Help needed please

[Hp1]

Hi,

I would be grateful if anyone could advice me on the following.

When carrying out a PIR, I found a Proteus Consumer unit. The Main Switch was 100A BS5419:1977 240V/415V AC22. The MCB's were Type 2 M6. Also the Mains supply fuse was a rewirable type, it was housed in a metallic carrier with the words " The Property of the METESCO Compan". It did not have any Current value on the fuse carrier or housing.

My questions are:-
1/ What do I write as the Supply protective device characteristics on the PIR form is it Bs3036? also how do I ascertain the size of the fuse current rating (looks about 63A).

2/ What is the Short circuit capacity in KA of the overcurrent device? (no indication on the Switch).

3/ what tables do we use to check that the maximum earth loop impedance values are acceptable? (i.e do we use table 41B2 inthe wiring regs, bearing in mind this is only for type B/C/D circuit breakers and the consumer unit has type 2 circuit breakers).

4/ when did they change from using BS5419:1977 to using BS EN 60439-3 for the main switch.


Kind Regards

Harry

 

[Spark123]

For 3/ you need to consult the tables in the back of guidance note 3.

 

[RF Lighting]

1/ What do I write as the Supply protective device characteristics on the PIR form is it Bs3036? also how do I ascertain the size of the fuse current rating (looks about 63A).

Yes it is a BS3036 fuse.
The fuse rating may be on the cover of the cutout, or may be written on the asbestos liner inside the cast iron lid of the cutout, but experiance and looking at the thickness of the wire is the only real way to tell for sure.

Most BS3036 cutout fuses are only 30A

2/ What is the Short circuit capacity in KA of the overcurrent device?

BS3036 fuses usually have a Short circuit capacity of 3kA

(no indication on the Switch)

On which switch? Do you mean the cutout?

3/ what tables do we use to check that the maximum earth loop impedance values are acceptable? (i.e do we use table 41B2 inthe wiring regs, bearing in mind this is only for type B/C/D circuit breakers and the consumer unit has type 2 circuit breakers).

Yes, use table 41B2. As the circuit breakers are type 2, then they will almost certainly be BS3871 circuit breakers, not BSEN60898, so you should use part (f) of table 41B2

4/ when did they change from using BS5419:1977 to using BS EN 60439-3 for the main switch.

Not sure. Why do you need to know this?

 

[Hp1]

Hi spark123,

Thank you for your response. The table 2D in the back of the guidance notes 3 does show mcb's type 1/2 and 3. It mentions this table is to be used when the overcurrent protective device is an mcb to BS 3871. Are all type 1 2 and 3 mcb's always to BS3871? the mcb's in the consumer unit did not show the BS number.

Once again thanks for your help.

Harry

 

[fireman22]

harry, i thought main switch was 60947-3?

 

[Spark123]

I think so, it should tell you if you extract the MCB somewhere. The M6 will be referring to a 6KA breaking capacity which makes me think they are. The GN3 tables are 80% values for max measured whereas the regs are design values.

 

[RF Lighting]

harry, i thought main switch was 60947-3?

I've seen both BSEN60947-3 and BSEN60439-3.

the BSEN60947-3 are most common, but one of the bigger manufacturers use BSEN60439-3 main switches (I think it might be Hager but I can't remember off hand)

 

[Hp1]

Hi RF Lighting,

Thank you for your response.

Yes it is a BS3036 fuse.
The fuse rating may be on the cover of the cutout, or may be written on the asbestos liner inside the cast iron lid of the cutout, but experiance and looking at the thickness of the wire is the only real way to tell for sure.

Thank you. However, the rating was nowhere to be seen. The fusewire looked thicker than normal 30A wire we normally use. Does fusewire come rated to 63A?

Regarding the short circuit capacity. I was expecting the short circuit capacity of the main BS5419 100A switch (in the CU) to be shown on the device (normally 6KA).

Yes, use table 41B2. As the circuit breakers are type 2, then they will almost certainly be BS3871 circuit breakers, not BSEN60898, so you should use part (f) of table 41B2

Table 41B2 part (f) is for type c circuit breakers to BS EN60898? (or am I loosing the plot). I was looking at table 2D part (11) on page 114 Guidance notes 3 (this mentions mcb's to BS3871 (as you mention)

Not sure. Why do you need to know this?

just curious.

by the way when you guys go to do a PIR and the service fuse is sealed and there is no indication on the fuse carrier as to the current rating or type of fuse (BS number etc) what do you write on the PIR certificate/record

Thank you very much for your help it is greatly appreciated.

Kind Regards

harry

 

[Hp1]

Hi Fireman22,

harry, i thought main switch was 60947-3?

Generally the main switch is BS EN 60947-3 but the main switch in the Poteus CU is definately BS5419:1977 (looks like a predecessor to the 60947-3).

hi spark123,

think so, it should tell you if you extract the MCB somewhere. The M6 will be referring to a 6KA breaking capacity which makes me think they are. The GN3 tables are 80% values for max measured whereas the regs are design values

Yes I think you are right the M^ must be the breking capacity for the mcb's. However the main switch did not mention M6. It did mention AC22, what does this mean?

Would also be grateful if you guys could inform me what you write on PIR for supply fuse if the carrier is not marked up and the fuse carrier is sealed.

RF Lighting Thank you for your information.

Kind regards

harry

 

[RMS]

fuse wire diameter for -30A is 0.85mm
-60A is 1.53mm
-80A is 1.8mm
-100A is 2mm

 

[Hp1]

hi RMS,

Thank you very much, will check diameter next couple of days. Do you know if the service fuse was commonly supplied in 60A, 80A and 100A in rewirable format?

Kind regards

Harry

 

[RMS]

Only been carrying out periodic inspections for a couple of years and never come across a BS3036 service fuse so have never had to ascertain that information. Its probably going to be less than 60A i would think.

 

[Hp1]

Hi RMS,

On recollection, the fuse wie was definately thicker than 30A fusewire (visual comparism, did not have a vernier micrometer handy). I think it may have been approximately 1.5mm thick.

I am also fairly green to Periodic inspections within the domestic environment. Must be jinxed (comming across one so soon!!).

Thanks very much for your help.

Harry

 

[RF Lighting]

Thank you. However, the rating was nowhere to be seen. The fusewire looked thicker than normal 30A wire we normally use. Does fusewire come rated to 63A?

Fuse wire is (was anyway, don't know if it still is) available in 5A, 15A, 20A, 30A, 45A, 60A, 80A & 100A (and 6" nail amps)

Regarding the short circuit capacity. I was expecting the short circuit capacity of the main BS5419 100A switch (in the CU) to be shown on the device (normally 6KA).

Main switches do not have a kA rating. This only applies to fuses and MCBs

Table 41B2 part (f) is for type c circuit breakers to BS EN60898? (or am I loosing the plot). I was looking at table 2D part (11) on page 114 Guidance notes 3 (this mentions mcb's to BS3871 (as you mention)

According to my regs table 41B2 section (f) is for 'Type 2 minature circuit breakers to BS 3871'

What colour is the cover on you regs?

by the way when you guys go to do a PIR and the service fuse is sealed and there is no indication on the fuse carrier as to the current rating or type of fuse (BS number etc) what do you write on the PIR certificate/record

You can tell the type from the style of the cutout.
As for the current rating you cannot tell. You can enquire from the supply company, or I guess put an estimated value.

However the main switch did not mention M6. It did mention AC22, what does this mean?

AFAIK AC22 is merely a part number.

Thank you very much, will check diameter next couple of days. Do you know if the service fuse was commonly supplied in 60A, 80A and 100A in rewirable format?

I have only ever seen them rated to 30A in a domestic cutout.

 

[Hp1]

Hi RF Lighting,

According to my regs table 41B2 section (f) is for 'Type 2 minature circuit breakers to BS 3871'
What colour is the cover on you regs?

My Regs are coloured Brown. Bs7671:2001 incorporating Amendments No 1:2002 and No 2:2004. Table 41B2 is on page 46 but part (f) definitely says Type C circuit breakers to BS EN 60898 and RCBO's to BS EN 61009. which version/colour of the regs do you hold?

Thank you for your time in replying, It has been greatly appreciated and very informative

Kind Regards

Harry