DB installed connected & tested

cliffed · May 22, 2018

Just your thoughts on this DB,it’s a Lewden type,I personally don’t like them.
Bus bar,not ideal,main switch on right,space very tight to make connections,hate the rcbo’s,screws in front of each other,making it hard to retighten .

[ElectriciansForums.net] DB installed connected & tested

cliffed · May 23, 2018

Leesparkykent said:
Not double pole but switched neutral. These would of done the job.
Wylex NHXS1B32 32 Amp 30ma Type B 1 Module RCBO - Edwardes - https://www.edwardes.co.uk/en/products/wylex-nhxs1b32-32-amp-30ma-type-b-single-pole-1-module-rcbo-?utm_medium=google_shopping&utm_source=google&utm_campaign=google_shopping&gclid=EAIaIQobChMIxemvxrWc2wIVypPtCh23egO4EAQYASABEgLWBfD_BwE

Agree.

Leesparkykent · May 23, 2018

cliffed said:
Ok,if the fault happens on the 30ma protected circuits,theses would trip before the time delay Rcd.
That’s why the time delay Rcd is installed.
It’s no-different set up than the above literature supplied by the manufacturers.
I can see your points about the N/E scenario,thinking that would be the worst case.
When this set up was introduced years ago,it worked well,preventing complete disconnection, of power.

You are literally talking milli seconds before the upfront RCD trips aswell as the RCBO. what's the installation method of the distribution circuit feeding the loxone?

MFS Electrical · May 23, 2018

cliffed said:
Ok,if the fault happens on the 30ma protected circuits,theses would trip before the time delay Rcd.
That’s why the time delay Rcd is installed.
It’s no-different set up than the above literature supplied by the manufacturers.
I can see your points about the N/E scenario,thinking that would be the worst case.
When this set up was introduced years ago,it worked well,preventing complete disconnection, of power.

Yeah but even when the downstream RCBO trips the N-E fault will still remain and therefore will trip the main RCD after the time delay because the RCBO will only disconnect the line of the CCT the neutral and earth are still in the bars and the fault will be seen by the RCD main switch. IMHO the best way to sort it and achieve discrimination is to change the MCB to an RCBO and have an upfront isolator rather than a main switch.

cliffed · May 23, 2018

Leesparkykent said:
Not double pole but switched neutral. These would of done the job.
Wylex NHXS1B32 32 Amp 30ma Type B 1 Module RCBO - Edwardes - https://www.edwardes.co.uk/en/products/wylex-nhxs1b32-32-amp-30ma-type-b-single-pole-1-module-rcbo-?utm_medium=google_shopping&utm_source=google&utm_campaign=google_shopping&gclid=EAIaIQobChMIxemvxrWc2wIVypPtCh23egO4EAQYASABEgLWBfD_BwE

Agree.

cliffed · May 23, 2018

MFS Electrical said:
Yeah but even when the downstream RCBO trips the N-E fault will still remain and therefore will trip the main RCD after the time delay because the RCBO will only disconnect the line of the CCT the neutral and earth are still in the bars and the fault will be seen by the RCD main switch. IMHO the best way to sort it and achieve discrimination is to change the MCB to an RCBO and have an upfront isolator rather than a main switch.

Yea I can see where everyone is coming from,we are talking about a n/e fault here,I know it’s on aTT system,but realistically
These faults may be happening all the time,on most earthing systems,with negligible currents flowing.
N/e faults have always been a pain,& so be it if all power is disconnected,also if the rcbo disconnects that circuit surely that prevents any fault being on that circuit ie:N/E.,no current will flow to Earth ,arguing the fact the rcbo will trip on a N/E fault.
This is getting mighty confusing.

MFS Electrical · May 23, 2018

cliffed said:
Ok,if the fault happens on the 30ma protected circuits,theses would trip before the time delay Rcd.
That’s why the time delay Rcd is installed.
It’s no-different set up than the above literature supplied by the manufacturers.
I can see your points about the N/E scenario,thinking that would be the worst case.
When this set up was introduced years ago,it worked well,preventing complete disconnection, of power.

Yeah but even when the downstream RCBO trips the N-E fault will still remain and therefore will trip the main RCD after the time delay because the RCBO will only disconnect the line of the CCT the neutral and earth are still in the bars and the fault will be seen by the RCD main switch. IMHO the best way to sort it and achieve discrimination is to change the MCB to an RCBO and have an upfront isolator rather than a main switch.

cliffed said:
Yea I can see where everyone is coming from,we are talking about a n/e fault here,I know it’s on aTT system,but realistically
These faults may be happening all the time,on most earthing systems,with negligible currents flowing.
N/e faults have always been a pain,& so be it if all power is disconnected,also if the rcbo disconnects that circuit surely that prevents any fault being on that circuit ie:N/E.,no current will flow to Earth ,arguing the fact the rcbo will trip on a N/E fault.
This is getting mighty confusing.

even with no current flowing the act of joining the N and earth will trip the rcd try it on a dual rcd board switch off the mcb for say a socket circuit and short N-E the RCD will trip so it makes no difference if the RCBO trips in that board it will still trip the upfront RCD it isn’t compliant with BS7671 if you haven’t achieved discrimination in all fault conditions of final circuits and should be noted as a departure on the EIC along with an attached risk Assessment

cliffed · May 23, 2018

That applies to all time delay DB’s.If the mcb is changed to a rcbo,then a main switch installed,IMO,that’s makes it worse,N/E remains.

MFS Electrical · May 23, 2018

cliffed said:
That applies to all time delay DB’s.If the mcb is changed to a rcbo,then a main switch installed,IMO,that’s makes it worse,N/E remains.

But it will still only trip the affected CCT the fault will remain until rectified but the the circuit will not be able to be energised which should mean that no dangerous current should flow from nuetral to earth

cliffed · May 23, 2018

Agree

Deleted member 26818 · May 23, 2018

Ideally, you should swap the RCBOs in the Lighting panel for MCBs, swap the 63A MCB for an RCBO and swap the upfront RCD for a main switch.
Then again, is it really worth it?

ipf · May 23, 2018

rolyberkin said:
My issue with the Lewden boards is the advised torque settings, I have two torque drivers and with either if I torque them to manufacturers settings it has a tendency to damage the rcbo screws.

Never had a torque driver...and never had a problem.
We should go back to double screwed terminals.....it'd give everybody two chances of getting at least one right. Like these, maybe.

MFS Electrical · May 23, 2018

ipf said:
Never had a torque driver...and never had a problem.
We should go back to double screwed terminals.....it'd give everybody two chances of getting at least one right. Like these, maybe.
View attachment 42407

Gotta love the old Wylex boards

actually I think Wylex are returning to double screws for the tails anyway

ipf · May 23, 2018

MFS Electrical said:
Gotta love the old Wylex boards actually I think Wylex are returning to double screws for the tails anyway

......with main switch on the right, of course.

MFS Electrical · May 23, 2018

MFS Electrical said:
Gotta love the old Wylex boards

ipf said:
......with main switch on the right, of course.

nah that bugs me you don’t read from right to left do you?

Rpa07 · May 23, 2018

是

MFS Electrical said:
nah that bugs me you don’t read from right to left do you?

DB installed connected & tested

cliffed

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cliffed

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Leesparkykent

MFS Electrical

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cliffed

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cliffed

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MFS Electrical

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cliffed

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MFS Electrical

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cliffed

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Deleted member 26818

ipf

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MFS Electrical

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ipf

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MFS Electrical

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Rpa07

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