Din Rail terminal blocks

[Aragorn84]

Planning to use these (or similar) in a Din rail enclosure to extend some cables:

http://www.entrelecsales.com/terminalblocks.htm


Does anyone have any thoughts on whether the "spring" type are better/worse than the screw down type?

My initial feeling was towards the spring type, but i'm not really sure why, and talking to a guy at work he said all the ones they use in our building are the screw down type and that he prefers them. He also pointed out that you need a screwdriver to operate the spring type anyway, so theres little/no efficency gained by using the spring type, and they can be more fiddly to use.

 

[ericmark]

The spring type are designed to be maintenance free. All screw connections can work lose with vibrations but the building will determine how often they need checking. A steel framed concrete batching plant will likely need screws checking every couple of months but a house more like every 10 years.

They do save money in maintenance costs but not testing for tightness also means other tests are also omitted so not sure it reduced maintenance is good.

Where flexible cables are used one has to use pin crimps however that's not a bad thing as it keeps the cable numbers on the cable.

For small control cables I do like the maintenance free as years of checking if screws are tight will in the end compress the cable so much it breaks anyway but for larger cables I like the screw type. Using Alan keyed screws with T bar drivers puts far more pressure on the wire than any spring. I have never used spring type on 16 mm² cable but on 1 mm² they are very good.

Problem is when you open the board see maintenance free and close it again without realising not all are maintenance free.

 

[bernardgreen]

My experience with the earlier spring ones were that they worked

There was concern that a current overload could cause localised heating and this would weaken the spring leading to a permanent reduction in contact pressure.