until the contacts open.   If you can move it around a bit before it opens it should work fine.  Use a multimeter to check if it is open or closed.
 
If it looks good just glue the magnet on the plate.  It looks like there is some room for the magnet where the plate is.
 
If the plate location doesn't work you can test other locations in the same way. 
 
If you have a rod magnet and you have enough room you may be able to lay the rod flat on the top of the door with the switch at one end of the rod (not the middle!).  Again, you could easily test that.

 

[Del91574]

Hate to say it to you guys, but the suggestions to put a magnet in/on/under/around the steel plate is a bad idea....amateur move that will lead to false alarms.
 
There's plenty of room to install a regular contact in the top of the door and use a 3/8" or 1/4" magnet in the wood section of the door between the locking hardware. There's enough meat there to drive a truck through.
 
Remember, just because the contact is 3/4" the magnet can be any size, or vice versa, as long as it lines up.
 
There's also a straight wire path to the butt side of the door for a plunger or roller contact if you're not feeling brave.

 

[sbex55]

Hate to say it to you guys, but the suggestions to put a magnet in/on/under/around the steel plate is a bad idea....amateur move that will lead to false alarms.
 
There's plenty of room to install a regular contact in the top of the door and use a 3/8" or 1/4" magnet in the wood section of the door between the locking hardware. There's enough meat there to drive a truck through.
 
Remember, just because the contact is 3/4" the magnet can be any size, or vice versa, as long as it lines up.
 
There's also a straight wire path to the butt side of the door for a plunger or roller contact if you're not feeling brave.

 
Thanks.  I'd rather put the magnet in the wood section of the door.  The wood section is 7/8" square (top dimensions) and is recessed 1/2" from the top of the door.  Two questions:

1 - I don't think I can use the honeywell contact/magnet made for a steel door since the magnet has a 3/4" diameter bushing with a 1" diameter top.   Do you think the non-steel 3/8" door magnet would be reliable in this location?

2 - Can I install the magnet with 1/2" extruding from the wood to make the gap smaller?  The drawing for the magnet housing shows 1.3" in length.  I'm not sure how I would secure the magnet since it wouldn't be pressed fully into the hole.

Thanks!

 

[Del91574]

1. Yes. I'd probably use the 3/4 contact 3/8" magnet set that Honeywell makes or a 3/8 X 3/8" set if you're really worried.
 
2. If you get a standard 3/8" magnet, you can cut the magnet free from the plastic. Usually with most, it'll get you a 1/4 X 1" bare magnet. Drill 1/4" hole and then press fit until it clears the door jamb.