The measured value of loop Impedance for a circuit is 2.4 Ohms

[Rather be Fishing]

Because it said caravans I've gone to page 265 of the regs and started reading.

Reg 708.415.1 says

(Please see pic)

So does that mean the answer is a) 30ma

Or am I missing something to do with them dropping in TT system in the question along with some test results.

 

[Lister1987]

Because it said caravans I've gone to page 265 of the regs and started reading.

Reg 708.415.1 says

(Please see pic)

So does that mean the answer is a) 30ma

Or am I missing something to do with them dropping in TT system in the question along with some test results.

Working on the basis that this reads as being the main source of supply for the park, (the caravan park bit is a red herring I believe) It is asking about FAULT protection, not Additional (30ma). I'd select 100ma (maximum EFLI 500 ohms, higher than 167ohms for 300ma.

Add the 3 together divide by 3 gives you an EFLI of 407, which is within limits of the 500mA bit outside those of 300mA and 30mA .

Please correct me if I'm wrong ?

 

[Rather be Fishing]

Periodic Inspection and testing of a mobile catering unit is to be carried out as a requirement of the clients insurer?

The supply is from a 3KVA 230V single - phase portable generator and is connected as a TN-S system with fault protection provided by BS EN 61008 30mA RCD

What is the maximum test current applied to the RCD to confirm fault protection is provided.

a)15 mA
b)30 mA
c)60 mA
d)300 mA

You need to understand with regard to a 30ma rcd the difference between fault and additional protection. Knowing this will give you the answer.

I don't know if I've gone to the right place but I've started of at page 55

when I get to reg 411.1 I can see 30mA at the bottom of it and I was told the answer was b) 30mA but I thought I might as well carry on and confirm the difference between fault and additional protection.

In my head

Fault protection is to try to save human and livestock life if there is a electrical fault and they happen to come in to contact with it.

Reading the regs, regulations 411.3.1 and 411.3.2 seem to apply. Protective earthing and Automatic disconnection incase of fault (ADS).

To me this is saying that fault protection is provided by your supplier, all of those typically green and yellow cables (metal conduit or SWA protective strands perhaps). And then the MCB which is already designed and built for you.

Addition protection is that that is Provided by a RCD again designed and built for you and that is required for socket outlets not exceeding 32A and mobile equipment with a rated current not exceeding 32A for use outdoors. reg 411.3.4 adds lights in a domestic premises must also have RCD protection.

Other than seeing 30mA in regulation 411.1 which was on the answers list and not seeing any of the others all the way through to chapter 42 b) 30mA would be the one id have gone for if I had been able to find it in the exam because I couldn't in the mock and went with eni meni d) 300mA. I don't know if someone can help me reassign this 300 figure (maybe ms) to something else in my brain but I'm sure it applies to something because it in there

In my head I've got 1/2x 1x and 5x which is the RCD tests. 30 x 5 is 150mA which isn't on the answers list luckily is higher then 1x 30mA

Is that saying that when you 1x test a RCD you are confirming fault protection.

That just makes me wonder what protection 5x is confirming

 

[Rather be Fishing]

Working on the basis that this reads as being the main source of supply for the park, (the caravan park bit is a red herring I believe) It is asking about FAULT protection, not Additional (30ma). I'd select 100ma (maximum EFLI 500 ohms, higher than 167ohms for 300ma.

Add the 3 together divide by 3 gives you an EFLI of 407, which is within limits of the 500mA bit outside those of 300mA and 30mA .

Please correct me if I'm wrong ?

I'm a bit confused but I like the math's there

Is there a page in the regs that lists the maximum rating of RCD that can be used in fault protection for any given system TT, TNS, TNCS.

I'm just think out loud but would you typically only find those larger rated mA rcd's in a TT system or am I not quite understanding something as they could be found in other places

 

[Rather be Fishing]

Basically I need to store max rating of RCD that can be used for fault protection on a TT system is 300mA and for a TNS is 30mA in my head. ]