Hi
I am a sparks from the 15th Ed, did 16, 17 and last year 18th. I am out of practice though as have been office based for 12+ years in a different industry with only doing minor stuff for myself (in conjunction with Building Control) and minor non-domestic works.
Like many I may have to dust off my tool to ride out Covid. No issue have been doing bits and bobs throughout that time. Down to the Qs.
The Situation
A friend of mine is undergoing some building changes on his farm (no animals). I am looking at combing two boards that have been installed at separate times over the last 20 years, into one board and moving it to an adjacent wall, extending circuits as needed. Both boards have an inbuilt Triple Pole isolator, with neutral not isolated.
The building is one of many on site, it is a large 15m x 30m metal building, Concrete slab, insulated metal sheets etc - used as a vehicle repair workshop. RS doors and single leaf doors for entry. Only trained, competent persons will be using the building.
The install is over 25 years old, not done by me
. It is part of a larger system of buildings, fed from a central meter room in a separate building. Supply to site is via TNCS into a single meter.
In the building i am dealing with, he has an oil heater, supplied from a plastic tank about a meter away from the building outside, via a copper pipe running in the lower Purlin (at no point goes in the ground). This is not bonded on entry. There is water supply, but this is a blue plastic pipe out of a duct into the building.
There is a very old 3 phase welder fed via TP (no neutral) 20A breaker. This is said to trip sometimes - MCB is not C rated, no RCD neither – not investigated this yet.
There is a TPN red commando type socket (rated 16A) fed via 25A TP RCD breaker on a smaller board, protected by 32A Breaker in the main board ( i think this was added by the owner.) This is used for a ground based hoist.
There is one 63A TP breaker, that supplies a separate building, which again then goes on to supply a small metal building over 200m away used as a 'snug'. A N Other sparks sorted that. It has an earth steak at the snug end.
A TP Lathe, another car hoist, TP compressor etc.
I should point out that there is Single phase Generator on site that, in the event of a mains failure, will supply essential services in all buildings: local rings, lighting CCTV and Intruder etc. Each building has one of these boards installed and a few years back, circuits were removed from the local boards and installed on these Generator fed boards. I will have to move the generator board for this building onto another wall, but I am not adding or removing circuits. I will of course ensure circuits are correct.
None of the SWA have a Banjo earth arrangement, they are just glanded into the metal - No piranha gland neither.
Conductors are all reds and blacks, some plastic conduit some SWA, and one or two blues and browns from later additions by other sparks.
Once i have finished we will get a sparks with all the test kit to come in and test it, i just don’t have anything in calibration any more.
I am not 100% sure about the size of the conductors used. When I was last on site with my head in eth board. I am embarrassed to say i was unable to tell by looking at conductors if they were 10, 16 or 25mm. I have since been to the Wholesaler and got some samples so I can check and record cable sizes.
Please correct me if i am wrong, IMHO I will need to: -
Check IB for all circuits and ensure correct cable sizing, breaker selection etc for each of the circuits amend as required.
I will be fitting RCBOs where ever possible - welder may be an issue.
Check supply cable to this board is correctly sized given the load of the system.
Add notices about mixed conductor colour coding.
Install piranhas / banjos for all SWAs to ensure good earth continuity into the board.
Bond the metal pipe from the oil tank.
Maintain bond to the structure of the building.
Ensure that SWA at the ‘Snug’ is not attached to the earth stake at the ‘Snug’.
I will be going back to confirm loads on the various machines and cable sizes, length of runs etc. In my day i was mostly single phase. The last time i did any three phase work was during my C -Course!!! So will be looking into how calculate current for a Three phase load. PF correction will not be required.
Concerning diversity, there are no more than two people in the workshop at once. For the supply cable, I am not sure how I can work this in. Under no circumstances will all machines be going at once. Any thoughts on how i can apply this please?
Yes i know it is a lot to take on for an old has been now wannabe, but i have time to do it right.
Thanks
John
I am a sparks from the 15th Ed, did 16, 17 and last year 18th. I am out of practice though as have been office based for 12+ years in a different industry with only doing minor stuff for myself (in conjunction with Building Control) and minor non-domestic works.
Like many I may have to dust off my tool to ride out Covid. No issue have been doing bits and bobs throughout that time. Down to the Qs.
The Situation
A friend of mine is undergoing some building changes on his farm (no animals). I am looking at combing two boards that have been installed at separate times over the last 20 years, into one board and moving it to an adjacent wall, extending circuits as needed. Both boards have an inbuilt Triple Pole isolator, with neutral not isolated.
The building is one of many on site, it is a large 15m x 30m metal building, Concrete slab, insulated metal sheets etc - used as a vehicle repair workshop. RS doors and single leaf doors for entry. Only trained, competent persons will be using the building.
The install is over 25 years old, not done by me
. It is part of a larger system of buildings, fed from a central meter room in a separate building. Supply to site is via TNCS into a single meter.In the building i am dealing with, he has an oil heater, supplied from a plastic tank about a meter away from the building outside, via a copper pipe running in the lower Purlin (at no point goes in the ground). This is not bonded on entry. There is water supply, but this is a blue plastic pipe out of a duct into the building.
There is a very old 3 phase welder fed via TP (no neutral) 20A breaker. This is said to trip sometimes - MCB is not C rated, no RCD neither – not investigated this yet.
There is a TPN red commando type socket (rated 16A) fed via 25A TP RCD breaker on a smaller board, protected by 32A Breaker in the main board ( i think this was added by the owner.) This is used for a ground based hoist.
There is one 63A TP breaker, that supplies a separate building, which again then goes on to supply a small metal building over 200m away used as a 'snug'. A N Other sparks sorted that. It has an earth steak at the snug end.
A TP Lathe, another car hoist, TP compressor etc.
I should point out that there is Single phase Generator on site that, in the event of a mains failure, will supply essential services in all buildings: local rings, lighting CCTV and Intruder etc. Each building has one of these boards installed and a few years back, circuits were removed from the local boards and installed on these Generator fed boards. I will have to move the generator board for this building onto another wall, but I am not adding or removing circuits. I will of course ensure circuits are correct.
None of the SWA have a Banjo earth arrangement, they are just glanded into the metal - No piranha gland neither.
Conductors are all reds and blacks, some plastic conduit some SWA, and one or two blues and browns from later additions by other sparks.
Once i have finished we will get a sparks with all the test kit to come in and test it, i just don’t have anything in calibration any more.
I am not 100% sure about the size of the conductors used. When I was last on site with my head in eth board. I am embarrassed to say i was unable to tell by looking at conductors if they were 10, 16 or 25mm. I have since been to the Wholesaler and got some samples so I can check and record cable sizes.
Please correct me if i am wrong, IMHO I will need to: -
Check IB for all circuits and ensure correct cable sizing, breaker selection etc for each of the circuits amend as required.
I will be fitting RCBOs where ever possible - welder may be an issue.
Check supply cable to this board is correctly sized given the load of the system.
Add notices about mixed conductor colour coding.
Install piranhas / banjos for all SWAs to ensure good earth continuity into the board.
Bond the metal pipe from the oil tank.
Maintain bond to the structure of the building.
Ensure that SWA at the ‘Snug’ is not attached to the earth stake at the ‘Snug’.
I will be going back to confirm loads on the various machines and cable sizes, length of runs etc. In my day i was mostly single phase. The last time i did any three phase work was during my C -Course!!! So will be looking into how calculate current for a Three phase load. PF correction will not be required.
Concerning diversity, there are no more than two people in the workshop at once. For the supply cable, I am not sure how I can work this in. Under no circumstances will all machines be going at once. Any thoughts on how i can apply this please?
Yes i know it is a lot to take on for an old has been now wannabe, but i have time to do it right.
Thanks
John
