70volt AC ??

[user 28643]

Dear gentlemen

I live on an old farm in Mallorca. Battling with (part) ancient electrical wiring which i am slowly repairing and replacing. Most of it is pretty straight forward. 

There is however, one outside lamppost that is refusing to give light. I measured the voltage of the leads going in to it, and the display on my multimeter reads about 70 volts. It should of course go towards 220 volt

my question:  can this be caused by a corroded connection further down the line? In a switchbox for example?

Are there any other possible causes?

any suggestions will be most appreciated

alex

 

[Andy™]

probably dodgy connection somewhere or a faulty cable. could be many things

 

[Evans Electric]

Is the cable buried ?    If so , as Andy says , it could have been damaged ,    is there a switch for it  ? If so is there 220V in the switch .

How does the lampost turn on & off?     Time switch  ...photo-cell? 

 

[user 28643]

Thx for the responses.

the lamppost is one of 6. All cables are buried. Probably more than 30 years ago. The switch-on, is done directly on the circuitbreaker-box in the house. The other 5 work just fine.

guess i have some more investigation to do on where the 'connects' are made. It is all done like a daisy chain. And yes, this one is the last one in the chain. 

 

[poni]

should have read the complete post derr

 

[Evans Electric]

Well logic says there is a fault between the last post that works and the faulty one .    Do the posts have removable covers ?  Electrics would be in there , need to investigate the  connections in both posts  and the cable itself .   Do you have any other test instruments ...you obviously have a voltmeter. ?  

Well they must have covers for you to read the 70V   ( Its been a long day)      An insulation test on the cable would be good if you have a meter .

Not much else we can advise without being there to be honest .

 

[user 28643]

Thanks Evans for your interest

your reply does bring a smile to my face.

i guess you have never looked at Spanish wiring before. Hahahah

most of the cables either dive deep into the ground and/or are cemented in. So, it is a real challenge to figure out what Pablo and Pepe have done many decades ago.

my plan of attack (for tomorrow) is to replace the last couple wire-connectors in a box outside. It is quite a mess. I cant see logic of what they did. All i can do is freshen the stripped wires and reconnect them. Hoping for more conduction.

as the muslims say, Inshah Allah or god willling

 

[user 28643]

The lamppost won the battle.

I have conquered inhabitants of a plastic distribution box outside (a lizard and 2 naked snails) 

I have replaced about 12 wire-connections with freshly stripped wires.

and unfortunately it made no difference. 

I guess that all the cables for these lampposts are separate from this box. And are nicely integrated into the concrete wall the lamps are mounted on. Very handy indeed.  (bloody idiots !!! ) 

 

[Geoff1946]

If your meter is a high impedance type, that 70volts could be just capacitive/inductive pickup on a wire which is physically close to others but completely unconnected. (This is compatible with the damaged cable theory suggested already). All I'm really saying is don't trust readings from a multimeter in this sort of fault-finding.

 

[phil d]

There are 2 options here, open the box and disconnect those cables, now you say there are 6 lights and 12 cables in the box? So that would lead you to think something's missing for a start, if we say 6 lights and 12 wires then ignoring the earths (they usually do) that's 2 wires per lamp, 1 live, 1 neutral, straight away there aren't enough wires, should be 14, 2 coming in and 12 going out. However if there were 14 and they were connected in 2 lots of 7 then there would be enough cables, in which case I'd split them all, find the live and neutral feeds then connect the others 1 pair at a time, the pair that doesn't light is then obviously the offending light. If as you suspect they are looped fitting to fitting then you'll have to drop number 5 and check the loop in there, alternatively disconnect the wires at the offending lamp and hook them up to an extension lead, if the lamp lights it proves it's the feed, if not it could be in the fitting

 

[user 28643]

Great to see you are not as easily defeated as I am

since i have no (zero) education in electronics, i am purely working by logical deduction and trial and error.

i did already connected the obnoxious nr-6 to the mains using a powerlead into a 220 volt socket.  The nr-6 worked with this. So the internal wiring of the lamppost and the bulb are fine. It has to be the feed going into it.

i also dismounted the nr-5. Hoping to find evidence of how it gets its power and if there was a feed going towards nr-6. Alas, no such luck.  Just a single wire (2 cables) going into it from out of the concrete. 

Very little diagnostics possible there

the plastic box outside is a  bowl of spaghetti. It also drives the power to the other sets of lamps on the driveway as well as the electronic gate. 

Come to think of it, i am not even 100% sure that the power for my 6 lampposts comes from that box. I will test that tomorrow. 

Thanks for your advise!

 

[user 28643]

Halleluja !!!!!

I fixed it. The offending lamppost is now working in concert with the others. Basically, I dug into the cement post to find very bad wiring connections. just twisted together without any insulation. Needless to say, they were so badly corroded that it was falling apart at the touch. 

See below some pictures of what I had to deal with

 

[Lurch]

Well done. Nice to see an issue updated with a resolution.

 

[Andy™]

and the finished result doesnt look too bad either

 

[Doc Hudson]

Thanks for the update, always nice to hear how these sort of problems get resolved.

Doc H.