Question regarding 4 pole MCB

[martinh287]

Have to say a 30mA 4 pole main incomer is cutting it close to the bone but if you havent had any nuisance tripping with it. Why change it. As you say its tested regularly with no problems.


It does surprise me the welder not tripping the rcd though

 

[44ALLAN]

Have to say a 30mA 4 pole main incomer is cutting it close to the bone but if you havent had any nuisance tripping with it. Why change it. As you say its tested regularly with no problems.


It does surprise me the welder not tripping the rcd though

Well I have the same scenario with our new 15Kw compressor.
It has a variable speed inverter...........now how many times have you heard never use an rcd on an inverter ?
The feed to this has 30mA protection.
I asked the guy installing it about rcd protection and he said why not try it and see..........if it trips and you get hassle then take it out.
It's been running for 3 month now no worries and the circuit is far safer with ADS and RCD protection in my humble opinion but what do I know eh .

 

[Engineer54]

Why would it be shot?
It's tested on a regular basis the same as all my equipment!!!.....seems you can't resist having a dig at folk mate !!

Before you start throwing your rattle out of the Pram, perhaps you should Remember what you have previously posted on this thread!! (post #14)

As a reminder....

( maybe I should test them they might all be stuck eh!! )

We can only be lead by what you have told us!! But now it seems your telling us the opposite!! lol!!​

 

[martinh287]

I am not questioning what you may or may not know. It is your electrical system and you are monitoring the system.and like I said if it is working fine with 30mA protection you have no need to change it and i agreed it is offering more protection then what is needed so all the more reason to leave it in.

however thqt does not take away from the fact that I am surprised that a 30mA will nuisance trip with 4 computers attached but not trip with a welder.

 

[44ALLAN]

Before you start throwing your rattle out of the Pram, perhaps you should Remember what you have previously posted on this thread!! (post #14)

As a reminder....

We can only be lead by what you have told us!! But now it seems your telling us the opposite!! lol!!​

Hahahaha yeah rite.
Maybe just once you should get a SOH lol
Notice the eh!! after saying they were stuck?
That was my response to your condescending earlier post.

'Something like a fail safe system them!! lol!! Not a very well planned/designed installation having a EL protection at the front end, with nothing downstream to discriminate with. Can be more trouble than they are worth in most cases!! lol!!'

​

That was me saying to you don't treat me like a thicko please.
Might be shot and not very well planned indeed.......................don't patronise it doesn't suit you mate.

 

[44ALLAN]

I am not questioning what you may or may not know. It is your electrical system and you are monitoring the system.and like I said if it is working fine with 30mA protection you have no need to change it and i agreed it is offering more protection then what is needed so all the more reason to leave it in.

however thqt does not take away from the fact that I am surprised that a 30mA will nuisance trip with 4 computers attached but not trip with a welder.

Again........what can I say.
I know you are not questioning my post mate but if they don't nuisance trip and they test ok like we've both said why change it?

 

[Engineer54]

Hahahaha yeah rite.
Maybe just once you should get a SOH lol
Notice the eh!! after saying they were stuck?
That was my response to your condescending earlier post.

'Something like a fail safe system them!! lol!! Not a very well planned/designed installation having a EL protection at the front end, with nothing downstream to discriminate with. Can be more trouble than they are worth in most cases!! lol!!' A perfectly reasonable assessment, so what's wrong with it??

​

That was me saying to you don't treat me like a thicko please.
Might be shot and not very well planned indeed.......................don't patronise it doesn't suit you mate.

I've no intention of patronising a thicko!! lol!!

(And that was me, answering your condescending posts with my SOH!! lol!!!!)

 

[44ALLAN]

I've no intention of patronising a thicko!! lol!!

(And that was me, answering your condescending posts with my SOH!! lol!!!!)

ok keyboard hero..............'A perfectly reasonable assessment,so what's wrong with it??'.
You say it's not very well planned so give me your opinion on one of my 3 phase boards that has EL protection at the front end if you would be so kind
It became surplus to requirements but just happened to be installed next to the site of the new canteen.
So I ran a Swa single phase cable to a C/unit which now feeds canteen lights/canteen heater and 3 double sockets for fridge/microwave/kettle.
If the Rcd in the board trips I lose all that lol...............bit like losing one half of your house when an Rcd trips really lmao.
Making a statement saying it isn't very well planned without knowing the circuits installed says it all really.
Seems like all these houses are the same with split rcd's..........not well planned if you lose upstairs lights and downstairs sockets etc........or is that ok by you

 

[Engineer54]

Get back in the pram with your rattle man!! ....Jesus!!

 

[44ALLAN]

Thought not

 

[Engineer54]

It became surplus to requirements but just happened to be installed next to the site of the new canteen.
So I ran a Swa single phase cable to a C/unit which now feeds canteen lights/canteen heater and 3 double sockets for fridge/microwave/kettle.
If the Rcd in the board trips I lose all that lol..

​

So for the sole reason that this existing 3 phase DB being convenient but with 30mA front end RCD protection you ran a a supply to a Canteen CU which i'll assume also has RCD protection. Not exactly the ideal installation design is it?? Don't suppose it entered your mind any, to modify the 3 Phase DB to make it more usable/suitable for the Canteen as well as any future installations did it!!

So what are you trying to convince us on here, that your efforts conform with previous and outdated editions of BS7671 so it must be OK to do the same now?? It says a lot, that you actually KNOW, that the installation you have installed isn't really suitable, but went ahead anyway. Now your trying to defend your design with a load of irrelevant nonsense!! Why you would want to RCD a working industrial Canteen's lighting circuits is beyond me, unless of course you've wired them and the switch drops in T&E!!

BTW, I'm no a lover of dual 17th ed CU's they are a cheap compromise in my opinion and have never actually installed them on any of my projects!! There is also a big difference between a domestic installation and that of a commercial/industrial installation!!

 

[MDJ]

Didn't say DB's Don't come in this configuration, i said that i've never seen one!! lol!! Must be tiny welder if a 30mA RCD holds in, either that or it's shot!! I wouldn't have had a welder on an RCD in the first place, especially a 30mA unit lol!!

too true, it must be a soldering Iron lmao

 

[44ALLAN]

So for the sole reason that this existing 3 phase DB being convenient but with 30mA front end RCD protection you ran a a supply to a Canteen CU which i'll assume also has RCD protection. Not exactly the ideal installation design is it?? Don't suppose it entered your mind any, to modify the 3 Phase DB to make it more usable/suitable for the Canteen as well as any future installations did it!!

So what are you trying to convince us on here, that your efforts conform with previous and outdated editions of BS7671 so it must be OK to do the same now?? It says a lot, that you actually KNOW, that the installation you have installed isn't really suitable, but went ahead anyway. Now your trying to defend your design with a load of irrelevant nonsense!! Why you would want to RCD a working industrial Canteen's lighting circuits is beyond me, unless of course you've wired them and the switch drops in T&E!!

BTW, I'm no a lover of dual 17th ed CU's they are a cheap compromise in my opinion and have never actually installed them on any of my projects!! There is also a big difference between a domestic installation and that of a commercial/industrial installation!!

Nope... no RCD in the C/unit......open your mouth just a touch wider and you'll get your other foot in mate

 

[44ALLAN]

too true, it must be a soldering Iron lmao

Heliarc 306 TIG welder.
415/240v stick set.
Oerlicon MXW 400 Mig welder.

All covered by a 30mA Rcd and never tripped once in god knows how many years...........maybe I'll have a quiet word with the RCD's and tell them their supposed to trip eh !!

 

[MDJ]

maybe I'll have a quiet word with the RCD's and tell them their supposed to trip eh !!

You would be talking to yourself then Allen haha