Do I need an RCBO for my generator?

salad17 · 13-04-2021 12:33am #1

I just purchased the Honda EU22i generator to power my coffee bar set up.

It will power the following:
Coffee machine: 300W (combi so the main power is gas)
Grinder 300W
Burco boiler: 300W
Water pump: 30W
Fridge: 120W
And possible some low power LED lights.

So total just over 1000W. At home I would just plug these into an extension with 4 sockets, so is there any reason I need some sort of breaker to protect these? Or is the fuse in the plug enough?

Clearly I don't know a lot about electricity, I'm just double checking because I sometimes see them used in campers etc.

Thanks!

13-04-2021 3:04am

RCBO: Yes

People not using circuit breakers in campers are doing it wrong and possibly weaponising their shells.

Pete67 · 13-04-2021 6:18pm

Maybe check the Burco rating - 300W seems very low for a water heater.

13-04-2021 6:30pm

salad17 wrote: »

So total just over 1000W.

As above I would expect the Burco to be at least 3000W.

At home I would just plug these into an extension with 4 sockets, so is there any reason I need some sort of breaker to protect these? Or is the fuse in the plug enough?

That depends. For a start, what is the output of the generator?

Clearly I don't know a lot about electricity, I'm just double checking because I sometimes see them used in campers etc.

..and you may get seriously hurt so I would strongly suggest that you get a qualified electrican to assist

13-04-2021 6:34pm

2011 wrote: »

That depends. For a start, what is the output of the generator?

Really? Because regulation or good practice?
Most generators I know can deliver 30mA across the heart.

I'm the only person I know that TN-S and RCD protects inverters. Cowboys father.

13-04-2021 7:03pm

Sir Liamalot wrote: »

Most generators I know can deliver 30mA across the heart.

I’m confused by your post.
What current can the generators you deal with deliver across a load?

13-04-2021 7:40pm

Anything between 300VA and 200kVA. Single and/or three-phase.

I don't understand how a generator might need a circuit breaker. As far as I'm concerned all unmonitored low voltage systems require an earth leakage circuit breaker because there's none that can't be lethal in the right fault condition.

I don't particularly think 110V CTE is a great solution either as anyone holding live opposing legs in either hand will tell you.

13-04-2021 8:32pm

Sir Liamalot wrote: »

Anything between 300VA and 200kVA. Single and/or three-phase.

That is about what I thought.

I think there is a typo in your earlier post, it threw me.
I think it should read:

Most generators I know can deliver more than 30mA across the heart.

I don't understand how a generator might need a circuit breaker. As far as I'm concerned all unmonitored low voltage systems require an earth leakage circuit breaker because there's none that can't be lethal in the right fault condition.

Unless it is small enough that it can't pose a risk

Also a fuse can often replace a circuit breaker (and can have a number of advantages too).
I would think that units have already been mixed up in this thread, so generator size may be worth checking

When selecting any type of protective device is good to know what the generator can deliver.

I don't particularly think 110V CTE is a great solution either as anyone holding live opposing legs in either hand will tell you.

Not really sure where this came from

13-04-2021 8:45pm

2011 wrote: »

That is about what I thought.

I think there is a typo in your earlier post, it threw me.

I do that a lot. I tend to write the entirely wrong word instead of simply misspelling one.

2011 wrote: »

Unless it is small enough that it can't pose a risk

like less than 30mA @ 230Vac?

2011 wrote: »

When selecting any type of protective device is good to know what the generator can deliver.

Yurp a lottov small inverters & gensets can't trip an MCB.
I was more recommending an RCBO for the earth leakage protection properties

2011 wrote: »

Not really sure where this came from

People don't put circuit breakers on site safety transformers. Fine in theory but you can easily get an operational high impedance L-E or N-E fault and then it's only a matter of time before someone gets hurt when the other leg fails.

It's one of those good enough for regulation isn't good enough for me situations.

A lottov lads run floating site gensets with no fault monitoring. I don't think that's acceptable.

Bruthal. · 13-04-2021 8:59pm

Sir Liamalot wrote: »

People don't put circuit breakers on site safety transformers. Fine in theory but you can easily get an operational high impedance L-E or N-E fault and then it's only a matter of time before someone gets hurt when the other leg fails.

Any example of this, in theory maybe?

13-04-2021 9:50pm

Class I circular saw, internal creepage fault between N-E due to moisture ingress & contaminants user nicks the flex with the blade making a L-E fault and becomes a potential divider on the L-N leg through the body of the saw.

You can get CTE inverters or so-called CTE inverters that are actually transformerless. Typically most "plug and play" cheapies are this flavour except it's 115V between L-E, & N-E...which can still hurt a lot.

It's not that I have a massive hang-up about 60VAC zaps nor 115V for that matter it's when a catering trailer rocks up onsite after doing 500 hard miles across-country with all the ban-maries and burcos and hobs flying around the internals of the trailer with a PAT test sticker from 2015 and they plug into a floating genset and assume it's perfectly kosher because nothing tripped that gets me.

Bruthal. · 14-04-2021 7:09am

Sir Liamalot wrote: »

Class I circular saw, internal creepage fault between N-E due to moisture ingress & contaminants user nicks the flex with the blade making a L-E fault and becomes a potential divider on the L-N leg through the body of the saw.

L-N leg a typo?
Anyway, I can't see that would make much difference to the potential between each pole and E in terms of increasing voltage.

On a side note, an RCD wouldn't trip with any user contact with cte setup on 110v. Although it would with earth faults above the 30ma.

14-04-2021 7:15am

Sir Liamalot wrote: »

Class I circular saw, internal creepage fault between N-E due to moisture ingress & contaminants

It’s not really a neutral though is it? As it’s a center tapped transformer, therefore dual phase.

If one phase has a fault to earth the saw will have under voltage (less than 110V).
I would expect the user to notice that the saw won’t work properly immediately.
Let’s suppose they don’t.

Whether this is caused by moisture or contaminants or other is not relevant.
I wouldn't see too many class 1 circular saws either. Sure they exist, but not normally seen on site.

user nicks the flex with the blade making a L-E fault and becomes a potential divider on the L-N leg through the body of the saw.

So a multiple fault scenario, always less likely than a single fault but sure it is possible. I would expect that the resistance between the blade and the user to be pretty poor. Now a voltage that has been even reduced further is applied across the user (due to the voltage dividers that you mention). Not ideal, but it could be worse.

BTW: I normally see DP breakers on site transformers.

Bruthal. · 14-04-2021 1:20pm

There wouldnt really be any voltage applied to the user. Any earthed item they are holding will still be at 0v. The example given is moisture between 1 pole and centre tap earth. The loading of the saw itself is across the winding with cevtre tap held at 0v. If we add a 55v bulb between 1 pole and earth tap, that will have no effect on the centre tap potential anymore than the saw load would.

14-04-2021 1:27pm

Bruthal. wrote: »

There wouldnt really be any voltage applied to the user. Any earthed item they are holding will still be at 0v. The example given is moisture between 1 pole and centre tap earth. The loading of the saw itself is across the winding with cevtre tap held at 0v. If we add a 55v bulb between 1 pole and earth tap, that will have no effect on the centre tap potential anymore than the saw load would.

This is true. I think we would need a further failure or two before the user would get a shock.

14-04-2021 5:38pm

I probably learn more from you two correcting me than any other source.

I think if there's a fault it ought to trip.
I see a lottov floating installations (boats & sites) where it's quite possible the hardware is operating with an unflagged fault and can be so for years undetected...the second fault is a matter of time.

iwillhtfu · 14-04-2021 5:50pm

That certainly turned into some willy waving.

OP, If a permanent set might be best to have an electrician wire the outlets to a small consumer unit. In some cases depending on the generator they will have built in RCBOs and small power MCBs.

I assume this is going into the latest fit of coffee based horse boxes.

As mentioned your burco load doesn't seem right.

14-04-2021 6:36pm

iwillhtfu wrote: »

That certainly turned into some willy waving.

:rolleyes: I suggest you read it again if you thinks so.

Granted SST warranting RCDs is a stretch because

fcp,small,wall_texture,product,750x1000.jpg

fcp,small,wall_texture,product,750x1000.jpg

that doesn't make it wrong, unnecessary or unsafe.

Do you think a 5kVA 230Vac generator requires a "circuit breaker"?
Do you think a 230Vac Class I trailer/vehicle of 5kVA design load requires a "circuit breaker"?
Do you think both 230Vac 5kVA generator and 230Vac Class I mobile installation require a "circuit breaker"?

14-04-2021 6:48pm

Sir Liamalot wrote: »

I probably learn more from you two correcting me than any other source.

I think if there's a fault it ought to trip.

Not always.
Sometimes we require a level of fault tolerance.

I see a lottov floating installations (boats & sites) where it's quite possible the hardware is operating with an unflagged fault and can be so for years undetected...the second fault is a matter of time.

This is why we often use devices to monitor the insulation resistance with marine installations.

iwillhtfu · 14-04-2021 6:51pm

Sir Liamalot wrote: »

:rolleyes: I suggest you read it again if you thinks so.

Granted SST warranting RCDs is a stretch because

that doesn't make it wrong, unnecessary or unsafe.

Do you think a 5kVA 230Vac generator requires a "circuit breaker"?
Do you think a 230Vac Class I trailer/vehicle of 5kVA design load requires a "circuit breaker"?
Do you think both 230Vac 5kVA generator and 230Vac Class I mobile installation require a "circuit breaker"?

Do you honestly think I'm about to start playing your childish game. :rolleyes:

Provide the information requested by the OP save your opinions for a general chat thread.

14-04-2021 6:53pm

2011 wrote: »

Not always.

True. Submarines, ships, aircraft etc...let 'er buck

2011 wrote: »

This is why we often use devices to monitor the insulation resistance with marine installations.

Exactly, this was implied when I stated an unmonitored installation requires a breaker.

Leisure marine lads lift the earth to "save the zincs".

I see more that way than not.

salad17 · 15-04-2021 12:42am

iwillhtfu wrote: »

That certainly turned into some willy waving.

OP, If a permanent set might be best to have an electrician wire the outlets to a small consumer unit. In some cases depending on the generator they will have built in RCBOs and small power MCBs.

I assume this is going into the latest fit of coffee based horse boxes.

As mentioned your burco load doesn't seem right.

Wow that went a bit mad and ye lost me!

The generator is the Honda EU22i which is 2200Watts peak output.

I don't know what has happened with these horse boxes, it's mad! This coffee shop is going into my existing business which is a kayak and watersports centre and has been in the works for 2 years but I'm just implementing it now.

You're right about the (not yet purchased) burco, it's 1000W, not sure how I made that mistake! I'm going to switch to a gas burco instead as I can't facilitate that power.

salad17 · 15-04-2021 12:48am

2011 wrote: »

..and you may get seriously hurt so I would strongly suggest that you get a qualified electrican to assist

But surely you don't need to get an electrician every time you plug something into a generator? It's a regular 3 pin plug?

If I bought it and plugged a light in I shouldn't need an electrician, at one point does it become dangerous because I'm drawing more power, and what determines when it's safe and when it needs an MCB? (Genuine questions, not meant to be as sarcastic as they sound when I re read them!)

And if you do always need an MCB to be wired in when using a generator, surely it shouldn't just be ready to use when you buy it with a standard socket there, I mean any consumer I know who's used a small household generator would never even think to question it.

15-04-2021 12:51am

Nice machine...quiet too by standards. I heart the way they spec genset noise in dB from 7 meters away. The standard reference is 1m away.
I've a 4kVA I built battery-Inverter set that's 35dB right beside it Mwahaha.

She's got an onboard overload trip. I would ensure it's neutralised, add an RCD and earth electrode as close to the genset as possible.

salad17 · 16-04-2021 7:48pm

Sir Liamalot wrote: »

Nice machine...quiet too by standards. I heart the way they spec genset noise in dB from 7 meters away. The standard reference is 1m away.
I've a 4kVA I built battery-Inverter set that's 35dB right beside it Mwahaha.

She's got an onboard overload trip. I would ensure it's neutralised, add an RCD and earth electrode as close to the genset as possible.

Thanks, yeah it is, though not as quiet as I was expecting from all the rave reviews!

How did you build it?

So is it always expected that you add an RCD to a generator and never plug anything directly into it?

16-04-2021 10:14pm

salad17 wrote: »

Thanks, yeah it is, though not as quiet as I was expecting from all the rave reviews!

Loud generators are 120dB at 7m

salad17 wrote: »

How did you build it?

2 years R&D (one of which it sat on a shelf). Silly amounts of money and invested time. But hey there's nothing else like it.
4kVA 2.5kWh, solar ready, genstart & throughput automated, 35dB, grid tie-able, synchronising up to 12kVA, 1 hour recharge.

Big one on the right outtov it's case.

She's sporting her third €2.5k inverter-charger now. I tend to run them at 100% duty until they break or pass before I enter them to service. Most break, derate or don't meet spec.

salad17 wrote: »

So is it always expected that you add an RCD to a generator and never plug anything directly into it?

If you want to have an acceptable level of life harm (electrocution) protection yes it is. Most "lads" rather not bother because it's more convenient or they don't understand it.

Do I need an RCBO for my generator?

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