Model Railway Forum

Your comments are interesting, Brian. It may be as well to be sure from the outset that we are talking about the same thing. I'm looking at a Peco Streamline code 100 Insulfrog double slip crossing, cat. SL-99. The date on the instructions card is 02.16. Assuming this is what you also refer to, I'm afraid I must continue to disagree with you. If not, I stand corrected.

I tested said double slip in isolation. I attached crocodile clips to the middle of the two outer rails as in your diagram and turned on the power. The voltmeter registered 13.28V DC at this location. I applied the meter's probes to each pair of outlet rails and got the same reading, regardless of how the blades were set. I attached the crocodile clips to the rail ends of one outlet track and again got 13.28V DC. I also got 13.28V DC at the three other exits and in the middle of the crossing, in fact wherever I set the probes and again regardless of the position of the point blades.

Looking at the underside of the crossing, it is possible to see connections between all rail sections on each side. The stock rails are connected to the point blades, the wing rails and the rail ends beyond the frogs. Pic attached.

The function of an isolating point depends on moving the point blade away from the stock rail. This only works when there is no other connection between the stock rail and the wing rail. On the Peco double slip, there is this connection. Or has the crossing you have been modified in any way?

Cheers,
Artur

I must also disagree, even the older '70s code 100 slip is wired as non isolating.

It seems you're correct! Though I dont have one to check. The Peco Insulated frog double slip point is not self isolating. My error!
The last one I installed was on my clubs layout in 2013 and was wired as I showed. But the self isolating was never checked as its turnout directions lead from an Electrofrog standard point and the parallel lines are on two separate DC controllers, so IRJs were fitted anyway on the end of the Electrofrog points and others used for power separation.
You learn something new everyday. The drawings are correct for mechanical working similarities, but the Insulated frog DS does need IRJs on the frog Vee rails if the tracks beyond it are required to be isolated.

I bought a couple recently to replace some points but decided it was too much trouble having to add switches because they would be fed by two different controllers. Sold them, at a bargain price, to one of our members.

I take it the picture is of your layout, Brian. Very nice. I particularly like the middle road between the platforms. Very Great Northern. When I was a kid we lived close to the ECML and at Harringay, Hornsey or Wood Green you could stand back a bit to watch Pacifics and V2s race through. Sorry to be a bit off topic here.

Cheers,
Artur

No not mine its my clubs. The club was formed in 2012 by myself and five others (now we have over 40 members) and the OO Code 100 layout started to be constructed that same year. The following year is when track was laid onto the baseboards and wired. You can see progress of 'Bysing Wood Junction' as its called on the club web site... https://www.favershammrc.org.uk/Index.html

Morning all,

So going back to my original post, can anyone advise how to get round this issue, in simplified Lehmanns terms of course!

Thanks

David

You need to fit one IRJs to the exit rail for each direction that you want to become isolated. Then run a new feed to the rail after the IRJs and add a simple On/Off switch into that feed wire to allow total isolation to occur.