Measuring residual current. How do I know what RCD to fit?

[GMES]

So why is he not listening to your professional opinion?

This is the thing Dillb, the boss may be asking for rcd's but as the electrician surely it would be our job to sit him down and tell him the correct way of doing it.

 

[netblindpaul]

Simple answer.
Get the "boss" to design the install, and sign for it, you install and test to his spec, and put notes to the cert with regard to your reservations, job done.
He thinks he knows better so, get him to put his signature where his mouth is.
IF he is registered with one of the Engineering Institutes, and he works outside his area of competence, or works incompetently then there can be ramifications.
Plus the HSE would not take it lightly if something went wrong, with him being a registered Professional Engineer.

 

[Badged01]

So why is he not listening to your professional opinion?

The ego of management usual far outweighs their intellectual capacity to understand the simple .... or to save face, I said to do it this way so JFDI

 

[infinity]

I have a megger earth leakage tester, very accurate! About £300!

 

[Knobhead]

You can’t beat having a mechanical bod as senior engineer:
They have to do what you say.
You do what you want to do.
Get the cheque book out when you want something, so long as you make it sound plausible.
Haven’t a clue what you’re doing most of the time so can’t ask awkward questions.
What more do you want?

The down side, when it all goes wrong you’re the first to get an invite to the arse kicking party. If they’re anything like mine, he’ll be on holiday the day of the party.

 

[Inteificio]

The boss does listen to me, I'm lucky I have one of the rational ones.

If he doesn't agree with something, he asks me to explain it (admittedly not always in the nicest of ways). If I have demonstrated that I have thought it through we always do it my way (if i'm willing to argue). Much better than the !"£$"! he replaced.

This is one of the reasons why electrical safety is now being taken so seriously is because I insisted on it.

One of the standards I insisted on is everything should be RCD protected, not just when regs dictate. It should be 30mA, unless this causes nuisance trips, then it will be fitted with the lowest level rcd that will not trip. The machine will then have it's own dedicated and labelled socket and only that machine is to be plugged in to that socket.

I can't exactly ignore the standard I introduced can I?


Can we view this the other way around:

1: Why would I want to exclude RCDs from the design?

actually, I only had that one question...


As for linking all the machines together, I'm not a huge fan. However I can see the significant advantages. It will just be a pain to design and install.

While I'm here has anyone used Epic connecters, I've not looked to close, but they seem to be alright?

Buy Heavy Duty Power Connectors HBE 6 2 Male Right Angle Heavy Duty Power Connector, Panel Mount 16A,600V Epic Contact 70250205 + 10190000 online from RS for next day delivery.

 

[Inteificio]

I have a megger earth leakage tester, very accurate! About £300!

Thanks for the offer, but we have a weird buying policy at our place.

 

[itselectric]

If you're so intent on using RCD's then an upfront one would not be the way to go. One machine develops a fault they all go down, then the time taken to find the machine causing it, causes longer downtime. I, like others, think RCD is not the way to go, but if you are going that way then RCD individual machines, more expensive install but quicker fault find = less downtime

 

[Engineer54]

Thanks for the offer, but we have a weird buying policy at our place.

Don't think he was offering his leakage tester for sale!! lol!!

 

[Engineer54]

I have a megger earth leakage tester, very accurate! About £300!

There are models just as accurate, eg with the same resolutions etc, at around half the cost of the megger... This one for instance is hard to beat for the money!!

TM-EL9809 High Resolution AC Earth Leakage Clamp Meter

 

[Robotstar5]

Why not install a plug in busbar system above the production line, then just plug in tapoff boxes for each machine. You can add, remove or move machines easily in future.

 

[Guest111]

Sometimes you've got to hold your ground,we'd a company director who designed at IT system for the firm I worked at,now I was the only one who knew anything about Data and networking and it was obvious at a glance that his system wouldn't work.We ended up having a huge shouting match,him giving it the old " I pay your wages so you'll do as I say" bit then me having a go back and telling him to get a contractor in 'cause his way was wrong and he was a 2 faced git and I'd end up taking the flak when it didn't work.Anyway in the end I got my way and did the job how it should have been done,but the best thing was that in the end the director not only saw his way was wrong but openly admitted it! Still there's a first time for everything.

 

[Badged01]

..... the best thing was that in the end the director not only saw his way was wrong but openly admitted it!

You're lucky! Normally they just hold the grudge and get you back at some point ...... saving face can have strange effects on people!!

 

[sibbits]

Why not install a plug in busbar system above the production line, then just plug in tapoff boxes for each machine. You can add, remove or move machines easily in future.

ive done just the thing in the place where i ,work tap off boxes with their own individual mcbs which feed the machines so if one need to go off site for servicing or whatever .
works a treat.

 

[Engineer54]

Unless this production line is operating in a wet or very damp conditions, RCD protection can be more problematic in service than it's worth. The idea of installing a plug-in busbar system is probably the best solution suggested to date, and should solve the majority of your concerns... They can be installed for best utilisation above, on or below the production line....

 

[netblindpaul]

Try upgrading a machine for one with VSD's or better still regenerative servo drives and see if your RCD holds then!

DOn't do it, fixed industrial machinery should be just that fixed & hard wired.
RCD's have no place there.
The design of the containment and supply wiring should circumvent the possibility of any mechanical damage that would require and RCD.

Plus you would end up going against manufacturers instructions with a lot of kit, it you did this.

 

[TheMosquitoKing]

Would RCBOs not be the best option here?