Monday, 17 February 2014

Fitting Safezone Externally.

Greetings - Cronapress man here - As promised in my previous blog post I said I'd be dealing with the fitment of the Patented Safezone alarm strip externally. Once again instead of doing carefully composed 'mock-up' shots I shall be doing a live fit. The external fit has many similarities with the internal fitting so I'll only cover the differences in detail.           So here goes - Let's do it !                                    
Step 1 The aluminium extrusion should be cut to size, drilled with additional fixing holes if required (pre-drilled holes are provided which you may find useful) and securely attached to the wall or external construction. As I recommend in all cases inspection of the mounting area needs to be undertaken and fixings executed accordingly. Note -Allow for an additional 60mm each end for end caps.

Step 2
Fully insert end cap plate tangs into underside of extrusion, mark drilling holes, remove, drill and insert rawlplugs or similar..

Note the additional fixing screw near the edge in the base extrusion due to the uneven brickwork and also the channel that has been cut in the mortor. This will allow the wiring to sit behind the end cap plate and into a galvanised junction box.

Step 3
Fit the waterproof  L.E.D. into either the upper or lower channel in the aluminium extrusion. At this point it may be wise to test the L.E.D. strip with a temporary 12v battery/power pack as it will be time consuming to replace once the insert is installed and sealed.

Step 4
The insert can now be cut to length (if not supplied to size) The multi-purpose shears available from Cronapress are ideal. Information on them can be found on this blog.
NOTE - Cut the insert 10mm oversize each end.
This is very important as the oversize will be used to achieve the weatherproof seal. Sit the insert in the bottom channel and feed the top into place. Take care that the insert does not move when fitting as it will be difficult to re-position once fully home.

Step 5
Once the insert is fully seated into the upper and lower channels of the base extrusion then the wiring plugs are next. On this installation we will be using a Wired End plug and a 1k2 E.O.L. (End of Line) resistor plug.
These have been modified for external fitment and must be specified if needed at time of order. (The shoulder has been removed to allow them to push inside the insert strip.)

With the aid of a small screwdriver gently push the plug inside the insert so that the outer edge is level with the edge of the base extrusion. As mentioned above a 10mm overlap was allowed on the insert size at each end and this is the measurement we push the plug inside. This is of utmost importance so that the electrical contact point is positioned under the pressure point of the end cap cover.

Step 6
 Check for electrical continuity and if test ok then seal with silicone. Use a neutral sealer not a cheap Acetoxic type. We recommend Dow Corning 798. which also has Bacteriostatic qualities which would be of benefit if fitting in wet rooms or showers.

Re-check continuity.

Silicone Tech Talk-
Acetoxi cure.
This is the most commonly used, it is more rigid and the full cure is quick.  On the downside it generally has poor adhesion and leaves much to be desired for in how well it 'sticks' to PVC-U, most other plastics, glass, aluminium and Polycarbonate.  Shrinkage can be acceptable if it does not contain added solvent. 
Since the acetic acid is released during curing, it can attack the underlying substrate material. This can cause corrosion of certain metals and prevent the proper adhesion of the silicone. However, on other materials, the acid can etch the surface slightly and increase the adhesion. Aluminum is one such material. Copper and zinc, however, are corroded by the acid. Thus brass and galvanized steel should not be used with silicones which release acid. Dissimilar metals can form electrolytic couples and corrode severely underneath a covering of acetic acid releasing silicone.
Note the effect that the acid cure may have on the internal copper contact strip within the Safezone insert.
Neutral cure.
Much better adhesive properties for a greater number of materials including PVC-U, most other plastics, glass, aluminium, lead, stone and masonry, and Polycarbonate.  It cures with atmospheric moisture and skins over in about 30 minutes, and leaves a shinier finish.  On the downside it is more expensive and is slower to cure at one to five days depending on thickness, temperature and humidity conditions.
The benefit of using a good Low Modulus Neutral Cure Silicone can be summed up thus:
It offers high movement accommodation and excellent adhesion to almost all building and glazing materials, without any of the unwanted 'side effects' Acetoxi could possibly cause.

Step 7
Cap off the strip. 

Step 8
The galvanised 22mm conduit junction box has been drilled with a small hole to allow water drainage. Several times I have seen water collect in external trunking and ultimately lead to component failure. Failure will not occur in this instance due to the robust Cronapress sealing techniques but none the less water trapped in electrical conduits is definitely not a good thing and getting in the habit of reducing risk should be encouraged.

Step 9
Connection to the alarm cabling will be made with the same closed end connector crimps that were used in our internal fitting blog page. These will need additional weather protection as follows-
1)Cut the large opening part of the insulator from the crimp. 
2)Crimp the appropriate wires together 
3)Cover with Glue lined Heat shrink End Caps and apply hot air. Job done when tight and glue begins leaching from ends.

Step 10
Cover plate fitted and power on. (Just in time, it's raining again !)

Done ! Hopefully you have found the external 'live' fit informative and a fair representation of what can be achieved on site. If you need any more information on the fitment of our products then contact me at Cronapress.

Tools used.
Electric Hammer Drill, rawlplugs and screws.
Builders level.
Engineers hacksaw for cutting conduit.
Appropriate size screwdrivers.
Cronapress approved - Silverline General Purpose Shears.
Cronapress approved - Silverline Crimping Pliers.
Cronapress approved - Stanley Pin Torx Screwdriver.
Dow Corning 798 Silicone Sealer.
Cat 5 Alarm Cable.

Below - Special components used on this installation.
1) Waterproof LED
2) External fitment wiring plugs.
3) Modified Crimp Connectors - To allow heat shrink coverage.
4) Glue Lined Heat Shrink End Caps.

Cronapress man signing off until next time.
Remember - If it looks right it will be right ! If it doesn't - you guessed it - it won't !

and below is an poor example of external fitting....Now which do you think your customer would prefer?