The usual shed installation question

[Roo]

I am fully aware of Part P.

This installation WILL be checked by a registered spark and issued a certificate if all correct (long story don't really want to post reasons on the internet) and no it's not just me saying that.

I have a friend who has a wooden shed.......

Came up with the following design and would like some scrutiny please as I know there are a lot of good sparks that use this forum.

Shower is an 8.5 kw (forgot to put in diagram).

Some things I don't know.

The SWA run is around 6meters mostly clipped to the house with around a meter underground, is this allowed or does it need to be buried all the way?

With the run being 6meters will I need a switched fuse after the henleys?

I'm also emailing the design to the spark that will be testing but would just like some other opinions.

Also excuse the diagram I'm no mspaint expert

Thanks
View media item 3873

 

[Spark123]

A shower in a shed? New one by me!
Yep, you'll need a fused switch in the henleys. The SWA can run underground, above ground etc as long as it is installed correctly i.e. secured.
How are the lights etc in the shed wired? Will need to be on an RCD (RCBO?) if in the shower rm.
Do you also need a fan?
Any extraneous conductive parts?

 

[RF Lighting]

That was my only concern.

You would need an RCD if any of the circuits are in the shower room, or if any of the wiring is concealed within a wall.

I haven't done a VD calculation to check cable sizes, but you need to ensure you have a 10.0mm² earth to the shed to bond the water supply and any other extraneous parts which may be present with a 10.0mm² cable at their point of entry to the building.

You haven't shown a local DP isolator for the shower. I assume this is an oversight rather than a deliberate omission.

 

[Roo]

Yup shower in a shed

The shower will be used to rinse pets over a bath (similar to a hairdressers).

Did think about a fan but the shed is quite big, would have though the door would be open when the shower was in use and it does have a large window to vent so didn't think I'd need one.

Everything including the light will be on the RCD was thinking of leaving the light off but then he said shower so had to up the SWA and thought it would be a good idea to put everything on the RCD.

So a 60A fused switch after henleys will be ok?

 

[Roo]

RF..

Correct I did forget to draw an Isolator even after looking for a good price for one just now.

 

[DESL]

60A switch fuse would protect feed to shed as you drawing shows no CPD.

I'd use a metal clad switch fuse as it'd be a good to terminate SWA, tails from Henley block grommeted .

How long is SWA ?

Do pets come within scope of livestock?

 

[flyingsparks]

In case you dont already know, you will need to run 25mm tails from the henleys to the switch fuse, presuming its a 100A supply.

 

[Roo]

Got a feeling it'll be a 80 but I'll be giving him some 25mm anyway.
I'm ok with that bit

 

[Roo]

Do pets count as livestock?

If they do is there anything else I have to do before the spark comes to test?

DESL: It's around a 6metre SWA run.

Is metal clad a must with SWA or can I still use a plastic enclosure?

Do I need to terminate the armour or can I just leave that as mechanical protection and stay with the 3rd core as my earth?

I take it I'm gonna have to use a gland into the CU and this would have to be earthed incase it were to come into contact with a live in some way?

If so I'll stick with the metal enclosure as DESL suggested.

Sorry for the basic of questions for you fella's but I don't work with SWA in my job so never had to terminate it.

I'm confident with the CU onwards and obviously the mains but first time using SWA.

I'm also thinking that if a plastic water inlet was used I wouldn't need to/couldn't bond am I correct?

If theres any changes to my design you may think might help i'd be very grateful.

The spark testing will (I hope) pick up on anything I've missed but i'd just like to do it right first time so I didn't mess him about.

 

[ColJack]

Do pets count as livestock?

no they don't, otherwise every house would have to comply with the relavent regs, you've no way of knowing if the owners will have pets when doing initial wire..

Is metal clad a must with SWA or can I still use a plastic enclosure?

you need some way of securely terminating the SWA.. and metal would be best.

Do I need to terminate the armour or can I just leave that as mechanical protection and stay with the 3rd core as my earth?

yes it needs to be an EARTHED metalic sheath..

I take it I'm gonna have to use a gland into the CU and this would have to be earthed incase it were to come into contact with a live in some way?

yes you need a proper gland on the armour at both ends..

if you're running water to the shed anyway, then it'll be best to bury it and lag it to keep from freezing in the winter..

 

[Pensdown]

Do pets count as livestock?

Thankfully, not in the context of your project.

Having wired a doggie shower in a kennel complex, I would suggest that you extend the zone 1 regs for an extra few metres. When dogs get out of the shower they don't dry themselves with towels like we do - they have a good shake and the water goes everywhere!

 

[Roo]

Coljack: thanks, should I be looking at a metal CU to then to make it easier?

Pensdown: Thanks also I'll have that in mind, I let Mrs Roo wash ours

Just to start a debate....

Which make of CU do people prefer?

Was looking at a crabtree but I've been having to tighten a lot of their isolators up lately which have been fitted by a housing asso around here and all their sparks can't be weak wristed.

And should I be using RCBO's instead of the seperate RCD?

 

[lazygit]

I'm also thinking that if a plastic water inlet was used I wouldn't need to/couldn't bond am I correct?

If its a TN-C-S system you shouldnt export the earth to the shed if there are extraneous parts (metalwork that offers earth potential).

Instead you should put an earth rod in, and make the shed TT

 

[Spark123]

Where there are extraneous conductive parts in the outbuilding, converting it to TT is one option. Connecting the extraneous cp back to the MET using the correct size main protective bond (table 54.8 + verify with DNO) is another option, unless it has changed under the 17th ed? 16th ed regs wiring matters

 

[Roo]

Quick update with a few questions.

This is what I sent to the spark testing which he agreed.
View media item 4031
Started it tonight after work and have a few questions.

I'm using a wylex 5 way metal clad CU which comes with a main switch.
Are there any regs that say I need to use this too or can I get away with just using the RCD?
The only reason I'm asking is although I could fit the lot in the CU it only has a bottom rail for the main switch and I feel if I didn't use the Main switch but put the RCD there instead the MCB's would be a lot sturdier as these are only held by the busbar and top rail.

The wholesalers also didn't have a 45A mcb so I ordered a 50 as I calculated a 8.5 kw shower was around 37A at 230v(tell me if I'm wrong as I don't really need to use my brains that much in my job), I've obviously upped the shower Isolator to a 50A too.
Should I still have gone for a 40A?

Am I also ok to clip the cable direct on my runs or should I use trunking?

The thought crossed my mind that with the shed having animals in it which like to chew trunking may be better.

Sorry for the basic questions but as I said earlier I don't want to mess the spark around thats coming to test.