Bathroom wiring questions

If the motors have an earth connection in their flex, then they are class I. (generally if its metal cased and not marked as class II then its best to assume class I)

So long as the earth of the circuit feeding the motors is included in the rooms EQ bonding, then you don't need anything else. The protective conductor feeding the motor itself will serve dual purpose as both earth and bonding connection.

Its likely its an induction motor, and will have a high inrush current. Hence the need for a higher rating of fuse than nominal[1] 10A that the

2.1kW rating would suggest.

It might be worth tracking down the manual for the motor if you can to see if it actually specifies that the motor *must* have additional protection from a 16A device, or whether it is just highlighting that protection with a 13A fuse in a SFCU etc unlikely to hack it due to the high inrush.

If it specifies that it must be protected at 16A device, then it will make your task a little more interesting if you want to feed it from a spur on a 32A ring circuit. You would then probably have to use a MCB, or a HRC cartridge fuse in a suitable enclosure instead.

[1] Induction motors also tend to have non unity power factors, which can increase the actual maximum current drawn.
Reply to
John Rumm
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I am sure Lee will ask if he is unsure.

Reply to
John Rumm

Just get the cheap electric tooth brushes which use standard batteries. You'll thank me when the batteries in the uber expensive rechargeable toothbrushes die 5 minutes after the warranty is up.

Reply to
philipuk

+1

I use the cheapest Oral B. About ten quid from Amazon with replaceable batteries. The brushing action is identical to many of the more expensive rechargeable models. At that price it's no great problem to replace them when they eventually die after a few years of use, usually due to the switch failing.

Instead of using Duracells I use rechargeable 2300mAh AA's which give me about 2 weeks between charges and are still recharging without problems after several years use.

Reply to
Mike Clarke

Thanks John.

There is no other bonding in the bathroom as all plumbing is plastic as it the bath.

Rather than a spur, I was going to break into ring on that floor and extend it to the bathroom. It is a bit of a pain as there isn't a straight forwa rd way (that I can think of) to do it other than go to the nearest socket ( bedroom across the landing) and split it there. Rather than have a junction box I was going to add an extra socket besides it to take feed back from t he bathroom to rejoin the ring (if you see what I mean).

Will try and track down the installation manual for the bath and revert.

thanks again

Lee.

Reply to
leenowell

nd it to the bathroom. It is a bit of a pain as there isn't a straight for ward way (that I can think of) to do it other than go to the nearest socket (bedroom across the landing) and split it there. Rather than have a juncti on box I was going to add an extra socket besides it to take feed back from the bathroom to rejoin the ring (if you see what I mean).

OK - I have managed to find an installation manual online but the electrica l piece seems generic across the Duravit range. It says the following...

Circuit Breaker - In = 16A RCCB I delta

Reply to
leenowell

The latest generation of Oral B products contain lithium ion batteries. Not before time - I never understood why I was paying a premium price for an appliance containing an obsolete battery.

Reply to
Scott

Profit

Reply to
Tjoepstil

Did that years ago. It didn't last long, the waterproof seal wasn't really waterproof.

ISTR there being youtube vids on how to open sealed Oral-Bs & replace the battery.

NT

Reply to
tabbypurr

If all the circuits that enter the room are protected with a 30mA trip RCD (and the house main EQ bonding is to spec) then you could take advantage of the 17th edition relaxation that allows EQ bonding to be omitted in these cases.

IME Its possible to use crimps or wago terminals in the back of a socket box to join into a ring if you want - so it can all be done at one double socket location.

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Having said that, you may be better off putting your additional switched protection adjacent to the socket and running a spur from that to the spa (there is no real advantage to the ring being extended to and from the spa)

(is it just a pump or a heater as well? 2+ kW seems like a bit much for just a pump)

Does your source circuit already include a RCD? (if so, no need for another if the trip threshold on the existing one is connect all pole disconnector mains switch upstream located out-side

Under a bath also counts as outside of the zones if you need a tool to access the space.

As I mentioned before, its the "16A version" that makes it more difficult since anything designed to be protected by a BS1361 fuse is not going to work in this situation if you read the manufacturers spec to the letter.

(the reality is a 13A fuse is probably more than adequate[1], but they are likely attempting to make their instructions applicable Europe wide where 16A circuits are common and UK style fusing close to appliances is not).

No, that seems a bit odd.

[1] Unless all that 2.1kW rally is just down to one big motor, where the inrush could take out a 13A fuse. (in which case a C10 MCB would probably be a good match)
Reply to
John Rumm

You could just run one cable as a spur off the back of the bedroom socket instead of extending the ring. Assuming that the back box is deep enough to accommodate the extra cable.

The fuse or breaker doesn't have to be at the start of the spur, it can be in the bathroom cupboard.

Reply to
Mike Clarke

Thanks both

The bath has 2 pumps and one includes a heater to keep the water warm during operation.

Reply to
leenowell

ing operation.

Hi All,

I have now heard back from Durait. Looks like 13amp will be fine thankfull y. So from the above, I think I can now use one of these for the bath

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and put it in the cupboards below the sinks. I seem to recall from above th at I needn't break the ring and just have this (and the 2 shaver sockets) a s a spur from a double socket in an adjacent room. Is it worth wiring the

2 shaver sockets off this RCB too or just have a junction box there (IP4x i n case) and wire all 3 off the feed?

Thanks again all

Lee.

Reply to
leenowell

Good, I had a feeling that might be the case.

Sorry if I missed it, but did you mention if the socket circuit already has RCD protection in the CU?

Well you could do either... however doing the former treats the whole installation as if you had a fused spur from the ring. Hence you can add any number of things downstream of the spur.

(Going with the second option means you are treating the feed from the circuit as an unfused spur, and hence would normally need to keep in mind the total load you could potentially place on the single spur cable. In this case however your ~2kW load plus to shaver sockets will be well below any load you would need to worry about)

Reply to
John Rumm

Thanks John

I checked the consumer unit. There is a bank of MCBs and then a RCCB then another bank and another RCCB. I assume the RCCB protects the bank of MCBs to the left of it. Is that correct? If so, the bank of MCBs to the left are...

2xB6 2xB16 2xB32 1xB40

The RCCB is 80A 30mA. 80a seems a bit odd given the total of the MCBs is much more. Unless it only protects the nearest 1 or 2 MCBs?

Thanks again for your help

Lee.

Reply to
leenowell

Thanks John

I checked the consumer unit. There is a bank of MCBs and then a RCCB then another bank and another RCCB. I assume the RCCB protects the bank of MCBs to the left of it. Is that correct? If so, the bank of MCBs to the left are...

2xB6 2xB16 2xB32 1xB40

The RCCB is 80A 30mA. 80a seems a bit odd given the total of the MCBs is much more. Unless it only protects the nearest 1 or 2 MCBs?

Thanks again for your help

Lee.

Reply to
leenowell

diversity

NT

Reply to
tabbypurr

That sounds like a typical 17th edition style split load CU, where you have all circuits protected by RCDs, but they are spread out over a pair of devices, so you maintain some discrimination. For example a layout like:

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Generally that seems to be the most common arrangement - although it does depend on the brand of CU. Some place the main switch or RCD on the left of the protected block of devices.

It sounds like that there are no non RCD protected circuits (as you might find with a so called "high integrity" CU with provision for some non protected circuits that can be fitted with MCBs or RCBOs:

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The implication of this is that you *do not* need any further RCD protection for the spa pumps / heaters.

No it will protect all of them. Finding that the maximum load on all circuits when summed is greater than the rating of some upstream device is not uncommon, but allowances can be made for diversity in the loads. More detail here:

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Reply to
John Rumm

Thanks very much John. Great explanation. Yes the picture us very similar t o my arrangement.

I was thinking... Adding the RCD although an extra £10 more than a swi tched fused spur I thought it would give extra protection so might as well do the RCD one. Am I fooling myself :)

Thanks again. Lee.

Reply to
leenowell

Probably...

One might argue in the relatively rare case of one of the RCDs failing (that manifests as a non trip in a situation where it should have), then having a second one will serve as a backup. For all other (more typical) situations it serves no real benefit.

(and should you get a trip for any reason, you potentially have devices to reset since you will get no discrimination between the cascaded devices)

Reply to
John Rumm

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