testing problem

[grumpy17]

Hi to all,
I have a question im hoping someone can answer for me.I have just bought my first multi test meter a seaward 1557 which does eveything it should.But when i tested the rcd times it refused to do a test at 1x and came up with >50v on the meter and stopped the sequence.My system is a tncs and the rcd is a normal 80a 30ma one.Does this mean I have a fault with the rcd or the meter or something more sinister.Any advise would be appreciated.

 

[Carter]

The tester is detecting a touch voltage exceeding 50v on the cpc. It rightly sees this as an unsafe condition and locks out any further application of the test. You have an earthing problem here. Have you done a Ze and continuity of cpc's and any bonding prior to doing the 'live' test? at what point in the cct are you testing?

 

[grumpy17]

Hi I havent actually done anything to the house I was just testing the machine on an rcd I assumed there was a problem but its a new house and thought it must be the machine.I shall go test the whole system and see what comes up and get back to you.Thanks for now.

 

[Carter]

Tell you what though, it does show up the potentialy dangerous pitfalls of partial testing. The earlier stages are all vital parts of the process of ensuring that the installation is safe to energise either from the mains or via a test instrument. Hope you find it chap

 

[ian.settle1]

Hi I havent actually done anything to the house I was just testing the machine on an rcd I assumed there was a problem but its a new house and thought it must be the machine.I shall go test the whole system and see what comes up and get back to you.Thanks for now.

Have you tried it at a different location but not the same house to see if you are getting the same problem?
If you are it may be a duff meter you've got.

 

[grumpy17]

Hi again, I have tested the whole system and eveything was ok Zs and psc and pfc all checked out fine.But as soon as I took all the wires out of the c/u I spotted an extra wire in the sockets cb which led to the hot water cylinder.When I rcd tested the sockets and oven all was fine with each of them.As soon as I connected the water cylinder to either circuit and repeated the test the tester shut down again.Ive now given the water heater its own cb which seems to have cured the problem. On the suggestion that I try it out to see if it was a dodgy tester.I did that on my parents house and found that the so called qualified electrician who put in a new c/u some years ago has wired the incoming tails straight into the rcd so shutting off the main isolation switch only turned off the lights.Goog job I followed procedure to check if it was dead,my dad may not have been so lucky if he'd fancied a bit of extra socket diy.
cheers for now.

 

[Carter]

Some investigation needed on that cylinder cct. they are a bit 'earthy' by nature but should not be producing touch voltages sufficient to shut down the test. How old's the wiring? (am assuming that the actual element load/neons in old hidden but still connected FCUs/any oddly wired stats? are out of cct.)

At least it's proved your Seaward is okay.

 

[grumpy17]

The house is only 7 years old but have done some investigation into the history and the original water cylinder was chucked out when it tried to come through the ceiling in the hall way after spinging a leak.Everything was re-sited in the understairs cupboard but on looking around the back of it I cant see any bonding on the pipes at all.As it isnt a special location I guess there wasnt a requirement to do so but could this explain the high reading.I can see an external time clock has been added to the system but all seems ok with that.

 

[jeremy]

I did a quick test in a friends pub kitchen as the chefs were shocked every time the touched the deep fryer(thats not a profound monk) ----ers who had had the pub before had done a bit of DIY and not bothered reconnecting the CPCs of the fryer , 2 lighting circuits and the extractor circuit( nothing to do with John Deere) 107Volts of beautiful induced voltage. It's enough to wake you up on a saturday am, I promise you that!!