Steel framed workshop.

[bigspark17]

hi have a large workshop to price, standard stuff, but i noticed that the steels 4 of which are not bolted together so in a sense offer 4 earth fault paths, i would plan to export suitable earth/cpc conductor from house to bond the frame but should i bond each steel back to consumer unit(in workshop) or link them together or just bond 1.?
Usually in buildings like this i see that steels are connected together with other steels but on this occasion its timber between.
If i havent explained well i appoligise, but intrested to hear thoughts.

Bigspark17

 

[Martyn Fletcher]

I'm really interested to see what the guru's say about this one, because I'm struggling to even visualise it.
Would have been nice to see a picture.

 

[Deleted member 9648]

You will have to link the steels together with a continuous bond. Don't forget the cpc in the sub to the MET at the intake will need to be at least of the minimum size required for bonding or a separate bond will need to be installed

 

[telectrix]

test each section of the steel to see if it's extraneous i.e. IR test to your MET. if the reading is <22k Ohms, bond them.

 

[Ian1981]

1 protective bonding conductor unbroken to connect to steel , that is if it’s extraneous

 

[Deleted member 9648]

I'm assuming the steels are frames concreted into the ground and hence almost certainly extraneous.....but then again maybe just RSJ's???....confirm please Bigspark.

 

[bigspark17]

I'm really interested to see what the guru's say about this one, because I'm struggling to even visualise it.
Would have been nice to see a picture.

Im sorry my post is not clear but i thought it might not lol. Its about 20M long with 4 x steel A frames but the A frames are segregated, usually i would see cross sections bolted together inbetween A frames thus making them one large extraneous part and only require 1 bond.

You will have to link the steels together with a continuous bond. Don't forget the cpc in the sub to the MET at the intake will need to be at least of the minimum size required for bonding or a separate bond will need to be installed

Yes the sub will be a 16mm 3c, 100A DNO in house so cpc adequate for bonding conductor & cpc house>workshop.

My gut is to link all with an unbroken bonding conductor (10mm) from workshop cu through each steel, just feel is slightly overkill as cant be much Earth fault path resistance from one steel to next.

test each section of the steel to see if it's extraneous i.e. IR test to your MET. if the reading is <22k Ohms, bond them.

Yes the huge steel frame buried deep in the ground is extraneous...

 

[Leesparkykent]

1 protective bonding conductor unbroken to connect to steel , that is if it’s extraneous

Ideally but doesn't have to be unbroken.

 

[Leesparkykent]

If each steel is extraneous and they aren't connected by conductive material then each steel needs bonding. Could be done with one conductor, linking each steel out or seperate conductors back to the EMT. What ever works for your installation/method.

 

[Ian1981]

Ideally but doesn't have to be unbroken.

No but I prefer an unbroken conductor in case one( broken )conductor is removed for whatever reason and you lose continuity to the others.
Just my preference really.

 

[PEG]

Just a thought,but what type of structure,are these A frames?
If they are made up of bolted or riveted sections,you may find you are not bonding all parts,dependant on where you stick your eye terminal.

An assessment of the merits of your bonding,may be needed

Older lattice type steelwork,used in buildings,bridges,over-head cranes,etc is notorious for it's continuity mood-swings.

 

[bigspark17]

Just a thought,but what type of structure,are these A frames?
If they are made up of bolted or riveted sections,you may find you are not bonding all parts,dependant on where you stick your eye terminal.

An assessment of the merits of your bonding,may be needed

Older lattice type steelwork,used in buildings,bridges,over-head cranes,etc is notorious for it's continuity mood-swings.

Bolted brand new A frames, yes they will give full continuity.

What do you mean an assesment of my bonding merits may be needed? If they are extraneous which they are then they need bonding, but my original thought was if you main bonded one wouldnt that be enough?

Im not bonding a bridge or a crane its a steel frames workshop!

 

[PEG]

Bolted brand new A frames, yes they will give full continuity.

What do you mean an assesment of my bonding merits may be needed? If they are extraneous which they are then they need bonding, but my original thought was if you main bonded one wouldnt that be enough?

Im not bonding a bridge or a crane its a steel frames workshop!

Hi,your first line is the answer,then.

My reference to bridges and cranes,was in regard of the type of construction,of steel sections in older pre-fabs,Romney buildings,etc.

I have seen similar structures,with additional supplementary bonding,fitted correctly,frame to frame,stud welded eye terminals,no breaks... but varying or poor readings,as you test along and away,from the bonding.

So,in effect,bonded,but not effectively. It would be a situation such as this,that may require a bonding merit assessment

 

[bigspark17]

Yes well bonding each frame back to EMT will be the answer it just seems overkill as the frames will be giving very similar earth path readings

 

[telectrix]

i just got back from specsavers, got new glasses, steel frames. should i use 6.0mm or 10.0mm bonding cable to my pacemaker?