Voltage test for completed cable

[isurunalaka]

Hi,

when low voltage cable manufacturing like 300v/500v, voltage test to be done for a 20m completed cable sample. To do this, 20m cable need to be immersed in water bath.

Can you please give me a reference for this complete test?

Thanks

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anyone know about this?

 

[isurunalaka]

anyone know about this?

 

[Surendhar M]

Do you want to test the cable whether it can able to withstand upto 300V or 500V. But then why you want to immerse in water? Not quite clear about your question....

 

[isurunalaka]

as per the BS6004 cable need to be immersed in water for predefined time. my question is to buy a appreciate water water bath for the test. i searched but could not find a predefined water bath for this specified test

 

[chuckey]

Any container that can accomadate your cable covered in water would do. Mark out your 20m, put in water, make sure the whole cable is immersed between the marks. In a dry place connect all the conductors together and using an insulation tester check the resistance between the conductors and another piece of bare wire hung in the water. I would think that this should exceed 200 M ohms, Dunking the probe into the water should give you less then 200 K.
Frank

 

[isurunalaka]

could you pls tell me where this testing equipment is available to buy? there are many water baths available but can not find the exact match for this voltage test.

 

[D.A.(Tony)Stewart]

An electric Hot water tank could be improvised to perform this Type test.

You should buy the standard , if you need it.

 

[TXBDan]

What application is this for?

I've designed harnesses for airborne and space flight payloads and have never had to do any tests like this. Normally we do NASA-STD-8739.4 which basically says continuity, hi-pot, and IR both before and after installation. Then again, there isn't much water up there.

 

[D.A.(Tony)Stewart]

I once had my telephone line fail because of moisture in phone lines along floor in damp basement between studs by some DIY builder.

My thinking is , if your customer specifies that these Type tests must be done, then so be it. Otherwise if cable is compliant, then I would think the test is not needed , but it is designed with materials and process capable of passing.

This might require the cut ends of the jacket to be sealed with Silicone RTV for example, A small amount of water won't cause IR or BDV failure on its own as water is a good insulator but high dielectric constant.

MUddy water on the other hand with minerals is more conductive ( as in my case with light basement flooding) but not called up in the standard as dirty water. Just water. So in my view that means the dielectric constant of 50x for water along the internal jacket may cause sufficient leakage current to cause impedance failure of telephone line and ringer failure as well.

ALthough I have never seen telephone cable siliconed at both cut ends for basement operation, it might be essential for phones to work. ( Remember the days when even when the power failed , at least the phones till operated off CO battery) However it would be nice that the phones would work after the flood water was removed.

None of this is relevent to the question at hand, but puts the problems into perspective. Another example is wiring near boiler tanks and sprinker systems during a fire.

 

[isurunalaka]

has anyone done this test before?

 

[chuckey]

My hairdresser complained about getting tingles from her electric shaver. On closer examination, a single wire from the bundle that make the live conductor had broken during manufacture and was sticking right through the inner insulation and the outer sheath and she sometimes touched it.
So this was an exceptional event but it should have been tested for and picked up in the factory. I guess the more general type test is just to ensure that the manufacture of the cable was properly done.
Frank

 

[Surendhar M]

It is not necessary to use particular water bath to do your test. The test about the cable and not about the water bath. So carry out the test and try to find out if there is any problem with the cable. There is enough suggestions already provided I guess. So lets give a try.

 

[chuckey]

A further thought came to me :- When I worked in wired TV, the system used balanced twisted pairs within a sheath. The sheath was loaded with carbon black to make it "semi conducting" or resistive. The reason for this was that when the cable was installed across the front of houses, dirt would accumulate on its outside causing the cable impedance to change after a couple of years. So it was found that making the sheath conductive to a small degree reduced the change of impedance to a small amount.
So this sort of test would have been very relevant, i.e. to make sure that the resistivity of the sheath met some spec. For mains cable ?, just to stop cable manufacturers cutting corners.
FRank

 

[isurunalaka]

An electric Hot water tank could be improvised to perform this Type test.

You should buy the standard , if you need it.

It is not necessary to use particular water bath to do your test. The test about the cable and not about the water bath. So carry out the test and try to find out if there is any problem with the cable. There is enough suggestions already provided I guess. So lets give a try.

thanks god. at least you have got the standard. what i am asking this water bath. has anyone done the test as mentioned in attached standard doc?