Bathroom Junction Box

Bathroom Junction Box

1. Hello All, Just gutting and refitting the bathroom, part of which used to be the landing (long story, past owner). Was just doing first fit and found lots of cables under various parts of the floor - these range from ring main to lighting - they dont feed anything in the bathroom, just run under the floorboards.

   There will be electric appliances in the bathroom - downlighters which are IP65 fed from double insulated SELV transformers, a bathroom cabinet with built in light IP44) and a jacuzzi bath which is being installed by a sparky using RCCD etc, BUT i'm now worried about dangers of having that lot under the floor - should i be? is water dripping into a junction box going to cause a shock? especially on lighting cabling that may not be earthed i guess??

   Earthing is present from the consumer unit to the water and gas (6mm needs upgrading but its there), the consumer unit has one 80ma RCD covering all circuits (yes we get a trip every time a bulb goes!

   Thanks in advance

   Dean

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4. They are outside the bathroom (technically). However water ingress could cause a fault to occur.

   If you are worried consider replacing and / or re-routing the cables if possible, certainly replacing the lengths between points will remove the chances of water ingress into juc. boxes.

5. If they are typical screw terminal junction boxes then they shouldn't be under the floor where they will become inaccessible, therefore you should consider replacing and rerouting the offending lengths of cable to avoid using JBs, use crimps in an adaptable box, or use a maintenance free JB (but that opens another can of worms).

   All that aside, there is nothing to worry about, under the floor is not classed as being a part of the bathroom and it's very common for cables to be run there. Certainly, if there are no junction boxes or connections, there is no way for water ingress to cause a problem anyway - believe it or not, PVC cable is waterproof!

6. Thanks for the replies. i'm not worried about a fault developing, i could get access through utility room ceiling if absolutely nessesary (even if expensive) , i'm worried about someone getting electrocuted (kids splashing in the bath etc), suppose earthing & rcd would prevent this?

7. Neither can guarantee absolute protection, but both certainly help. As bathroom floors are usually waterproof, I'm not sure how water would be getting anywhere near the wiring anyway. If a leak were to develop and water managed to work its way into a JB under the floor, you would likely know about it before things got serious enough for people to be receiving electric shocks.

8. Dean, "Access" means easy access using normal tools. It should be possible for an electrical inspection (which includes a physical inspection of terminations) to be carried out without removal of building structure.

   I had a similar case during my first "Periodic Inspection & Test" at a particular rented cottage. Someone had fitted a new Distribution Board with new white-sheathed cables that disappeared into the ceiling above. The room above was a bathroom and after much floor board / bath panel removing, I found, just at finger tip reach, some chocolate block terminals wrapped in insulating tape where the cables joined the old grey sheathed ones. I declared the installation "un-inspectable" told the owner the bad news and went home. He didn't get a certificate.

9. The white cables were the first clue. Yuck!

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12. And presumably you didn't get paid, as you had not issued a periodic inspection report? ... theres a reason the report has only two outcomes; satisfactory, and unsatisfactory*, not un-inspectable , just mark such things down as a code three and move on and do as good a job as you can making sure you note the areas requireing further investigation... that way, you can get paid, and the homeowner can glance over the report once, sigh, and file it away never to be seen again...

    And satisfactory perioidics get issued rarely!, the exception are buildings which get done religiously every interval and in the event that something is needed, have it done, the rest are usually inspected because someone has told them they have got to, or advised them that it would be a very good, idea, etc, ect

13. My last house had the CU in a room right under the bathroom so all the cables went under the floor.

    Before Tiling I created water breaks & ensured that unless leaking from directly above it, the water could not get to the CU are of the ceiling below.

14. How? The RCD in your existing CU won't do, and you can't get RCBOs for it, I'm sure.If it isn't then that's a good sign that you should have the place rewired.

    And as you are gutting and refitting the bathroom now would be a good time to have it done.

    The RCD shouldn't trip, but if you've got Type 1 MCBs they are even twitchier than Type B's, so they'll go every time when a bulb blows.

    An 80mA RCD is not OK for any situations which now require one to be fitted.

    Time to replace the CU.

16. Back in the days when it wasn't grey for PVC and white for LSF, and either could be either colour.... round here, seeing white pvc T+E was a sign of DIY work, white would generally only be carried by the sheds, wholesalers would always have grey, I understand it was different down south?

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Bathroom Junction Box

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