Voltage drop

[defadog]

Before I cut this out..would you assume it is the problem? Now way of testing supply side without removing joint!

 

[conny]

Any idea where that side cable goes?
Is it possible someone has tapped into your supply?

 

[defadog]

No, side cable is what supplies my shed. Main cable feeds old pump house. So 125v measured on both pump house and shed, 240v on garage where feed comes from. I am guessing corroded contacts inside the resin...but cannot prove without breaking cable out.

 

[bernardgreen]

Long shot but could that tap be in series with the supply to the pump house

The capacitance in the cables would create a voltage divider producing less than 240 volts on each of cables

 

[defadog]

That is entirely possible - But it all worked fine a couple of months ago. There is no load on the old pumphouse..the pumps were removed, and the cable terminates at the old isolator. And what can explain a drop from 237 to 125? I can only assume a massive impedance on the supply? Although if they were in series...and i remove the connection on the spur...I would break the supply to the pumphouse...which might then explain it ?

 

[defadog]

Either way, It is time to remove and do properly I think - I dont need the spur the the pumphouse, it is not a useable space.

 

[defadog]

In fact the more I think about it, the more it makes sense. Thanks Bernard..good bit of lateral thinking!

 

[defadog]

Definately a bodge job. And resin cracked. Bad news , having removed joint the problem remains..110v L to N, 198v L to E on open wires. So..supply at house 240, supply at garage 240, supply at end of long cable connected to garage..110v.
I suspect the T to the garage will be the same bodge.

This is a 6mm dia conductor, so no way the cable itself has broken or been damage. So I guess I find the garage connection (the garage will be on the spur is my guess)..unless anyone has any other ideas?

 

[DetlefSchmitz]

Since you never responded to my post suggesting you were using a high input impedance meter to do the measurements, I have no idea whether that is the problem.

 

[defadog]

Hi Detlef..I am using a bog standard meter, but dont really understand the problem. The same meter measured 237 in the shed when I was checking to see if I could provide sufficient power for my wood splitte a couple of years ago. It has worked fine for the 9 years we have lived here. Nothing has changed, so something has failed. Given that there is only one place we can have a problem that I can see unless you can suggest an alternative?

 

[DetlefSchmitz]

OK - I have probably misunderstood the issue. I rather gathered you were making measurements on a circuit which was switched off. If this is not the case then ignore me.

 

[RF Lighting]

What ever happens, that joint can not be left in service! I’d think there’s a very good chance that this it where your fault is. If you can manage to dissect it it would be interesting to see what state the insides are in.

 

[defadog]

Sadly not. Removed the entire joint...will disect later. But with open cable voltage is as stated. 240v main board, 240v garage, but on the open cable some 40m away 110v L-N, 198v L-E. That this removed joint was a bodge is not in doubt...the plastic case had been broken apart, and the original o rings that held the earth strap has been replaced (but left on the outer sheath).
The worry now is...how many more joints, how many more bodges?
Plan now...disconnect completely from main board, short circuit open wires near shed, and test impedance at the garage.

 

[Harry Bloomfield]

Hmmm! Obviously without intending any disrespect to you, that sounds ridiculous - something crazy is going on

Has the test meter been checked out? I was once caught out by a meter into which moisture had managed to get, it was producing some really silly measurements.

 

[defadog]

Harry, checked against another meter from a friend.
New results..and no surpises. Disconnected cable from main board and connected cores together. In theory, one long loop with a single spur and this is 16 or 20mm cable, hard to measure. Resistance across LN in garage - 0. Resistance across LN at open cable near shed..10K!
Interstingly, the neutral when stripped back by the shed has got copper oxide between the strands. As far as I know that only means one thing...moisture.

My theory is that garage junction is fine based on no resistance and zero voltage drop...and there must be another junction between that and shed. How do I find it...or do I just lay a new 40m cable!