Maintaining Temperature And Humidity In A Gun Cabinet - Sorted

[Apache]

Not sure if any of you remember this thread:

http://www.talk.electricianforum.co.uk/topic/21572-maintaining-temperature-and-humidity-in-a-gun-cabinet/

I had some good suggestions, but Canoeboy's panel heaters seemed the best bet.

I needed some kind of backing board and found something to do with racking in the CPC cat for a few quid so bought 3 of them.

5 rare earth magnets epoxied on the back.

Heater and thermostat glued down. Cable also glued to backing board. Cable tie at the bottom for strain relief.

Without going crazy I couldn't maintain 2 layers of insulation but they are locked in steel cabinets and I am the keyholder. I am not worried. All sockets on 30mA RCDs.

Cable runs to a 3 pin plug.

After a bit of fiddling with the stat settings I now have cabinets maintained around 20°C.

 

[steptoe]

shouldnt those metal plates be earthed? 

 

[Apache]

There is a self tapper through the crimped on ring. I just had to get some small enough so they were fitted the next day.

 

[kerching]

What size flex is it?..........careful now!

 

[steptoe]

you do know you are going to get ripped apart on this Apache.?

 

[Apache]

What size flex is it?..........careful now!

0.75mm. 3A fuse in the plugtops.

Steps - I can take it.

They are only 50w heaters.

 

[steptoe]

0.75mm. 3A fuse in the plugtops.

Steps - I can take it.

and the crimps are what size?  ...............

 

[Apache]

and the crimps are what size?  ...............

rated 30A

(I didn't have any yellow butt splice terminals on hand so I stripped the wire and doubled up the ends before tinning them with solder. That would give a thickness of over 1.5mm making a blue crimp suitable)

 

[ProDave]

rated 30A

(I didn't have any yellow butt splice terminals on hand so I stripped the wire and doubled up the ends before tinning them with solder. That would give a thickness of over 1.5mm making a blue crimp suitable)

You should really have used RED crimps for 0.75, certainly NOT yellow.

The important thing is to fill the terminal before crimping. So if your 0.75 does not fill a blue crimp (it won't) double it up so it's a snug fit before crimping it.

And you shouldn't really tin the ends with solder. The crimps are designed for crimping copper wire, not soldered wire. Tinning them will likely make them very brittle and more likely to snap.

 

[Apache]

Dave - after typing that last night I went for a look. I did not tin the ends in the crimps (although I gave them a good tug and they seemed secure). It was the ends that went into the stat and heater that got tinned. I kept getting stray strands and I don't like that.

 

[kerching]

Tinning ends can effect 'cold creep'...........

And not in a jimmy savile / Stuart hall/ Fred the weatherman ( got a related tale about that which I will post later) sort of way

...just saying

 

[Apache]

What is cold creep? Is that when the cold air gets back in?

 

[Sidewinder]

Imagine you have a carpeted dining room, nice thick carpet.

In the middle you put a very heavy dining table, think big old farmhouse type.

It has 4 thin legs though.

You leave it unmoved for say 5 years.

It regularly also has a lot of weight put on it.

After 5 years you lift the dining table up and take it out of the room.

You are left with 4 dents in the carpet, from the legs, yes?

That's seems the easiest way to describe cold creep.

The tinned ends are rigid and are compressed by the terminal screw, eventually they flow as the amalgam has plasticity, this would be exaggerated by typical heating and cooling cycles which could be seen in a heavily loaded electrical connection.

Your saving grace Apache is that the connections are not heavily loaded!

 

[kerching]

That must be the best ever description of cold creep I have ever read!

For that I will scoob you. Now that may not sound a big deal BUT it is the only scoob I have ever given!

 

[Sidewinder]

I GOT A SCOOB!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

WOW!

THANK YOU ALL!!!!

ALL SCOOBS gratefully accepted,

However, I refuse to beg for them like some I could mention...