Type A Type B?

[Onoff]

This company sells recon circuit breakers:

Distribution & Circuit Protection

Distribution & Circuit Protection

www.reconelectrical.co.uk

I've had a few Crabtree C50s off them.

 

[EM1L4]

Yeah. I know that.
However.... on Gensets the RCD is a requirement where it's hire/temp sets where you can expect surface run cables and Distro - so higher risk of damage to connected cables and subsequent shock risk.

We supply sets that are connected to pumping stations with large industrial pump sets etc.... and it's common where the site runs happily off Utility (which isn't EL protected at source like the genset is) - but trips a genset RCD - so it being adjustable enables the genset to supply an essential load in an emergency situation.
Often you're not talking about a big change - raising it to say 150mA for 0.3s typically does the trick, and still provides good protection.
Note the site Distribution still retains its own Dis Board protections that it uses on Utility - really the only thing the genset RCD is covering is it's supply cable

Sounds like you know what your doing, your first post gave the wrong impression

I do a lot of generator supplies and they often have to run at 300-1000ma with time delay to supply a construction site with cabins, power, lighting and tower cranes etc and that's fine.

Out of interest what is creating hundreds of ma’s EL? From that list only the crane with a huge VFD??

 

[Memmeddu]

Type C for general purpose is fine .

 

[mtt.tr]

Type C for general purpose is fine .

That would depend on your circuit impedance

 

[rtcosic]

Thank you all. I will study the replies and try to understand the termonology.

Edit: Terminology even!

 

[dobbslc]

Sounds like you know what your doing, your first post gave the wrong impression


Out of interest what is creating hundreds of ma’s EL? From that list only the crane with a huge VFD??

Some sites have 2 cranes plus welfare set up's with 30 or more cabins, hoists and temp supplies to the lifts. I set the cranes up at 300ma minimum each and sometimes 500ma if they're "a bit trippy"
The lift installers think they're special and demand 500ma supplies for each lift! That can't be done without affecting the RCD discrimination all the way back the the mains so they get what we give them!
Most of the time it's one crane per generator though.

 

[Dave-sparks]

With regular MCB's I believe that type C or type D would be advised for large motor starts or other big current spikes (like a welder).
A & B sounds a bit sensitive for garage kit maybe?
The other thing is if there is actually an Earth Leakage issue with the kit - enough to trip the RCBO.
You could get an adjustable RCD unit piggy-backed to a 16A or 32A C or D rated MCB maybe? Then you could raise the EL disconnection current and time delay to "tune out" your tripping issue maybe.
Disclaimer: I'm not a Sparky, but working with Gensets a lot we do see quite a lot EL Trip issues

Am adjustable RCD, if set to anything other greater than 30mA and instantantaneous trip will not provide the appropriate protection against electric shock.

Variable RCDs should only be used by someone who knows what they are doing to provide appropriate discrimination where upstream RCDs are providing fault protection and downstream RCDs are providing protection against electric shock.

 

[Dave-sparks]

I've never heard of m2 I would guess it probably came by a local wholesaler so I would suggest call around local wholesalers.

Worse than that, M2 is the latest CEF own-brand as far as I know

 

[Dave-sparks]

Yeah. I know that.
However.... on Gensets the RCD is a requirement where it's hire/temp sets where you can expect surface run cables and Distro - so higher risk of damage to connected cables and subsequent shock risk.

RCDs are generally required on generators because they are incapable of delivering enough fault current to operate MCB's or fuses within the required disconnection time.

 

[Dave-sparks]

I do a lot of generator supplies and they often have to run at 300-1000ma with time delay to supply a construction site with cabins, power, lighting and tower cranes etc and that's fine.
Anything in a domestic dwelling needs to be 30ma max.

Anything in a domestic dwelling does not need to be 30mA max.

RCDs providing additional protection against electric shock should be 30mA or less with instantaneous trip in domestic or any other type of installation.

RCDs provided for fault protection can be greater than 30mA and have a time delay in domestic or any other type of installation.

 

[mtt.tr]

Worse than that, M2 is the latest CEF own-brand as far as I know

That means over priced crap

 

[dobbslc]

I'm trying to keep it simples for the OP!
I said any new circuit should be 30ma RCD protected in a domestic installation, as he was talking about installing a new ring that's what he would need, no time delays, no adjustable setting etc.

 

[mike os]

Given the first line of the op... call an electrician

 

[GRW]

RCDs are generally required on generators because they are incapable of delivering enough fault current to operate MCB's or fuses within the required disconnection time.

Actually I'd day that's old news and/or only applicable to small basic generators.
Modern industrial alternators (not shunt-excited) are capable and rated by the Mfr of 300% overload for 10s.
There is no requirement for an RCD on a permanent hard-wired generator - the RCD is there for protection of surface distro and possible hand tool use off any socket array.

 

[GRW]

Sounds like you know what your doing, your first post gave the wrong impression


Out of interest what is creating hundreds of ma’s EL? From that list only the crane with a huge VFD??

People cleverer than I have said that it's due to the Impedance of a generator being greater than that of a much larger utility supply.
Problems with voltage instability and then operating problems of VSD's and UPS is generally down to the amount of Total Harmonic Distortion (THD) on the Load (both as a proportion of the genset capacity and as a proportion of the Load). Basically the greater the THD, the exponentially higher the chance that the distortion results in VSD's not operating, and UPS's refusing to switch out of bypass and use the gen supply.
A lot of Water Co large pumps in Works have been changed to VSD of similar power - but the site backup genset is perhaps 25+year-old. The genny had no problems running the (higher start current) older SD pumps, but the VSD's didn't "like" the genset (something that had never occurred to them till it happened).
THD and current build-up on the Neutral as a result has also seen the N now required to be the same diameter core as the Lives (instead of 50%) on installs.

 

[Memmeddu]

That would depend on your circuit impedance

Difference between Class A, B, C, D, K and Z Type Miniature Circuit Breakers (MCB)

MCBs are classified into different types based on their tripping characteristics which are the range of tripping fault current at which the device operates in the event of a short circuit or overload. Type...

mechatrofice.com

 

[Dave-sparks]

That means over priced crap

It usually does, the only thing the M2 has going for it is double screw terminals for the tails in the top of the main switch. Unless I've confused them with someone else's glossy marketing.

 

[mtt.tr]

Difference between Class A, B, C, D, K and Z Type Miniature Circuit Breakers (MCB)

MCBs are classified into different types based on their tripping characteristics which are the range of tripping fault current at which the device operates in the event of a short circuit or overload. Type...

mechatrofice.com

If your impedance is to high you won't make the 0.4s because of the trip curve



Though arguably you probably won't make volt drop either

 

[mtt.tr]

It usually does, the only thing the M2 has going for it is double screw terminals for the tails in the top of the main switch. Unless I've confused them with someone else's glossy marketing.

That is a benefit,wish we did something like panels and have terminal block ahead of the isolator

 

[Dave-sparks]

That is a benefit,wish we did something like panels and have terminal block ahead of the isolator

What panels are you fitting?