TT high ze - rcd tripping

[ash_s3]

Had a look at a fault for a mate, cooker kept taking out main 30mA rcd when switched on at cooker switch (no load, just turning on at wall)

Disconnected cooker, turned on all ok. Cooker faulty? Had it tested and it was fine.

Tested circuit, megger, r1+r2, all perfect. Went to do zs and got a reading of 460ohms!

Checked ze at db and was very similar, did ramp test on rcd and its tripping at 15mA.

Traced the 10mm earth (all surface clipped) and it disappears under a paving slab.

Will having a high ze cause the rcd to operate early or not?

I'm going to install a new earth road in the week, will try and get hold of a General Electric main switch/rcd but im not sure who would get hold of one?

Cheers

Ash

 

[topquark]

High Ze more likely to make it fail to work. If it's threashold is 15mA then bin it and replace it anway, then start testing again. You often find that the RCD is the cause of the high Zs IF the Ze is OK (but not in this case).

 

[IQ Electrical]

Had a look at a fault for a mate, cooker kept taking out main 30mA rcd when switched on at cooker switch (no load, just turning on at wall)

Disconnected cooker, turned on all ok. Cooker faulty? Had it tested and it was fine.

Tested circuit, megger, r1+r2, all perfect. Went to do zs and got a reading of 460ohms!

Checked ze at db and was very similar, did ramp test on rcd and its tripping at 15mA.

Traced the 10mm earth (all surface clipped) and it disappears under a paving slab.

Will having a high ze cause the rcd to operate early or not?

I'm going to install a new earth road in the week, will try and get hold of a General Electric main switch/rcd but im not sure who would get hold of one?

Cheers

Ash

The answer to your question is no, having a high Ra and consequently a high Zs (460 Ohms is not abysmal on a TT system if it is fairly constant and has 30mA protection) will not cause early operation of the RCD.

I know you say you had it tested but my money is still on a cooker fault (maybe intermittent).

 

[topquark]

Yep, I'd try testing the cooker again when it's hot, I've seen that before where it IR (PAT) tests fine when cold, but fails when hot.

 

[ash_s3]

The cooker was taken away to a specialist for testing and a replacement dropped off while it was away. The replacement also caused tripping problems. Doesn't do it every time just randomly!

Any suggestions on where to find a GE 30mA 80a DP RCD? or will an alternative fit?

 

[mark1979]

http://www.****************/shop/d190/sd3096/switchTaxY

google search.

 

[Engineer54]

The answer to your question is no, having a high Ra and consequently a high Zs (460 Ohms is not abysmal on a TT system if it is fairly constant and has 30mA protection) will not cause early operation of the RCD.

you say you had it tested but my moneI know y is still on a cooker fault (maybe intermittent).

Not with an RCD tripping out on 15mA... As Topquark, says it needs replacing!!

 

[ash_s3]

Right guys, I'm struggling to get hold of a GE rcd. Can anyone help? Anyone know of a suitable replacement?

Cheers
Ash

 

[Guest123]

http://products.geindustrial.com/IndustrialProducts/Dispatcher?REQUEST=TECHNICALSEARCH&CATALOG=PP&lang=en_GB&PRODUCT_SUB_FAMILY=ELFA_PP


Try the search facility above.

 

[Deleted member 9648]

Right guys, I'm struggling to get hold of a GE rcd. Can anyone help? Anyone know of a suitable replacement?

Cheers
Ash

....Looks like a standard 2 pole din mounted 61008 RCD....probably pretty much any one will fit.

 

[steamboatwilly]

Much as it pains me to say it there are some on eBay. There are a few on Google if you just search for "GE RCD".

 

[ash_s3]

Tried google first, can't fine on that looks the same.
eBay has one but it's second hand and I'm dubious about fitting second hand parts.

This is the rcd in question