MCB as a Main Switch in Garage Panel?

[jowjow]

Hello and thanks for checking this out.

I have a garage with its own consumer unit and at this point I'm trying to get some feedback on the pros and cons whether its best to install a "double pole mcb" or "main switch" in the garage panel before going to the individual mcb's.

so whats your opinions?

(I have seen similar installations and they seen to prefer one or the other)


Thanks

 

[littlespark]

There should some form of OCPD at the house end to protect the cable, so a mainswitch as isolator at board, with mcb to final circuits. (Rcd’s where required, of course)

 

[James]

Either is fine, normally depends on what the wholesaler has in stock at the time.

 

[jowjow]

Either is fine, normally depends on what the wholesaler has in stock at the time.

thanks for the message, do you think that using a double pole mcb for the garage panel would be an added layer of safety?

 

[jowjow]

There should some form of OCPD at the house end to protect the cable, so a mainswitch as isolator at board, with mcb to final circuits. (Rcd’s where required, of course)

thanks for your message. yes indeed it will include all the things you mentioned as well as surge protection. at board

 

[telectrix]

for a garage installation, it's usual to fit a mini CU ..2 pole main switch and 2 - 3 MCBs as required. the 2 pole main switch allows you to isolate both live conductors in case of a fault.

 

[GBDamo]

An MCB as a main switch, if that is what you're suggesting, is pretty pointless.

In the event of a small overload the circuit MCB will operate and in the event of a high current overload its pretty much Russian roulette as to whether the double pole will trip before the circuit MCB or even the MCB back in the house or all three.

I Can't see what it offers other than a third layer of fail safe for high current faults.

If you had one in your possession that was suitable I can't see what harm it would do though.

 

[jowjow]

An MCB as a main switch, if that is what you're suggesting, is pretty pointless.

In the event of a small overload the circuit MCB will operate and in the event of a high current overload its pretty much Russian roulette as to whether the double pole will trip before the circuit MCB or even the MCB back in the house or all three.

I Can't see what it offers other than a third layer of fail safe for high current faults.

If you had one in your possession that was suitable I can't see what harm it would do though.

thanks for the details.

the home panel will have a "main switch" and then an "rcd"- then to the garage panel.

the garage panel will then have another "main switch" or "double pole mcb" followed by the individual mcbs.

so if at the garage panel an mcb is installed instead of the main switch there will be 2 layers of fail safe. in view of this do you think it would be a good idea to have the double pole mcb at the garage?thx

 

[GBDamo]

thanks for the details.

the home panel will have a "main switch" and then an "rcd"- then to the garage panel.

the garage panel will then have another "main switch" or "double pole mcb" followed by the individual mcbs.

so if at the garage panel an mcb is installed instead of the main switch there will be 2 layers of fail safe. in view of this do you think it would be a good idea to have the double pole mcb at the garage?thx

No offense but I think your out of your depth. What your planning really needs more understanding than you have.

Get a spark in, for your own safety.

 

[Grant1987]

No offense but I think your out of your depth. What your planning really needs more understanding than you have.

Get a spark in, for your own safety.

Spot on, you’re trying to talk technical but without the foundation’s get a sparky in mate

 

[jowjow]

No offense but I think your out of your depth. What your planning really needs more understanding than you have.

Get a spark in, for your own safety.

no offense taken. I do this professionally and have the relevant qualifications, more than the average spark I would say. however I can understand that some of my terms might not be accurate because I'm not a native english speaker and we call things differently.

the setup i explained is used by 99% of professionals in my country, so im not reinventing the wheel or anything.

my questions was actually simple...."for a secondary panel such as in a garage, why some professionals use a main switch/isolator and others a double pole mcb, almost interchangeably. Obviously both will work and they can both be used according to code...but i kind of wanted to hear more opinions.

(Obliviously I am aware of the difference, one being manually operated and the other not and having over current protection etc)


Anyways thanks for your trying to help...


Note that I'm only asking questions, I can't ask this question to a local spark, a collegue or anyone because I would only get his personal opinion which might or might not be the best. Asking in a forum filled with (presumably) many capable and experienced professionally is the way to go (or probably not given the answers I'm getting.....)

 

[jowjow]

Spot on, you’re trying to talk technical but without the foundation’s get a sparky in mate

thanks for your mesage, are you a spark? if you are maybe you could at least attempt to answer my question because it should be easy.... thanks

 

[Grant1987]

thanks for your mesage, are you a spark? if you are maybe you could at least attempt to answer my question because it should be easy.... thanks

Well it needs more detail like the CSA of supply cable to garage consumer? Type of cable? The route of cable? You say it’s rcd protected so do you mean it’s fed via an mcb which is in turn protected via rcd providing additional protection For multiple circuits? I would personally use an rcbo at existing consumer unit and then use double pole main switch at garage with rcbos on that consumer although nuisance tripping is a factor but Aslong as you have rcbo at house consumer it won’t interrupt the circuits at house

 

[Grant1987]

Well it needs more detail like the CSA of supply cable to garage consumer? Type of cable? The route of cable? You say it’s rcd protected so do you mean it’s fed via an mcb which is in turn protected via rcd providing additional protection For multiple circuits? I would personally use an rcbo at existing consumer unit and then use double pole main switch at garage with rcbos on that consumer although nuisance tripping is a factor but Aslong as you have rcbo at house consumer it won’t interrupt the circuits at house

Also yes I am a spark are you?

 

[jowjow]

Well it needs more detail like the CSA of supply cable to garage consumer? Type of cable? The route of cable? You say it’s rcd protected so do you mean it’s fed via an mcb which is in turn protected via rcd providing additional protection For multiple circuits? I would personally use an rcbo at existing consumer unit and then use double pole main switch at garage with rcbos on that consumer although nuisance tripping is a factor but Aslong as you have rcbo at house consumer it won’t interrupt the circuits at house

thanks for the reply and details. the wire to garage will be a 4mm wire in a pvc pipe (more than enough given the relatively short distance)

You say it’s rcd protected so do you mean it’s fed via an mcb which is in turn protected via rcd providing additional protection For multiple circuits?

almost like you said but theirs no mcb (by design) at that point. basically the flow is like below:

Utility Company Meter(Which some type of overcurrent protection too) -> Main Switch A -> Surge Protector-> Over/Under Voltage Relay/Protector -> RCD (with time delay for discrimination) -> ---------Wire to Garage Panel------------> Main Switch B -> RCD -> individual mcbs

The above is a standard setup in my country so I'm not trying to reinvent the wheel.

So as not to get out of topic, my question with reference to the above was:

"Main Switch A" and "Main Switch B" - I have seen many(the majority) installations using a DP MCB instead of a Manual Main Switch/isolator, especially for "Main Switch B"

Also, some local shops dont even stock them in all brands and would tell you to get a DP MCB instead. And obviously I'm not very keen in opting for something just because the shop happen to have only that one...

Also, just because many local electricians do that does not mean that its the best way.

Personally (and I stand to be corrected) I think the ideal setup would be like this:

Utility Company Meter(Which some type of overcurrent protection too) -> Main Switch A -> Surge Protector-> Over/Under Voltage Relay/Protector -> RCD (with time delay for discrimination) -> ---------Wire to Garage Panel------------> DP MCB -> RCD -> individual mcbs

Notes:

Main Switch A - a manual isolator is a must here because its the only sure way that the power can be switched off (a DP MCB could malfunction given that it has more components)

DP MCB - an added layer of safety for overcurrent here, because one could always used the "Main Switch A" to be 100% sure that electricity is off.

any insight would be greatly appreciated, thanks