Opinions

[Eire79]

Ok contractors on site have jointed a existing 4x70 to a new 4x70 to extend onto a chemical process panel and I was testing same today . Phase resistance is .03 and Pe is .10 so all good . I opened j box to discover both cables glanded ok and banjos linked via 10sq and bolted with gutter bolts which I hate as I said they belong on gutters not electrical connections. Then at chemical panel they glanded the cable in panel loose and took a 16sq on the dreaded gutter bolt again down to the earth bar .
So my issues are the gutter bolts , 10 sq and 16 as earth tails which I would myself use a 35 sq as it's half the phase conductor or do you think the 10 16 sq is ok given it length is so small the the resistance in very low . They also intersepted a high level earth bar which was for local bonding and took a 35sq to the chemical panel which did bring the fault loop from .10 down to .03 , what would be your taughts on this .

 

[ipf]

I can't see anything wrong with the earthing/bonding, if it's all lugged correctly. Main sub frame of a building is the best earthing available, if correctly bonded, except at the incomer.
Are the gutter bolts you refer to roofing bolts? If so, I agree with you and wouldn't use them. However, if they do the job intended it's just another example of how 'some' do things, these days.

 

[davesparks]

There seems to be a lot of guesswork going in to the size of the cpc needed here!

Someone should have calculated the size of the CPC required and that size should have been used.

If the gland has been fitted loose that is unacceptable.

Your comment about the 10mm section being short and of low resistance doesn't make sense, the required size needs to be calculated to ensure it can safely handle the maximum fault current for the circuit, not just to have a low resistance.

 

[ipf]

Why the glanding loose, is there an access problem?

 

[Eire79]

Why the glanding loose, is there an access problem?

Its a panel that has a floor with openings to allow cable entries , its more a control cabinet than a distribution board with the isolator in the bottom left side . If a bit of taught went into it it could have been done better .
i have done similar myself by top entry and cleating the cable down the inside.
just to note side entry was not an option as other equipment is either side of it although a back entry would have been possible if a entry was then cut through the internal plate holding all the control equipment.
[automerge]1592602396[/automerge]

There seems to be a lot of guesswork going in to the size of the cpc needed here!

Someone should have calculated the size of the CPC required and that size should have been used.

If the gland has been fitted loose that is unacceptable.

Your comment about the 10mm section being short and of low resistance doesn't make sense, the required size needs to be calculated to ensure it can safely handle the maximum fault current for the circuit, not just to have a low resistance.

I am in Ireland and rules here state the the cpc should be at least half the size of the phase conductor that's why I had issue with the 10 sq. bridge as its a weak point, it would have been much easier if the banjos had been bolted together and gland properly glanded to the control panel.
He got a bit offended by my comments on his work and started on about the rest of the plant in general and its condition , but that is another issue totally separate to their installation which in fact they will have to certify .
so at the end of the day its his name on the cert. I think a e mail stating the issues should be drafted and sent at this stage to the engineering dept and let them sort it out as they will be paying the bill.
[automerge]1592602711[/automerge]

I can't see anything wrong with the earthing/bonding, if it's all lugged correctly. Main sub frame of a building is the best earthing available, if correctly bonded, except at the incomer.
Are the gutter bolts you refer to roofing bolts? If so, I agree with you and wouldn't use them. However, if they do the job intended it's just another example of how 'some' do things, these days.

True I agree , I always use a proper bolt to connect earths , in fact the newer part of plant its all brass bolts and nuts that were used for earthing and bonding.

 

[ipf]

Its a panel that has a floor with openings to allow cable entries , its more a control cabinet than a distribution board with the isolator in the bottom left side . If a bit of taught went into it it could have been done better .
i have done similar myself by top entry and cleating the cable down the inside.
just to note side entry was not an option as other equipment is either side of it although a back entry would have been possible if a entry was then cut through the internal plate holding all the control equipment.
[automerge]1592602396[/automerge]

I am in Ireland and rules here state the the cpc should be at least half the size of the phase conductor that's why I had issue with the 10 sq. bridge as its a weak point, it would have been much easier if the banjos had been bolted together and gland properly glanded to the control panel.
He got a bit offended by my comments on his work and started on about the rest of the plant in general and its condition , but that is another issue totally separate to their installation which in fact they will have to certify .
so at the end of the day its his name on the cert. I think a e mail stating the issues should be drafted and sent at this stage to the engineering dept and let them sort it out as they will be paying the bill.

I see what you mean now. Your action seems OK, given the circumstances.
I'm not surprised he's offended.....that's the way a lot of 'em work, these days.
Looks like he's just OK on the swa, size wise.

 

[davesparks]

True I agree , I always use a proper bolt to connect earths , in fact the newer part of plant its all brass bolts and nuts that were used for earthing and bonding.

They don't always have to be brass, and a brass bolt won't always achieve the same clamping pressure as a steel bolt.

This is why the terminal bolts/screws in the majority of switchgear and DBs aren't brass.

Personally I try to always use earthing nuts with SWA as I think it gives a much better connection and banjos these days appear to be far too thin and flimsy.

 

[ipf]

It baffles me how many times you find unbolted banjos fitted.
Maybe for future, it can always be fitted if it's there, I suppose.

 

[Lucien Nunes]

They don't always have to be brass, and a brass bolt won't always achieve the same clamping pressure as a steel bolt. This is why the terminal bolts/screws in the majority of switchgear and DBs aren't brass.

From the point of view of accessory manufacturers, if steel will do, its lower cost is a definite plus. As an actuator for a rising clamp terminal where the screw is not the main current path to the conductor, it may well be a better choice.

However, I would not use steel hardware anywhere it is likely to corrode or induce corrosion in the connected parts, or when connecting only brass or copper parts. For these I would always choose brass, preferably nickel-plated, to ensure low and stable contact resistance even where superficial corrosion might take place. If the hardware is correctly sized for the job, one can get ample clamping force using brass, which cannot always be said of a cheap roofing bolt and square nut with badly formed threads and a shallow head.