Zs on a storage heater

[martinh89]

Hi could some one help me out, im taking my 2394 next week and ive been told to expect questions similar to the heading of this thread.

My questions are :
How would you perform an insulation resistance test on a storage heater (my confusion is with the element, will 500v damage it ect...)

And how wouldyou perform a zs test? I know its a live test and if i did it at the consumer unit i would contridict reg 14 of EWR so would a calculated result be acceptable? Zs=ze+(R1+R2)

Cheers

 

[gazj82]

I would calculate Zs on a night store, or do you plan to come back at midnight to measure it?

 

[AndyL]

500v test voltage will not damage the element but you will get a reading of the element resistance. You would therefore test between live conductors and earth only, not between live conductors.
You can calculate Zs as mentioned, but if they are asking you to measure it then you need to describe that.

 

[martinh89]

I would calculate Zs on a night store, or do you plan to come back at midnight to measure it?

Its not a job mate its just a question i think i might come across in the test and that i wasnt really sure of.

Cheers for the replys

 

[rozzerboy]

Sounds like a question from the last exam?

 

[Silly Sausage]

500v test voltage will not damage the element but you will get a reading of the element resistance. You would therefore test between live conductors and earth only, not between live conductors.
You can calculate Zs as mentioned, but if they are asking you to measure it then you need to describe that.

Trouble here is, 2394 is Initial Verification, so IR tests needs to be done between ALL conductors.
You would need to isolate the storage heater.

 

[Badged01]

As above for IR tests. If its initial verification (2394) in its true form then you shouldnt have any power on to isolate until you have done all the dead tests -- which includes IR across all conductors (without storage connected?!?)

And Im also puzzled why you would IR a storage heater on initial verification? I assume its a new piece of kit which wont need doing, or if "pre-loved" and being connected up, should have had a simple 'PAT' done beforehand. (Which I believe doesn't fall within the requirements of initial verification??)

Or maybe the whole initial verification syllabus has changed and I need to go back to night skool!!

p.s. Zs can be calculated or measured. There are arguments for both sides of the camp.

 

[rozzerboy]

From what i remember, the question was based on an install of storage heaters and new circuits wired for the heaters and how would you do an IR test at the board?

 

[cobrauk]

We only test the hard wiring not appliances , they would come under PAT testing, so turn off the DP Isolator at the heater to test the circuit only.

Zs can not be done unless you come back on the night shift so just show that as a LIM on the form

 

[Jay Sparks]

We only test the hard wiring not appliances , they would come under PAT testing, so turn off the DP Isolator at the heater to test the circuit only.

Zs can not be done unless you come back on the night shift so just show that as a LIM on the form

You cant have a LIM on an EIC. For the Zs, you would have to contact the distributor for the Ze, then add it to your R1 + R2 readings and hey presto.

Jay

 

[shanky887614]

You cant have a LIM on an EIC. For the Zs, you would have to contact the distributor for the Ze, then add it to your R1 + R2 readings and hey presto.

Jay

Or what a lot do and disconnect main earth and test yourself then calc zs reading

 

[Jay Sparks]

Or what a lot do and disconnect main earth and test yourself then calc zs reading

But how can you do that on an E7 board????? Unless you go back late at night to test it!! I suppose you could test the the 24 hr cu as it will be nearly the same but thast not what the question is asking. Its Initial verification on E7 storage heaters.